U.S. senators are important people, accustomed to public toasts, but few could compare with the little surprise the University of Washington gave Warren G. Magnuson.

During a big football weekend in 1977, the marching band spelled out "Maggie" on the field to honor a man who once played football for the Huskies.

But a more significant tribute came that weekend. The university's Health Sciences Center, six schools housed in a 2.4-million-square-foot building, was renamed for the Democratic senator.

Over a period of 30 years, a good deal of federal money had helped build the center. It was due in large part to the influence Magnuson had collected since 1937 in Congress, where he is called "Mr. Health."

Dr. Jack Lein, from the school of medicine, was talking about that federal connection when he hit the punch line.

Looking over at Sen. Magnuson, he quipped: "If you don't keep it coming, Maggie, this will become the world's largest Christain Science reading room."

Even Magnuson had to laugh, but Jack Lein was putting his finger on one of the verities of life in the world of medicine and biomedical research.

Without the vast infusion of federal money, medical research of the kind that developed the frist artificial kidney 20 years ago at Lein's university wouldn't get very far. Magnuson is a key figure in the money-to-research transfer.

The bulk of the nation's biomedical research is paid for, channeled through and conducted by the National Institutes of Health for which President Carter is seeking $3.6 billion in his fiscal 1981 budget.

There will be much debate in Congress over the amount and its intended uses, but it will be guided and decided in the main by Magnuson and a handful of other legislators who are the fiscal overlords of NIH.

Overlords is not an excessive word. Congress controls the federal pursestrings and it is in the appropriating committees that the string-pulling power lies. Legislators battle for vacant seats.

The central forum for the debate over NIH will be the Labor-HEW subcommittees, which have begun annual hearings on the president's proposals. Decisions they make during coming months will determine in large degree what NIH does and spends in fiscal 1981.

Between them, the House and Senate subcommittees have 26 members. While representing a range of politica philosphies, they tend to be generous and sympathetic toward NIH. Year after year, Congress has given NIH more than presidents have requested.

This happens for many reasons. Magnuson likes to call NIH the first link in a long chain of disease prevention. Put the money in basic research and the dividends will be handsome, the argument goes.

But there are other influences. New institutes and programs have come into existence at NIH because health associations lobbied Congress to push NIH into diseases they were fighting. Other times, constituents pressured for more research and more cures. Legislators or their families suffering from specific ailments provided impetus.

A light was shed on this last year by Rep. Robert H. Michel (R-III.), the ranking Republican on the House subcommittee, who usually advocates budget cuts for NIH.

Michel showed a new interest in the National Cancer Institute's (NCI) work on screening for cancer of the cervix. He told a dramatic, touching story of his wife suffering from concern over a tumor that turned out to be benign. Research and screening took on new meaning.

But other lesislators have become outspoken champions of certain research programs -- and in a position to make a difference through their subcommittee positions.

Sen. Birch Bayh (D-Ind.) long has pushed for intensified cancer research, last year urging Magnuson to allow NCI's budget to reach $1 billion -- which it did. Bayh's wife, Marvella, died of cancer. In 1976, he underwent surgery for removal of a spot on his lung that was diagnosed as non-cancerous.

Sen. Richard S. Schweiker (R-Pa.) is a textbook example of appropriations activism. For several years he has pushed the subcommittee toward more spending on hearing research. Schweiker suffers from hearing impairment, as do about 15 million other Americans.

But Schweiker is better known as the No. 1 congressional enemy of diabetes. That happened because some constituents in the early 1970s complained to him that NIH was not devoting adequate attention to diabetics' problems.

Schweiker investigated and decided to act. As the ranking Republican on both the NIH authorizing and appropriating subcommittees, he has double clout. His authorizing bill led to a national study of diabetes, which determined the problem was huge. He then pushed an increase in diabetes research spending through the Senate.

In 1974, before Schweiker was successful, NIH was spending about $20 million on diabetes research. By 1976, it was up to $40 million and today it is about $135 million -- with major treatment breakthroughs on the horizon.

Other subcommittee members have taken similar interests in other fields (leading to "disease-of-the-month club" jokes) but Magnuson is the man to watch on the Senate side.

He is chairman of the full Appropriations Committee, as well as the Labor-HEW subcommittee, and basically what he says goes. Last year, apparently sensing budget-tightening winds in his own 1980 reelection campaign, he stressed holding the line. For the first time in history, the House came up with a larger NIH appropriation than the Senate.

Most people in Washington's large health lobby saw that as a curious aberration, because Magnuson's counterpart on the House subcommittee is Rep. Willima H. Natcher (D-Ky.), a fiscal conservative known as "a tough nut."

Natcher is a "tough nut." A measure of the seriousness with which he takes his job is that he has never missed a House rollcall since coming here in 1954. He is a skilled parliamentarian who runs courteous but tight hearings.

The thinking on his subcommittee runs from the bright progressive represented by Reps. David R. Obey (D-Wis.) and Silvio O. Conte (R-Mass.), both students of NIH procedures, to the urban liberalism of Louis Stokes (D-Ohio) and the conservatism of Michel and George M. O'Brien (R-Ill.).

Natcher last year was in his first term, working his way cautiously through the complex NIH budget. When it came time to "mark up" a bill -- that is, draft a final version -- Natcher moved to exclude the public.

That move, ostensibly to reduce lobbyists' access, worked. But it infuriated many of the public health associations that had pressed for years to have subcommitte sessions opened at all times.

While Natcher had enough votes to close the meeting, he did not have enough votes to hold off a series of amendments that beefed up NIH spending. The result was a more costly measure than the Senate's.

With that memory, the health groups are going up to Capitol Hill this year with eyebrows arched in doubt. No one is certain how Congress will treat NIH this time around.