The death of a 23-year-old nursing student while participating in a National Institutes of Health study has prompted the federal research center to tighten restrictions on the use of volunteers in more than 600 federally funded research facilities.

NIH officials said that, "wherever possible," volunteers will be asked to supply written documents detailing their medical history and to submit to thorough physical examinations throughout the research.

The new guidelines are the latest repercussion from the death Saturday of Bernadette Gillcrist, 23, of Bethesda.

On Wednesday the Food and Drug Administration said it would investigate the circumstances surrounding her death, which occurred while she was participating in research to test the effects of lithium, an antidepressant, combined with AMPT (alphamethylparatyrosine), an experimental drug. The sleep labroatory conducting the test has been shut down.

The cause of her death has not yet been determined, although hospital officials now believe it resulted from a past heart ailment Gillcrist concealed from the study's director.

In a letter to 600 national research facilities that received NIH funds Dr. Charles McCarthy, director of NIH's office for protection from research risks, warned researchers to monitor any similar studies carefully.

The drug AMPT, which the Food and Drug Administration said is being used by only six physicians in the country, "will probably be subjected to further testing in animals," McCarthy said yesterday.