Schnetkamp P P
Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
Biochemistry. 1987 Jun 16;26(12):3249-53. doi: 10.1021/bi00386a002.
Guanosine cyclic 3',5'-phosphate (cGMP) induced Ca2+ release from bovine rod outer segment (ROS) disks showed two kinetic components that could be distinguished in three ways: (1) The slow component (half-rise time of about 30 s) was blocked by 1-cis diltiazem [cf. Koch, K. W., & Kaupp, U. B. (1985) J. Biol. Chem. 260, 6788-6800], whereas the fast component (half-rise time of less than 1 s) was not affected by 1-cis diltiazem. (2) The slow component required the presence of alkali cations, whereas the fast component did not. (3) Preincubation with Na+ (50 mM) selectively eliminated the fast component, whereas the slow component was not affected. The action of Na+ appeared to be caused by Na-Ca exchange removing Ca2+ from a pool that can also be accessed by cGMP. The slow component of cGMP-induced Ca2+ release was not affected by Na+ and, hence, appears to reside in disks that do not contain a functional Na-Ca exchanger. The local anesthetic tetracaine blocked both the slow and fast component of cGMP-induced Ca2+ release from bovine ROS disks.
3',5'-环磷酸鸟苷（cGMP）诱导的牛视杆外段（ROS）盘内Ca2+释放呈现出两个动力学成分，可通过三种方式加以区分：（1）慢成分（半上升时间约为30秒）被1-顺式地尔硫卓阻断[参见Koch, K. W., & Kaupp, U. B. (1985) J. Biol. Chem. 260, 6788 - 6800]，而快成分（半上升时间小于1秒）不受1-顺式地尔硫卓影响。（2）慢成分需要碱金属阳离子的存在，而快成分则不需要。（3）用Na+（50 mM）预孵育可选择性消除快成分，而慢成分不受影响。Na+的作用似乎是由Na-Ca交换将Ca2+从一个也可被cGMP作用的池中移除所致。cGMP诱导的Ca2+释放的慢成分不受Na+影响，因此似乎存在于不含有功能性Na-Ca交换体的盘内。局部麻醉药丁卡因阻断了cGMP诱导的牛ROS盘内Ca2+释放的慢成分和快成分。
