For the men and women in state government, President Reagan's plan to shift responsibilities from Washington to the 50 states is both exhilarating and unnerving. You could see both reactions during the meetings here last week of the National Conference of State Legislatures (NCSL).

It was not very long ago that the typical state legislature was a collection of part-time, amateurish politicians, meeting for 60 days every other year, with little staff or information resources of their own, ratifying the governor's budget and passing whatever bills were uppermost on the lobbyists' minds.

Some legislatures still fit that description. But the vast majority of the 2,500 legaslators who met here come from different kinds of bodies, where committees work year-round and legislative staffs monitor programs and spending in the executive branch. They spent their days at sessions on topics like "Juvenile Justice in the States" and "The Legislative Role in Budget Cutback Management."

Their emergence has been recent; NCSL as an organization is only eight years old. And the thoughtful legislators are aware that, institutionally, the legislatures are like gangling teen-agers, who are suddenly being told that Big Daddy in Washington is moving away and they're going to have to manage the household on their own.

There is clearly a lot of talent and energy among these folks. But there are also some real problems, which tend to get overlooked in the abstract Washington debates about "sorting out" responsibilities between federal and state governments.

There is, for example, the fact of a hellishly high turnover rate among state legislators--and it's apparently going up, just at the time when all these new responsibilities are cascading down onto the states. Alan Rosenthal, the director of the Eagleton Institute at Rutgers University, probably the country's leading center of study of legislatures, told a panel here that the turnover rate, which has been running about 20-25 percent per session, is likely to jump above 40 percent this year.

Some of that is the result of redistricting and reapportionment. Some of it is a jump in voluntary retirements, with many individuals finding the pressures and time demands of the job interfering with private careers and family lives. And some of it is the increased competitiveness and cost of legislative elections.

The result, Rosenthal said, is "the loss of institutional memory at a time when public policy cries out for continuity and judgment."

An example is provided by Roger D. Moe, the majority leader of the Minnesota state senate. Minnesota legislators have endured two regular and four special sessions on the budget crisis in the last 18 months. So many of them are quitting that Moe says there will be at least 10 new senate committee and major subcommittee chairmen in January. He is one of only five people in the 67-member senate with as much as a decade's experience.

The shorter the tenure of elected officials, the greater the power of the permanent government in the state capitols--particularly the lobbyists. They were very visible here.

Most legislatures have ended the old practice of lobbyists signing tabs for all the food, drink and entertainment the legislators could consume away from home. But the lobbyists were swarming here.

One evening, associations of bankers, realtors, retail merchants, manufacturers and hospitals, plus the National Can Corporation--all with obvious interests in state regulatory and tax policy--played host at lavish receptions atop five Chicago skyscrapers. By one rough estimate, there were at least 50 hospitality suites in the convention hotels, each with an interest-group sponsor.

More than 80 major corporations and trade associations, ranging from the Aluminum Company of America to the U.S. Brewers Association, belong to the State Government Affairs Council (SGAC), an organization of lobbyists which meets at the same time and place the NCSL gathers each year and conducts joint projects with NCSL.

The costs of two of NCSL's convention plenary sessions last week--a panel on the economy and a panel on biotechnology--were underwritten by SGAC. Since 1981, SGAC and NCSL have also run annual joint training sessions for key legislative staff members and annual issues seminars for legislatave leaders, with corporate funds subsidizing and corporate personnel helping staff the sessions.

Kansas senate president Ross Doyen, the outgoing president of NCSL, said, "I don't have any concern about these people (the lobbyists) participating" as they do in underwriting and staffing the sessions. "I think it's an excellent thing they've taken this interest."

But, as Reagan's policies continue to shift power to the states, other groups will follow the corporations in "taking an interest" in how the legislatures are really functioning.

At that point, the tenure, the experience, the judgment--and, yes, the independence--of the legislators had best be ready to stand scrutiny.