Direct effect of endothelin-1 on the granuloma cells of the porcine ovary.
Specific binding sites for endothelin-1 (ET-1), a novel potent vasoconstrictor peptide, as well as the effects of ET-1 on cytosolic free Ca2+ concentration ([Ca2+]i), intracellular total inositol phosphate (IP) generation and steroidogenesis were studied in cultured porcine granulosa cells. Scatchard analysis of a binding study using 125I-labelled ET-1 indicated the presence of a single class of high-affinity binding sites with almost equal affinity for ET-1 and ET-3: the apparent dissociation constant was 0.59 nmol/l and the maximal binding capacity was 1.84 pmol/mg protein. Affinity-labelling of 125I-labelled ET-1 to the membranes using disuccinimidyl tartarate as a cross-linker revealed one major and one minor band with the apparent molecular weights of 32 kDa and 49 kDa respectively. ET-1 dose-dependently (1-100 nmol/l) induced rapid and transient increases in [Ca2+]i in fura-2-labelled cells. ET-1 also dose-dependently stimulated total IPs in cells prelabelled with myo-[3H]inositol. ET-1 had a slight stimulatory effect on the secretion of progesterone but not of oestradiol from porcine granulosa cells. The present data clearly demonstrate the presence of a non-selective ET receptor (ETB) in porcine granulosa cells coupled with phosphoinositide hydrolysis and [Ca2+]i mobilization, and suggest that ET-1 may play some role in the production of progesterone by porcine granulosa cells.
Kamada
S
S
Department of Obstetrics and Gynecology, Tokyo Medical and Dental University, Faculty of Medicine, Japan.
Kubota
T
T
Hirata
Y
Y
Taguchi
M
M
Eguchi
S
S
Marumo
F
F
Aso
T
T
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D016232:Endothelins / Q000378:metabolism / Q000494:pharmacology*; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D007295:Inositol Phosphates / Q000096:biosynthesis; D011374:Progesterone / Q000096:biosynthesis; D013552:Swine / Q000378:metabolism*
D016232:Endothelins; D007295:Inositol Phosphates; D011374:Progesterone; D000242:Cyclic AMP; D002118:Calcium