The economic landscape has been visibly altered in the past few weeks by the abrupt jolt in interest rates that has tilted the terrain toward savers and lenders, leaving surprised borrowers and wary investors scrambling on a slippery, even if stable, slope.

The housing market was the first to feel the impact as the sudden 2-percentage-point jump in most mortgage rates that slowed home sales and stunned buyers who had taken out variable rate mortgages. Homeowners who decided to borrow against their equity also are facing higher rates, and they will not be protected by the rate caps that limit increases in variable mortgage payments.

The other side of the interest rate equation is paying off for those with money to save or invest. They are shifting their cash into money market funds, certificates of deposits and interest-paying investments whose yields continue to rise. Washington-area banks and savings associations today are offering as much as 9 percent on some accounts. Most deposit rates remain in the 7 or 8 percent range, because the full impact of the move in bond rates has not been filtered through to savings accounts.

Nationwide more than $5 billion in new money has poured into money market funds in the past three months, reversing what had been a steady flow of money fund assets into the booming stock market. Though the Dow Jones industrial average continues to climb, mutual fund investors pulled $11 billion out of their accounts in April, the latest month for which details are available.

Whether Americans will -- or should -- continue to shift their money from stocks to interest-paying investments remains the cloudiest aspect of the interest impact forecast. The strength of the stock market makes clear there has yet to be an exodus from equities. Paradoxically, if stocks continue to climb, more and more investors may decide not to be greedy and get out before the inevitable topping out. And if stocks start to fall, it may be hard to resist interest rates that have again approached double digits.

There are other paradoxes resulting from the jump in rates and nowhere will they be more obvious than in new car showrooms, where interest rates are nearly as critical as they are in housing. It will cost car makers millions of dollars more to subsidize the cut-rate loans they have been using to sell cars, yet they will have no choice but to continue them or some even more costly sales incentives. Rather than pushing up monthly car payments, higher interest rates may hold them down. Would-Be Buyers, Sellers Wary

Jerry and Nancy Megas had been hoping to sell their Arlington house and buy a larger one, but that was before mortgage rates took off. Now they're in a squeeze.

"On one side, fewer people can afford our house. . . and on the other, we can afford less of a move-up house than we originally expected," Jerry Megas said.

The Megases have plenty of company in their predicament, as other potential move-up buyers have found themselves scaling back their expectations or canceling their plans. Other early casualties of the rate increases are owners who hoped to refinance their mortgages and buyers who cannot afford the higher monthly payments.

"We had a buyer who, because of the rise in rates, couldn't qualify for a loan," Megas said. In their search for a house to buy, the couple also has discovered that some sellers will not accept contracts contingent on the sale of their home. "They probably think that with rates going up it may be difficult for us to sell our house," he said.

At the same time, refinancings, which had been booming when rates were low, "have just about ground to a halt," according to Warren Lasko, executive vice president of the Mortgage Bankers Association of America.

Mortgage interest rates stunned buyers, sellers and the real estate industry by soaring 2 percentage points in the past two months. At the end of March, most lenders in this area were offering 30-year fixed rate loans at 8 1/2 and 9 percent, plus 1 1/2 to 4 points, and adjustable rate mortgages at 7 and 7 1/2 percent plus 1 1/4 to 3 points. Last week the fixed rate loans were 10 1/2 and 11 percent, with about the same points, and ARMs were at 7 1/2 and 8 1/4 percent, with 2 to 4 points. A point equals 1 percent of the loan amount.

Lenders are still processing applications received before rates shot up, but some borrowers may not get the interest rates they expected. Frank T. Davis, an assistant to the assistant comptroller general in the General Accounting Office, has been told by his lender that the 8.75 percent rate he was promised in March for refinancing his Adelphi home will rise, probably to more than 10 percent, because the paper work will not be completed before his commitment expires.

Homeowners with adjustable rate mortgages and home equity loans will face another kind of rate squeeze, as monthly payments on both go up. Nearly all adjustable mortgages have a limit on rate increases, but home equity loans generally do not.

Sales of homes began declining as interest rates started rising, although in some areas purchasers are still rushing to buy before rates go even higher, according to developers and real estate agents. Fewer homes are available for resale, in part because many owners who intended to sell have decided to wait, they said.

"This time of year, the market should be booming" but it is not, said Kathy Eaton, a sales agent in the Vienna office of Shannon & Luchs.

"People have less buying power when rates go up, so typically prices go down when rates are up," said William A. London, a mortgage banker in McLean. For example, a buyer who could afford a $250,000 house when interest rates are at 9 percent would have to drop to a $200,000 home if rates went to 11 percent, he said.

Jan and Ray Tarasovic, who recently sold their Burke Center town house and have found a house they hope to buy, are watching the interest rate movements nervously. If the rate "climbs another point" before the couple can get a loan approved "we may have to reconsider," Jan Tarasovic said. "I think we're going to be okay but we're not happy."

Fewer prospective buyers are looking for newly built homes now, several builders said. The number of shoppers visiting Ryland Group Inc. homes is off 20 percent from a year ago, said company President C.E. Peck. Ryland sales in Maryland, Virginia New Jersey and Pennsylvania declined by 33 percent in the first quarter of 1987 from the same period last year, he said.

Even a small interest rate increase can make a big difference in whether many young buyers looking for their first homes will be able to buy. As rates have risen, "first-time buyers have gotten frightened and many have dropped out of the market," said Audrey Bragg, of Long & Foster Realtors' Hyattsville office. Bragg said, however, that home sales are still brisk in the Hyattsville area, where home prices are lower than in many other parts of the Washington area. -- Ann Mariano Auto Incentives Intact

Consumers are in the driver's seat, especially if interest rates continue to rise.

For auto makers and dealers, it is a different story, because they are looking at the buyers' market from the other side. To work that market, auto companies have had to offer rebates and cut-rate financing.

Bigger interest rates widen the disparity between the prices at which the companies borrow money and those at which they lend it to consumers, thus increasing the cost of sales incentive programs.

"High interest rates are bad for this business. There is a psychological component to auto buying. High interest rates make consumers nervous," said Maryann N. Keller, chief industry analyst at Furman Selz Majer Dietz and Birney Inc. in New York. "If you have higher interest rates, you'll also have an overall reduction in new car sales," she said.

In a market where new car sales are at a seasonally adjusted rate 19.5 percent below last year -- with sales incentives in place -- auto companies can ill afford to do away with their lures, no matter the cost.

If enough customers stay away, car manufacturers and dealers could feel pressed to offer even bigger incentives or to take the drastic step of cutting sticker prices to try to boost sales.

If new car finance rates rise significantly, "car companies are going to have a whole lot more to worry about than the costs of their sales incentive programs," Keller said.

For the moment, auto makers and their dealers say they are not worried. "Interest rates on new car loans are still competitive," said Lou Kairys, president of Lustine Chevrolet in Hyattsville.

"You've got to remember that, say, three or four years ago, a large segment of people saw interest rates climb as high as 18 percent" on new car sales transactions, Kairys said. "By comparison, today's rates look good."

In March, banks were charging an average 10.4 percent annually for new car loans, compared with an average 10.8 percent charged by captive finance companies such as General Motors Acceptance Corp., the finance arm of General Motors Corp.

Those figures from the Federal Reserve Board might surprise people who believed the average captive finance rates were lower because nearly all of the captive companies have offered cut-rate financing on new car loans.

But inexpensive financing often requires higher monthly payments over shorter loan periods. Despite all of the hoopla over cut-rate financing, most car buyers choose longer-term, higher-rate loans that have lower monthly payments.

The key to keeping those and other buyers in the market is lower overall car prices, Kairys said.

"There's really no difference between what happens when sticker prices increase and interest rates increase," Kairys said. "With each increase, bit by bit, a segment of the new car market is eliminated.

"One day, you look around and realize that: 'Hey, here I have 100 customers who could have bought a car seven months ago, but they can't buy one today.' "

"We haven't reached that point, yet," said Joe Herson, president of Manhattan Auto in Rockville. "At the moment, the rise in interest rates is small. And with so many financing deals out there, that small rise is not a tremendous issue as far as buyers are concerned," said Herson, whose dealership sells low-cost Hyundai and Subaru cars and expensive Audi, BMW, Jaguar and Porsche models.

But Herson tempers his optimism with caution. "Rising interest rates are bad news," he said. "And no economic news that can be interpreted as negative is good for the car business," he said. -- Warren Brown A Cautious Look at Stocks

"Money flows to where it can get the best return for the least risk," said John Connolly, head of investment policy at Dean Witter Reynolds Inc. "The risk has risen in the stock market, while the returns have risen in the bond market."

The result is a renewed debate among investors over whether stocks, bonds or bank certificates are the wisest investments. As Connolly put it, "You've got people searching for answers. And it's not clear what the answers are."

When interest rates jumped and bond prices fell dramatically in April competition unexpectedly returned to the stock market, which until then had offered the best deals.

With yields on bellwether 30-year Treasury bonds moving from around 7.5 percent to the 9 percent range, bonds have become increasingly competitive with stocks, Connolly said. Some high-grade corporate bonds yield about 2 percentage points above Treasuries. Stocks, meanwhile, offer a total return of 8.5 percent to 9.5 percent including dividends and estimated appreciation, Connolly said. Bank certificates of deposit offer 6.5 percent for six months with almost no risk.

Investors who believe in stocks say corporate profits are rising so rapidly that the equity issues will provide an unusual amount of capital gains this year.

Connolly said his firm has become more cautious. An average investment fund, he said, is made up of 58 percent stocks, 35 percent bonds and 7 percent cash. But Dean Witter's current allocation is: stocks 50 percent, bonds 33 percent and cash 17 percent.

Connolly said that despite daily ups and downs in the bond market, "These rates will be around for a while." He foresees interest rates remaining at current levels for the next couple of months and then moving higher in the second half of the year. In time, he said, the higher rates would affect other markets, particularly real estate. "I think we're going to see reduced availability of funds and a higher cost of funds. It's going to hinder the economy."

Connolly said the stock and bond markets were undergoing intense scrutiny from institutional investors, especially corporate treasurers and portfolio managers who manage multimillion-dollar pension funds. An all-out flight from stocks to bonds, Connolly said, hasn't happened yet, but investors are continually weighing their options.

Even before interest rates began to move upward, investors began moving away from consumer stocks that benefit from lower inflation and toward durable goods that benefit from higher inflation, according to Charles Comer, market analyst at Moseley Securities Inc.

The shift began last summer when oil prices moved higher. It continued in late December and picked up steam in February when interest rates seemed about to bottom, Comer said. Comer said his firm is leaning toward stocks because of the ability of selected stocks to outperform bonds on a longer-term basis.

Comer said he expects corporate profits to improve substantially because of a heavy emphasis on cost-cutting and improving productivity. As a result, he said, stocks still hold a potential for capital gains that are persuading some investors to keep their money in stocks. -- Stan Hinden Credit Cards Still Costly

For consumers, there is good news: Credit card and many other consumer loan rates so far haven't risen along with most other interest rates in recent weeks.

And there is bad news: The reason these rates haven't jumped is that they never came down out of the double digits in the first place.

Interest rates on unpaid credit card balances had been declining slowly in the past year because of competition and the threat of federal legislation, but the national average rate last month was still 17.29 percent. Some banks were charging as little as 10.5 percent in April, according to the Bank Credit Card Observer, but almost all of the lowest rates are variable ones pegged to such national indices as the prime rate, the discount rate or the rate on six-month Treasury bills. Holders of these cards should begin to see increased rates soon.

There are no legal limits to the amount rates can rise, so nervous cardholders whose banks charge variable rates may want to switch to a fixed rate card if they do not pay off bills immediately, said Observer publisher John C. Pollock.

Credit card charges, however, generally involve relatively small amounts of money when compared with home equity loans, a form of second mortgage that more and more homeowners are using to finance everything from college tuitions to trips to the Caribbean.

Home equity loans are heavily advertised and offer temptingly low rates. Some are still being offered here and elsewhere at very low promotional rates. Riggs National Bank, for example, is still advertising a loan for 5.9 percent for six months. After that, the rate changes to 1.5 points over prime, or 9.75 percent currently. Most equity lenders surveyed by Bank Credit Card Observer also have variable rates pegged to the prime and are in the same 9 percent to 10 percent range as Riggs, or three quarters of a point higher than they were before rates rose.

But unlike variable rate first mortgage loans, which usually cannot rise more than 2 percentage points in a year or 5 points over the life of the loan, variable home equity loans carry no such limits. Moreover, some permit interest-only payments. Consequently, a sharp rise in interest rates is likely to strap some borrowers and could cause lenders to foreclose on homes.

Stephen Brobeck, executive director of the Consumer Federation of America, recommends that some people may want to switch to fixed rate home equity loans. However, that may entail refinancing charges, as well as a greater total finance charge if the terms are lengthened.

Thomas Honey, president of the Consumer Bankers Association, calls such talk exaggerated. "Most Americans know when they have reached their debt limit; there is little danger they will endanger their homes by using home equity loans to fund current expenses." In fact, he noted, many people make three times the minimum required monthly payment of 1.25 percent to 1.75 percent of outstanding balance.

He observed that a 1 percent rise in interest rates on a $10,000 loan means the minimum monthly payment increases by just $8. Those borrowers who pay interest only or have a fixed term loan will experience an increase, but those with an open-end loan will make the same payment, composed of more interest and less principal. -- Nancy L. Ross Pressure on Developers

Fearing a further increase in interest rates, many commercial developers are racing to lock in rates on construction loans and some are beginning to think twice about moving ahead with their next project.

At the same time, developers said the increase is hardly as bad as it could be. "It's a warning sign for everybody," said Ron Walton, president of Walton Corp., which is developing Dominion Point, an 80,000-square-foot office project on Rte. 7 in Loudoun County. "It's making everybody look at their budgets real carefully."

Many developers said they are going to continue with their existing projects and those planned for within the next year. But the rising interest rates mean that those who did not lock in their rates in the past three months are going to pay more for their loans. That's why several developers are moving more quickly to get their lenders to give them a fixed rate and get the application approved before rates go higher.

"Everybody is scurrying to buy permanent loans so they get the fixed rates," said Ray Smith, president of Webb-Sequoia, a firm that does commercial and residential building in the Washington area. "We weren't in as great a hurry . . . three months ago."

Walton said he figures a 1 point rise in interest rates -- from 9 percent to 10 percent -- on a $14.5 million construction loan for a 125,000-square-foot office building costs a developer an additional $350,000.

Developers of speculative office buildings are most vulnerable to the rate increase because it boosts the costs of holding the building while waiting for space to be leased out. At the same time, lenders, who consider many of these kinds of office projects very risky, are a bit more hesitant about advancing money for such development.

"Developers are going to have to sharpen their pencils in terms of speculative office space because the cost of money is higher," said Stephen Goldstein, a senior vice president with Julien J. Studley Inc., a real estate brokerage and development firm.

Any cost increase threatens the viability of such projects because most markets already have an oversupply of space, leaving developers little room to raise rents.

According to Cushman & Wakefield, a national commercial brokerage, the national average office vacancy rate was 13.5 percent in the first quarter of 1987, down from 14.4 percent in the previous quarter. In Washington, the average vacancy rate is 10.3 percent, which is considerably lower than the rate of 29.6 percent in Austin, Tex., the highest in the country.

Justin Hinders, a longtime Washington real estate investor, broker and consultant, said the rise in rates already is affecting the cost of development and investment property.

"If you have to pay 1 point or 1 1/2 point more in interest, it is certainly going to have to affect the cash flow of the project," Hinders said.

John Fagelson, a Washington attorney who represents commercial developers, said his clients are trying to structure contracts so that they take into account the possibility of a rise in interest rates and the subsequent increase in the cost of maintaining the building. Within the past month, he has had only one developer walk away from a contract because of rising interest rates.

Victor Trapasso, president of GT Realty & Management Co., which is developing a 2-million-square-foot office complex near Washington Dulles International Airport, said, "The atmosphere right now is cautious and conservative. . . .People are sitting back, looking at the market and making sure they have a good, solid project before they go ahead with it." -- Cornelius F. Foote Jr. Corporations Pulling Back

Officials at ERC International Inc., the Fairfax-based professional services firm, were in the midst of a "road show" for a planned debt offering earlier this month when they realized they were in trouble.

It was the week of May 11, and the officials were on the road touting the offering to analysts and potential investors in cities around the country. But as they were making their pitch, interest rates were moving up, reducing the attractiveness of the $25 million package.

When ERC began working on the offering earlier this year, interest rates were in the 6 percent to 6 1/4 percent range, giving the company a nice advantage over borrowing money at the prime rate, then 7 1/2 percent. By mid-May, however, bond rates had climbed as high as 7 3/4 percent while the prime had gone to 8 1/4 percent, reducing the edge.

"The bond market just caught up very quickly with the prime, and the window just closed," said Joseph Procopio, a spokesman for ERC. "By the 15th of May, we could see that the market had deteriorated significantly." As a result, the company decided that it didn't need the $25 million desperately and, on May 18, it suspended the offering indefinitely.

ERC is one of a number of companies whose plans to go to market for new money have been thwarted by rising rates. Although rates have not risen nearly enough to dry up corporate financing completely, experts say that some deals are being suspended and others revised to reflect the changing market conditions.

The rising rates also are putting some pressure on debt-heavy companies whose interest payments float with the market. Many companies took advantage of months of low, stable interest rates to refinance at fixed rates or to purchase interest rate insurance. But others, such as some companies that have been through -- or which are going through -- leveraged buyouts, have felt the squeeze of the recent point-plus increase in interest rates.

"It affects all the outstanding deals that have floating-rate debt outstanding. That's a one-way street," said the director of leveraged buyouts for a large Wall Street firm. "With the prime {rate} going up three-quarters of a point, everybody's costs have gone up commensurately." He noted that the recent three-quarter-point rise in the prime to 8 1/4 percent from 7 1/2 represented a potential 10 percent increase in interest costs.

However, he said, so far the problems have not been severe. "I haven't seen anything terribly dramatic happen as a result of the interest rate run-up," he said.

Many experts have warned that a sharp increase in interest rates could scuttle some companies that are heavily in debt because of leveraged buyouts, but they say the recent jump has not been sufficient to do that. "I think there's a fair amount of exposure out there," the Wall Street executive said. "If the rates were to run up sharply, there would be some sharp pain among some of the deals that have been done in the past few years."

What the recent increase has done, experts say, has been to make it harder to put together chancier leveraged buyout deals. "It sure can take the fun out of a marginal deal," one said.

The interest rate increase also has helped dry up the market for new stock offerings, which was booming just a few months ago. Many companies, seeing that strength, began preparing public offerings, only to find the market struggling by the time they were ready to sell the stock this month.

"With the interest rates jumping up in the last month, clearly the interest in equities has slowed just a bit," said Richard Franyo, managing partner and head of the investment banking division at Alex Brown & Sons, the Baltimore brokerage. Higher interest rates can sour stock offerings because they may move investors to invest in bonds rather than in stock, and they can increase a company's cost of doing business, thus reducing earnings.

"The most direct impact of the higher interest rates has been on the financial intermediaries. The interest in bank and thrift stocks is very soft," said Franyo, because it is difficult for those institutions to fully pass the costs of higher interest rates on to their customers.

On the other hand, he said, many offerings in other sectors, such as technology, have seemed to be unaffected by the increase in interest rates. "Some offers are hotter than ever, and others couldn't be colder," he said.

Procopio said ERC's investment bankers had simple advice for the company on how to deal with the impact of higher interest rates on planned corporate finance offerings. "If you don't have to, the advice is, don't do it," Procopio said. -- Mark Potts Banks, S&Ls May Suffer

Higher interest rates will put savings and loans and banks to the acid test, revealing which ones had the foresight to replace fixed rate loans in their portfolios with variable rate ones as a protection against a rise in the cost of money.

Banks and S&Ls that have stuck mostly to selling fixed rate loans are likely to suffer the most. "It all has to do with the memory of the executive," said Alex Sheshunoff, president of Sheshunoff & Co., a bank consulting firm in Austin. "Those with longer memories who recall the late '70s and early '80s sold fixed rate loans. Those with shorter memories kept them."

"The best companies have done the best job of insulating themselves," said Jonathan E. Gray, S&L analyst for Sanford C. Bernstein & Co., an investment banking firm in New York. "There are many others who have been just barely hanging on where earnings may just evaporate."

The increased pressure on ailing institutions comes as the banking and S&L industries are reeling from falling oil and real estate prices and from defaults on foreign loans.

The S&L industry is likely to feel the impact of changing rates more than the banking industry, which in general is viewed as healthier and less tied to long-term loans such as home mortgages. But in economically depressed regions such as the Southwest and Midwest, S&Ls and banks are likely to suffer equally as rising rates put even more pressure on borrowers already having trouble meeting payments.

"Obviously the sicker institutions will get sicker," said Robert Sahadi, director of policy and research at the Federal Home Loan Bank Board, the federal agency that regulates S&Ls.

But he said he is encouraged by how many S&Ls have restructured their balance sheets by focusing on variable rate mortgages. He said that five years ago S&Ls held few variable rate instruments while today 45 percent of the home mortgages they hold are variable rate loans.

P. Michael Laub, director of economic and policy research for the American Bankers Association, the industry's largest trade group, said banks have relied more and more on consumer loans to make up for dwindling demand from commercial borrowers. He said higher rates may slow consumer demand for loans and intensify competition for high quality borrowers.

The banking industry's earnings declined last year for the first time in 25 years, with one of every five banks losing money. Despite the decline, the industry as a whole still made a profit. During the same period, one in every five S&Ls lost money, but the losses more than offset the gains of those that made a profit, according to analyst Gray. The S&L industry as a whole lost an estimated $700 million. -- Kathleen Day Delayed Effects for Some

Rising interest rates could increase the payments that struggling Latin American countries must make on their foreign bank debt, but the effect will take a while to materialize -- assuming rates keep going up -- and could be muted by other economic changes.

Interest on nearly all of the roughly $300 billion that Latin American nations owe to commercial creditors fluctuates with market interest rates. (Interest on loans made by international lending agencies and governments -- about $80 billion to Latin America -- is usually at a fixed rate.)

For every one-percentage-point increase in rates, payments on the private debt rise by $3 billion a year. For Brazil, the largest Third World debtor, that would translate into about $800 million in higher payments each year. Mexico, the second-largest debtor, would pay $770 million more.

However, higher interest rates will not raise payments of debtor countries for at least several months. The loans are pegged to the benchmark London interbank offered rate (Libor), which has gone up about 1.5 percentage points from its low of 6 percent. Libor fluctuates every day, but rates on most of the loans to debtor nations adjust only every six months (a few adjust every three months).

The first payment on a hypothetical loan granted on March 31, for example, would fall due on Sept. 30, and the interest owed on it is based on what Libor was in March. The next payment, due the following March, will reflect the interest rate prevailing in September. Each debtor country has an array of loans with different due dates, making it difficult to predict when the country would first face higher rates -- especially since it is not clear whether interest rates will rise further.

"It's certainly manageable," said Deputy Assistant Treasury Secretary James W. Conrow. "The forecasts we have seen don't pose major problems."

Meanwhile, other economic indicators indirectly related to higher interest rates could help mitigate the impact of higher debt service payments. Faster economic growth -- a possible cause for rising rates -- also could serve to raise commodity prices, an important source of export earnings for many debtor nations. So could fears of increased inflation.

Prices of such export commodities as silver, tin, copper and agricultural goods already have climbed an average of 10 percent in recent months. Oil prices have stabilized, although coffee prices remain very low. Faster economic growth also could stimulate demand for Latin American exports.

"Overall, the impact of interest rate increases may in fact be very little" as a result of other economic factors, said Pedro Pablo Kuczynski, co-chairman of First Boston International, an investment bank.

Nor have the increases in Libor been very large so far, especially in comparison to the amount by which the benchmark rate fell last year. The three-month Libor rate, for instance, averaged 7.91 percent in the first quarter of 1986 but was only 6.38 in the first quarter of 1987.

Libor "still averaged less in the first half of this year than it was in the first half of last year. Since there is a lag, no matter what happens for the rest of the year we won't feel much of an effect," said Jack Guenther, senior adviser for international operations at Citibank.

For some countries, an increase in interest rates would have no effect on their debt service payments -- because they aren't paying. Brazil, Ecuador, Costa Rica, Bolivia and Peru are among the countries that have suspended payments on their debt.