Zhang Z D, Kwan C Y, Daniel E E
Department of Biomedical Sciences, McMaster University Health Sciences Centre, Hamilton, Canada.
Biol Signals. 1993 Sep-Oct;2(5):284-92. doi: 10.1159/000109509.
Ca2+ plays an important role in muscle contraction. Two major Ca2+ release channels have been suggested to be present in smooth muscle by functional studies: one is sensitive to inositol 1,4,5-trisphosphate (IP3) and the other is operated by Ca2+ and also sensitive to ryanodine. The existence of these two channels in smooth muscle has been confirmed recently by radioligand binding studies using subcellular membrane and named IP3 and ryanodine receptors. The isolated IP3 and ryanodine receptors from smooth muscles show a channel activity and can be operated by IP3 and ryanodine, respectively. Some similarities of these two receptors have been noted at the molecular level, but they are most likely to be two separate proteins. Although both channels are believed to be involved in regulating cytosol Ca2+ level in smooth muscle, their relative importance in different smooth muscles is still not very clear.
钙离子（Ca2+）在肌肉收缩中起着重要作用。功能研究表明，平滑肌中存在两种主要的钙离子释放通道：一种对肌醇1,4,5-三磷酸（IP3）敏感，另一种由钙离子调控且对ryanodine敏感。最近，通过使用亚细胞膜的放射性配体结合研究证实了平滑肌中这两种通道的存在，并将其命名为IP3受体和ryanodine受体。从平滑肌中分离出的IP3受体和ryanodine受体显示出通道活性，且分别可由IP3和ryanodine调控。在分子水平上已注意到这两种受体存在一些相似之处，但它们很可能是两种不同的蛋白质。尽管人们认为这两种通道都参与调节平滑肌中的胞质钙离子水平，但它们在不同平滑肌中的相对重要性仍不太清楚。
