Effect of U-73122 on calcium channel activity in porcine myometrial cells and pancreatic beta-cell line RINm5F.
OBJECTIVE
To study the effect of U-73122, putative phospholipase C (PLC) inhibitor, on cytosolic Ca2+ concentration ([Ca2+]i) and voltage-dependent calcium channels (VDCC).


METHODS
To record whole cell calcium current (ICa) by perforated patch-clamp and to measure cytosolic free calcium concentration ([Ca2+]i) with Fura-2.


RESULTS
U-73122 inhibited KCl-induced and Bay-K-8644-induced increase in [Ca2+]i dose-dependently. U-73122 decreased markedly depolarization-induced ICa both in RINm5F and porcine myometrial cells in a concentration-dependent manner. The effect of U-73122 was more potent in porcine myometrial cells than that in RINm5F cells. U-73343 (an analog of U-73122), that does not inhibit PLC, also reduced the ICa by 50%.


CONCLUSIONS
U-73122 inhibited VDCC and [Ca2+]i in both RINm5F and porcine myometrial cells.
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects*; D002478:Cells, Cultured; D004963:Estrenes / Q000494:pharmacology*; D005260:Female; D007340:Insulinoma / Q000473:pathology; D009215:Myometrium / Q000166:cytology; D010190:Pancreatic Neoplasms / Q000473:pathology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D011760:Pyrrolidinones / Q000494:pharmacology*; D051381:Rats; D013552:Swine; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors