ADRENOCEPTOR COUPLING MECHANISMS WHICH REGULATE SALIVARY SECRETION DURING AGING

In parotid slices and membranes from Wistar rats 2, 12 and 24 months o ld, changes are noted in adrenoceptor-stimulated K+ fluxes, formation of [H-3]inositol phosphates ([H-3]IPs), cAMP production, and membrane environment. Norepinephrine-stimulated K+ efflux and formation of [H-3 ]IPs in the slices proceed through an alpha1-adrenergic mechanism and are reduced 20% and 40% during aging, respectively. In beta-adrenocept or stimulation with isoproterenol, no age changes were observed in Kinflux and cAMP production. The cholesterol content in membranes was r educed with age; concomitantly, the membrane viscosity decreased with age. These results indicate that the alterations in the membrane envir onment may provide age-dependent modulation of alpha1-adrenoceptor cou pling mechanisms and their functions.