The effect of aging on beta-adrenoceptor-stimulated cyclic AMP formation in human lymphocytes.

1. Responsiveness of the beta-adrenoceptor adenylate cyclase system was measured in lymphocytes from healthy young and old subjects by incubating the cells with isoprenaline in the presence of a phosphodiesterase inhibitor and by measuring production of adenosine 3':5'-cyclic monophosphate (cyclic AMP) with a competitive binding assay. 2. The two groups did not differ significantly in the levels of cyclic AMP produced or in the concentration of isoprenaline required to give half-maximal stimulation of the cells (ED50).