Karaki H, Weiss G B
Gastroenterology. 1984 Oct;87(4):960-70.
It appears that, in smooth muscle, there are two distinct types of Ca2+ channel, a voltage-dependent Ca2+ channel and a receptor-linked Ca2+ channel. The former is activated by decreases in membrane potential and the latter is regulated by drug-receptor interactions. These Ca2+ channels exist as separate channels in the aorta of the adult rabbit and of some rat strains; organic Ca2+ antagonists and sodium nitroprusside selectively inhibit each of these two respective channels. By examining the effects of these two specific antagonists, characterization of the Ca2+ channels in other types of smooth muscle was attempted. In a wide variety of vascular smooth muscle (except aorta of above-mentioned animals), however, these two Ca2+ channels showed some sensitivity to both types of inhibitor. It is proposed that in most types of vascular smooth muscle as well as in gastric fundus and corpus, the two types of Ca2+ channel are functionally not completely separated. These subtypes of Ca2+ channels are at least partly sensitive to both organic Ca2+ antagonists and sodium nitroprusside. Intestinal, genital, and tracheal smooth muscles also seem to have two types of Ca2+ channel. These subtypes of Ca2+ channels are, however, sensitive only to organic Ca2+ antagonists and are not affected by sodium nitroprusside.
在平滑肌中，似乎存在两种不同类型的钙通道，即电压依赖性钙通道和受体偶联钙通道。前者由膜电位降低激活，后者受药物 - 受体相互作用调节。这些钙通道在成年兔和某些大鼠品系的主动脉中以独立通道形式存在；有机钙拮抗剂和硝普钠分别选择性抑制这两种通道。通过研究这两种特异性拮抗剂的作用，尝试对其他类型平滑肌中的钙通道进行表征。然而，在多种血管平滑肌（上述动物的主动脉除外）中，这两种钙通道对两种抑制剂均表现出一定敏感性。有人提出，在大多数类型的血管平滑肌以及胃底和胃体中，这两种钙通道在功能上并未完全分离。这些钙通道亚型至少部分对有机钙拮抗剂和硝普钠敏感。肠道、生殖器官和气管平滑肌似乎也有两种钙通道。然而，这些钙通道亚型仅对有机钙拮抗剂敏感，不受硝普钠影响。
