Age-related alteration in adrenoceptor and its physiological responses.

研究衰老大鼠大脑皮层、腮腺和心室心肌中肾上腺素能受体信号转导与细胞膜组成的关系。1. 大脑皮层：随着年龄的增长，[^3H]prazosin特异性结合位点的密度降低，但对[^3H]prazosin的结合亲和力不变。去甲肾上腺素（NE）诱导的[^3H]肌醇磷酸的形成随着年龄的增长而增加。膜内胆固醇含量随年龄增长而增加；同时，胆固醇/磷脂比值升高。用1,6-二苯基-1,3,5-己三烯测定的膜粘度随年龄的增长而增加。腮腺：ne诱导的K^+释放随年龄增长而减少。[^3H]prazosin特异性结合位点的密度随着年龄的增长而增加，但对[^3H]prazosin的结合亲和力没有增加。ne诱导的[^3H]肌醇磷酸的形成随着年龄的增长而减少。在任何年龄，均观察到更多的nol （ISO）诱导的K^+释放减少和环AMP含量增加。随着年龄的增长，对[^3H]二氢阿普萘洛尔结合位点的结合亲和力降低，对[^3H]二氢阿普萘洛尔的结合亲和力增加。膜内胆固醇含量随年龄增长而降低；同时，观察到胆固醇/磷脂比值降低。膜粘度随年龄的增长而降低。心室心肌：随着年龄的增长，特定[^3H]prazosin结合位点的密度降低，对[^3H]prazosin的结合亲和力增加。ne诱导的[^3H]肌醇磷酸的形成随着年龄的增长而减少。随着年龄的增长，胆固醇含量逐渐降低；同时，观察到胆固醇/磷脂比值的降低。膜粘度随年龄的增长而降低。这些结果表明，衰老过程中胆固醇/磷脂比率和/或膜粘度的改变可能解释了肾上腺素能受体信号转导的变化。少

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