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pubmed:abstractText |
Exposure of cultured, spontaneously beating rat cardiomyocytes to arginine vasopressin (AVP) led to marked increases in the release of prostacyclin (PGI2) and atrial natriuretic peptide (ANP). These responses were accompanied by a rapid, transient rise of cytosolic free Ca2+ concentration ([Ca2+]i) and of membranous protein kinase C (PKC) activity. Ca2+ influx and PKC activity appeared to play important but distinct roles in AVP-induced cellular responses, insofar as only AVP-induced ANP secretion was abolished by the Ca2+ channel antagonist nifedipine, whereas both AVP-induced PGI2 production and ANP release were abolished by the PKC inhibitors staurosporine and CGP-41251. The AVP-induced increase in [Ca2+]i could also be mimicked with the vasopressin (V1-subtype) agonist Octapressin, but not with the V2-agonist 1-desamino-8-D-arginine vasopressin, and was fully abolished by the V1-antagonist [d(CH2)5Tyr(Me)]AVP, but not by d(CH2)5-D-Leu-VAVP (V1-/V2-antagonist). These results indicate that V1-vasopressinergic receptors mediate AVP-induced PGI2 production and ANP secretion in rat cardiomyocytes and that, whereas both Ca2+ influx and PKC activation are required for AVP-induced ANP secretion, AVP-induced PGI2 formation is mainly regulated by PKC.
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