Michael Kirschenbaum, 52, a professor of medicine and chief of nephrology at the Veterans Administration Hospital in Long Beach who was active with the National Kidney Foundation. Born in New York, Kirschenbaum studied the basic mechanisms of kidney functions and helped trained numerous clinicians and scientists interested in kidney research. He received his bachelor’s degree from the City University of New York and his medical degree from the State University of New York. After completing fellowships on kidney research at Ohio State and the University of Texas Health Science Center at San Antonio, Kirschenbaum was on the faculty at UCLA for 10 years. He later joined the UC Irvine program at the VA Hospital in Long Beach. He received several awards, including a Senior Investigatorshipof the American Heart Assn. in 1976. On June 21 in Santa Monica after a long illness.