Age-dependent alteration in cell function of rat salivary glands

本实验研究了大鼠唾液腺中药物受体和核蛋白磷酸化的变化与分泌反应和细胞增殖的关系.用（&lt;^3H&gt;）二氢阿普洛尔和（&lt;^3H&gt;）奎宁环苄酯进行的结合研究表明，大鼠腮腺中的<alpha>-，<beta>-肾上腺素受体和毒蕈碱受体的数量随年龄而变化。然而，这些变化并没有与衰老过程中组织对促分泌素的反应性相结合。的亲和力<beta>-激动剂，而不是<beta>-拮抗剂，<beta>肾上腺素能受体显着改变，随着年龄的增长。亲和力的年龄依赖性变化与组织对β-激动剂的淀粉酶分泌反应有关<beta>。<Alpha_1>腮腺细胞的β-肾上腺素能刺激钾释放随增龄而下降，这种下降可能不是β<alpha_1>-肾上腺素能反应性随增龄而变化的原因。钙外流 ...更多信息 腮腺细胞三磷酸肌醇直接刺激，随年龄增长，其刺激强度降低约50%。差异不是由于老年细胞对磷脂的摄取减少，而是提示三磷酸肌醇从腮腺细胞的细胞内储存中释放钙的能力存在与年龄相关的缺陷.从使用从异丙肾上腺素处理的大鼠中分离的唾液腺细胞核获得的结果可以明显看出，非组蛋白的磷酸化在控制RNA合成的事件中具有重要作用，RNA合成是DNA复制的先决条件。生后大鼠唾液腺细胞核非组蛋白磷酸化水平明显升高。磷酸化水平在4周龄时达到最大值，并下降到16周龄的水平。从出生后12个月的大鼠分离的细胞核中也保持了这种水平。然而，组蛋白磷酸化的任何变化没有观察到随着年龄的增长。非组蛋白磷酸化的年龄依赖性变化与染色质相关的蛋白激酶活性相关。少

Age-dependent alterations of drug receptors and phosphorylation of nuclear proteins in rat salivary glands were studied in relation to the secretory response and the cell proliferation.1. Binding studies with ( <^3H> )dihydroalprenolol and ( <^3H> )quinuclidinyl benzylate showed the age-dependent changes in the number of <alpha> -, <beta> -adrenoceptors and muscarinic receptors in rat parotid glands. However these changes were not coupled with those in responsiveness of the tissues to secretagogues during aging. The affinities of <beta> -agonists, not of <beta> -antagonists, to <beta> -adrenoceptors were significantly changed with increasing age. The age-dependent changes in the affinities were coupled with those in amylase secretory response of the tissues to <beta> -agonists.2. <Alpha_1> -adrenergic stimulated potassium release by parotid cell declined during aging The decline could not be responsible for age-dependent changed in <alpha_1> -adrenergic responsiveness. Calcium efflux s … More timulated directly by inositol triphosphate from parotid cell was reduced by about 50% with increasing age. Differences are not due to a reduction in uptake of the phospholipid into older cells, but suggest and age related defect in the ability of inositol triphosphate to liberate calcium from intracellular store of parotid cells.3. It was obvious from the results obtained by using a salivary gland nuclei isolated from isoproterenol-treated rats that the phosphorylation of the non-histone proteins had an important role in the events controlling the syntheses of RNA which preceeded the replication of DNA. The phosphorylation of non-histone proteins of rat salivary gland nuclei was significantly increased after birth. The levels of phosphorylation reached a maximum at 4-week old rats and declined to those of 16-week old rats. The leveles were also maintained in nuclei isolated from rats of 12 months after birth. However, any changes in the phosphorylation of histone proteins were not observed with increasing age. The age-dependent changes in the phosphorylation of non-histone proteins were coupled with those of protein kinase activities associated with chromatin. Less