Meisheri K D, Hwang O, van Breemen C
J Membr Biol. 1981 Mar 15;59(1):19-25. doi: 10.1007/BF01870817.
The activation of rabbit aortic smooth muscle was studied by two most widely used vascular smooth muscle stimulants: alpha-adrenoceptor activation by norepinephrine (NE) and high-K+ depolarization. This was studied by measurements of isometric contractions and net as well as unidirectional Ca2+ fluxes. These parameters showed markedly differential sensitivities towards tow smooth muscle inhibitors used in this study: D600 and amrinone. By choosing an appropriate concentration of D600 or amrinone, Ca2+ uptake or Ca2+ influx induced by high K+ or NE could by selectively inhibited. Furthermore, by using unidirectional flux measurements it was demonstrated that Ca2+ influx stimulated by NE and high K+ were additive in nature. The data from the addivity experiment exclude the interpretation of a common Ca2+ pathway with two separate mechanisms for opening it. The data on three criteria employed in this study provide evidence for the existence of two independent Ca2+ pathways, one for each mode of activation, for Ca2+ influx known to be associated with these contractions.
去甲肾上腺素（NE）激活α-肾上腺素能受体以及高钾去极化。通过测量等长收缩以及净钙通量和单向钙通量来进行此项研究。这些参数对本研究中使用的两种平滑肌抑制剂：D600和氨力农表现出明显不同的敏感性。通过选择合适浓度的D600或氨力农，可以选择性抑制高钾或NE诱导的钙摄取或钙内流。此外，通过使用单向通量测量表明，NE和高钾刺激的钙内流本质上是相加的。相加性实验的数据排除了存在一个共同的钙通道但有两种不同开放机制的解释。本研究中采用的三项标准的数据为存在两条独立的钙通道提供了证据，每种激活模式各有一条，用于已知与这些收缩相关的钙内流。
