EFFECTS OF 2,5-DI(TERT-BUTYL)-1,4-HYDROQUINONE, AN ENDOPLASMIC-RETICULUM CA2-ATPASE INHIBITOR, ON AGONIST-STIMULATED PHASIC MYOMETRIAL CONTRACTIONS()

Phasic myometrial contractions utilize mechanisms involving the cyclin g of calcium into and out of intracellular calcium stores. These studi es were performed to determine the effects of 2.5-di(tert-butyl)-1,4-h ydroquinone (tBHQ), an endoplasmic reticulum Ca2+-ATPase inhibitor, on in vitro isometric myometrial contractions. These studies demonstrate d that low concentrations of tBHQ (eg. 10 mu M) appear to inhibit intr acellular calcium cycling,whereas higher concentrations also inhibit e xtracellular calcium influx. These combined tBHQ effects markedly supp ressed myometrial contractions stimulated in response to various agoni sts including oxytocin, PGF(2 alpha), KCl, ionomycin, and Bay K 8644. (C) 1995 Academic Press, Inc.