Fox A W, Abel P W, Minneman K P
Eur J Pharmacol. 1985 Oct 8;116(1-2):145-52. doi: 10.1016/0014-2999(85)90195-5.
Rings of rat vas deferens and caudal artery were incubated with [3H]inositol in Krebs-Ringer bicarbonate buffer containing 10 mM lithium chloride, and the production of water-soluble [3H]inositol phosphates was monitored. Norepinephrine increased [3H]inositol phosphate accumulation 7-fold in rings from vas deferens and 3-fold in rings from caudal artery. Epinephrine, phenylephrine and methoxamine were as effective as norepinephrine, suggesting that these drugs are full agonists in causing this response. Prazosin, phentolamine and yohimbine completely blocked the stimulation by norepinephrine in both tissues with potencies typical of blockade of alpha 1-adrenoceptors. Despite a substantial receptor reserve for alpha 1-adrenoceptor mediated contractile responses, clonidine, p-amino-clonidine, phenylpropanolamine and ephedrine can only cause a partial contractile response in rat vas deferens. However, all of these partial agonists were either as effective or more effective in increasing [3H]inositol phosphate accumulation in rat vas deferens as they were in activating a contractile response. These data suggest that alpha 1-adrenoceptors increase phosphatidylinositol turnover in rat vas deferens and caudal artery, and that there may be a receptor reserve for alpha 1-adrenoceptor mediated increases in [3H]inositol phosphate accumulation in these smooth muscles.
将大鼠输精管和尾动脉环置于含有10 mM氯化锂的碳酸氢盐缓冲的Krebs-Ringer溶液中，与[3H]肌醇一起孵育，并监测水溶性[3H]肌醇磷酸酯的生成。去甲肾上腺素使输精管环中[3H]肌醇磷酸酯的积累增加7倍，使尾动脉环中增加3倍。肾上腺素、去氧肾上腺素和甲氧明与去甲肾上腺素的作用效果相同，表明这些药物在引发这种反应时是完全激动剂。哌唑嗪、酚妥拉明和育亨宾完全阻断了去甲肾上腺素对两种组织的刺激，其效力具有典型的α1-肾上腺素能受体阻断特征。尽管α1-肾上腺素能受体介导的收缩反应存在大量受体储备，但可乐定、对氨基可乐定、苯丙醇胺和麻黄碱在大鼠输精管中只能引起部分收缩反应。然而，所有这些部分激动剂在增加大鼠输精管中[3H]肌醇磷酸酯积累方面与激活收缩反应一样有效或更有效。这些数据表明，α1-肾上腺素能受体可增加大鼠输精管和尾动脉中磷脂酰肌醇的周转率，并且在这些平滑肌中，α1-肾上腺素能受体介导的[3H]肌醇磷酸酯积累增加可能存在受体储备。
