Angiotensin II stimulated the breakdown of phosphatidylinositol-4,5-bisphosphate (PIP2) and the generation of inositol trisphosphate (IP,) in cultured rat aortic smooth muscle cells. The decrease in PIP2 and increase in IP, levels were rapid (measurable at 5 seconds; maximum IP, levels at 15 seconds). The time course of these changes was comparable to that of angiotensin Il-induced increases in...

Pig oocytes matured in vitro are parthenogenetically activated after treatment with nitric oxide (NO)-donor SNAP. The chelation of intracellular calcium ions with BAPTA-AM suppressed the SNAP-induced activation in a dose-dependent manner. Activation by a NO-donor is dependent on the influx of calcium from extracellular spaces, because the blockage of calcium channels by verapamil had significan...

The early effects of 1,25 dihydroxyvitamin D [1,25 (OH)2D] on calcium transfer in and out of the skeleton were studied in rats to determine whether mobilized bone calcium was reutilized during new bone mineralization. Vitamin-D deficient rats were labeled with 45calcium 10 to 14 days prior to treatment (experiment 1) or at the same time (experiment 2) they were injected with 0.125 microgram of ...

Acrosomal exocytosis is a calcium-regulated exocytosis that can be triggered by PKC activators. The involvement of PKC in acrosomal exocytosis has not been fully elucidated, and it is unknown if MARCKS, the major substrate for PKC, participates in this exocytosis. Here, we report that MARCKS is expressed in human spermatozoa and localizes to the sperm head and the tail. Calcium- and phorbol est...

Calcium is a pleiotropic messenger controlling a diverse array of intracellular events from fertilization to cell death. One of the main mechanisms by which intracellular calcium is elevated is through InsP(3) [Ins(1,4,5)P(3)]-induced mobilization of calcium from its receptor on the endoplasmic reticulum calcium store. The activity of the InsP(3)R (InsP(3) receptor) is subject to regulation by ...

Angiotensin II stimulated the breakdown of phosphatidylinositol-4,5-bisphosphate (PIP2) and the generation of inositol trisphosphate (IP3) in cultured rat aortic smooth muscle cells. The decrease in PIP2 and increase in IP3 levels were rapid (measurable at 5 seconds; maximum IP3 levels at 15 seconds). The time course of these changes was comparable to that of angiotensin II-induced increases in...