Parker I, Ivorra I
Department of Psychobiology, University of California, Irvine 92715.
Proc Natl Acad Sci U S A. 1990 Jan;87(1):260-4. doi: 10.1073/pnas.87.1.260.
Light-flash photolysis of caged inositol 1,4,5-trisphosphate (InsP3) was used to generate reproducible transients of free InsP3 in Xenopus oocytes, and the resulting liberation of Ca2+ from intracellular stores was monitored by recording Ca2+-activated membrane currents and by use of the fluorescent Ca2+ indicator fluo-3. InsP3-mediated Ca2+ release was inhibited by elevating the intracellular free Ca2+ level, either by microinjecting Ca2+ into the cell or by applying conditioning light flashes to liberate Ca2+. This inhibition followed a slow time course, being maximal after about 2 s and subsequently declining over several seconds. Negative feedback of Ca2+ ions on InsP3-mediated Ca2+ liberation may explain the oscillatory release of Ca2+ seen during activation of inositol phospholipid signaling in the oocyte, and the time course of the inhibition is consistent with the period of the oscillations.
利用笼化肌醇1,4,5-三磷酸（InsP3）的闪光光解在非洲爪蟾卵母细胞中产生可重复的游离InsP3瞬变，并通过记录Ca2+激活的膜电流以及使用荧光Ca2+指示剂fluo-3来监测由此导致的细胞内钙库中Ca2+的释放。通过向细胞内微量注射Ca2+或施加预处理闪光以释放Ca2+来提高细胞内游离Ca2+水平，从而抑制InsP3介导的Ca2+释放。这种抑制遵循缓慢的时间进程，在约2秒后达到最大值，随后在数秒内下降。Ca2+离子对InsP3介导的Ca2+释放的负反馈可能解释了卵母细胞中肌醇磷脂信号激活期间所见的Ca2+振荡释放，并且抑制的时间进程与振荡周期一致。
