Wright HM, Malik KU. Prostacyclin synthesis elicited by endothelin-1 in rat aorta is mediated by an ETA receptor via influx of calcium and is independent of protein kinase C.
Hypertension 1995;
26:1035-40. [PMID:
7498963 DOI:
10.1161/01.hyp.26.6.1035]
[Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The purpose of this study was to characterize the receptor(s) and second messenger systems involved in prostacyclin (prostaglandin [PG] I2) synthesis elicited by endothelin (ET)-1 in the rat aorta. PGI2 synthesis, measured as immunoreactive 6-keto-PGF1 alpha, was assessed in aortic rings exposed to endothelin receptor agonists in the presence and absence of selective ETA and ETB receptor antagonists. ET-1, which has equal affinity for both endothelin receptor subtypes, and ET-3, a preferential ETB receptor agonist, enhanced 6-keto-PGF1 alpha synthesis in a time- and concentration-dependent manner. ET-1 was more potent than ET-3 in increasing 6-keto-PGF1 alpha synthesis. Moreover, the selective ETB receptor agonists IRL-1620 and sarafotoxin S6c did not significantly increase 6-keto-PGF1 alpha synthesis. Furthermore, ET-1-induced 6-keto-PGF1 alpha synthesis was attenuated by an ETA receptor antagonist, BQ-123, in a dose-dependent manner but not by an ETB receptor antagonist, BQ-788. Depletion of extracellular Ca2+ or addition of Ca2+ channel blockers (nifedipine, verapamil, SK&F 96365) attenuated ET-1-mediated 6-keto-PGF1 alpha synthesis, while a Ca2+ channel agonist, S(-)-Bay K 8644, potentiated this effect of ET-1. Selective protein kinase C inhibitors (bisindolylmaleimide I, calphostin C) did not alter ET-1-induced 6-keto-PGF1 alpha synthesis. These data suggest that PGI2 synthesis elicited by ET-1 in the rat aorta is mediated primarily through influx of extracellular Ca2+ via activation of an ETA receptor and is independent of protein kinase C.
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