AGE RELATED CHANGES IN ADRENERGIC CLINICAL PHARMACOLOGY

这项提案的主要目标是界定 发生在人类中的与年龄相关的变化的位置和机制 外周肾上腺素能神经系统。我们假设与年龄有关的 变化仅限于受神经支配的β-肾上腺素受体。 1)老年人肾上腺素能神经系统发生了哪些与年龄相关的变化 人类？我们推测血浆中增加的去甲肾上腺素 老年人的注意力集中部分是由于肾上腺素能有缺陷。 神经元摄取。我们计划量化神经元对去甲肾上腺素的摄取 通过测定地塞帕明对去甲肾上腺素清除的影响。我们 还假设压力感受器功能随年龄变化不大。我们 计划通过测定血浆来测试压力感受器功能 去甲肾上腺素对药物引起的血液变化的反应 压力。 因为我们之前的数据表明，与年龄相关的变化 肾上腺素能功能仅限于含有神经的组织 β-肾上腺素能受体，我们将研究被神经支配的 儿茶酚胺测定人脂肪细胞上的β-肾上腺素能受体 体内和体外刺激的脂解作用。作为回应的cAMP积累 β-肾上腺素能受体激动剂、NaF和Forsklin将在 分离的人类脂肪细胞。 我们计划对其药代动力学和药效学进行研究。 哌唑嗪与心得安在青年和老年人中的立体异构体 作为我们先前研究的后续研究的健康志愿者。 2)这些变化的轨迹和机制是什么？最近的报道 提示内源性腺苷可能是减少 老年动物的β-肾上腺素能受体反应。我们计划对此进行测试 通过确定茶碱对人的影响来确定在人类中的可能性 β-肾上腺素能受体刺激的心脏变时性反应。 我们将研究β-肾上腺素能受体的密度 单核白细胞的每个亚群来解释我们的 之前的观察表明，老年人的心脏重量增加了2.5倍 单核细胞膜上的β-肾上腺素受体密度。单元格 将通过每个群体亚型与免疫磁性的结合来分离 珠子。 我们将描述人类脂肪细胞的β-肾上腺素能受体 亚型(S)，通过测定受体密度、拮抗剂亲和力和 腺酰环化酶催化亚单位与受体的偶联 通过激动剂高亲和力状态和低亲和力状态的比率进行评估。 碘化吲哚将被用作放射性配体；激动剂和 竞争约束性研究的拮抗剂将基于他们的 β肾上腺素能受体亚型的特异性。我们将决定 人类受体后事件是否发生与年龄相关的变化 评估蛋白质磷酸化对脂肪细胞的影响 异丙肾上腺素、福斯可林和二丁酰环AMP。细胞内的ATP将会是 用~(32)P和磷酸化多肽预标记法检测 十二烷基硫酸钠-PAGE凝胶放射自显影。这些研究将与 功能研究。

The major objectives of this proposal are to define the nature, extent, locus, and mechanism of age-related changes that occur in the human peripheral adrenergic nervous system. We postulate that age-related changes are limited to innervated beta-adrenoceptors. 1) What age-related changes occur in the adrenergic nervous system of humans? We postulate that the increased plasma norepinephrine concentration in the elderly is due, in part, to a defect in adrenergic neuronal uptake. We plan to quantify neuronal uptake of norepinephrine by determining the effect of desipramine on norepinephrine clearance. We also postulate that baroreceptor function is little changed with age. We plan to test baroreceptor function by determining the plasma norepinephrine response to pharmacologically induced changes in blood pressure. Since our previous data indicate that age-related changes in adrenergic function are limited to tissues that contain innervated beta-adrenoceptors, we will investigate the function of the innervated beta-adrenoceptor on human fat cells by determining catecholamine stimulated lipolysis in vivo and in vitro. cAMP accumulation in response to beta-adrenoceptor agonist, NaF, and forskolin will be determined in isolated human adipocytes. We plan to study the pharmacokinetics and pharmacodynamics of prazosin and the stereoisomers of propranolol in young and elderly healthy volunteers as a followup to our previous studies. 2) What is the locus and mechanisms of these changes? Recent reports suggest that endogenous adenosine may be responsible for reduced beta-adrenoceptor responses in elderly animals. We plan to test this possibility in humans by determining the effect of theophylline on the cardiac chronotropic response to beta-adrenoceptor stimulation. We will investigate the density of the beta-adrenoceptor on each subpopulation of mononuclear leukocyte in order to explain our previous observation that the elderly have a 2.5 fold increase in beta-adrenoceptor density on their mononuclear cell membranes. Cells will be separated by binding of each population subtype to immunomagnetic beads. We will characterize the human adipocyte beta-adrenoceptor subtype(s) by determining receptor density,, antagonist affinity, and coupling of the receptors to the catalytic subunit of adenylyl cyclase as assessed by the ratio of the agonist high and low affinity states. Iodinated pindolol will be used as the radioligand; agonists and antagonists for competition binding studies will be based on their specificity for the beta-adrenoceptor subtypes. We will determine whether age-related changes occur in post-receptor events in the human adipocyte by assessing protein phosphorylation in response to isoproterenol, forskolin, and dibutyryl cyclic AMP. Cellular ATP will be prelabelled with 32Pand phosphorylated peptides detected by autoradiographs of SDS-PAGE gels. These studies will be correlated with the functional studies.