Age-related alteration in adrenoceptor and its physiological responses.

点击翻译按钮获取中文摘要

We investigated the relationship between the adrenoceptor signal transduction and the membrane composition in rat cerebral cortex, parotid gland and ventricular myocardium during aging. 1. Cerebral cortex: The density of specific [^3H]prazosin binding site reduced with advanced age, but the binding affinity for [^3H]prazosin did not. Norepinephrine (NE)-induced formation of [^3H]inositol phosphates increased with advanced age. The cholesterol content in membranes increased with advanced age; concomitantly, an increase of the ratio cholesterol/phspholipid was observed. The membrane viscosity as measured by using 1,6-diphenyl-1,3,5-hexatriene increased with advanced age.2. Parotid gland: NE-induced of K^+ release from the slices reduced with advanced age. The density of specific [^3H]prazosin bindng site increased with advanced age, but the binding affinity for [^3H]prazosin did not. NE-induced formation of [^3H]inositol phosphates decreased with advanced age. No difference in isoprotere … More nol (ISO)-induced decrease in K^+ release and increase in cyclic AMP content were observed at any age examined. But the binding affinity for [^3H]dihydroalprenolol binding site reduced with advanced age, and the binding affinity for [^3H]dihydroalprenolol increased. The cholesterol content in membranes decreased with advanced age; concomitantly, a decrease of the ratio cholesterol/phospholipid was observed. The membrane viscosity decreased with advanced age.3. Ventricular myocardium: The density of specific [^3H]prazosin binding site reduced with adanced age, and the binding affinity for [^3H]prazosin increased. NE-induced formation of [^3H]inositol phosphates decreased with advanced age. The cholsterol content decreased with advanced age; concomitantly, a decrease in the ratio cholesterol/phospholipid was observed. The membrane viscosity decreased with advanced age.These results suggest that the both altered cholesterol/phospholipid ratio and/or membrane viscosity during aging may account for the changes in adrenoceptor signal transduction. Less