IEPA.d8.s14
The objectives of this study were to evaluate and compare the actions of endothelin-1 (ET-1), oxytocin, prostaglandin F2 alpha (PGF2 alpha) and inositol 1,4,5-trisphosphate (IP3) on 45Ca2+ mobilization in permeabilized rat myometrial cells and to examine the activation of the inositol lipid cycle in intact myocytes
IEPA.d8.s15
All four agonists caused a biphasic release of 45Ca2+ from non-mitochondrial pool(s), with the rank order of potency: oxytocin > PGF2 alpha > ET-1 > IP3
IEPA.d8.s16
Endothelin-1 and oxytocin stimulated inositol phosphate accumulation at concentrations similar to those that promoted 45Ca2+ efflux, whereas about 100 times higher concentrations of PGF2 alpha were needed to activate this signaling pathway in intact cells
IEPA.d8.s17
It is concluded that the primary action of PGF2 alpha in myometrial cells is to enhance Ca2+ influx, whereas oxytocin and ET-1 receptors are coupled to phospholipase C, generating IP3 and raising the intracellular concentration of free Ca2+ from intracellular as well as extracellular sources