| Summary: | Through the actions of bradykinin (BK) and angiotensin II (ANG II), the kallikrein-kinin and renin-angiotensin systems, respectively, regulate cardiovascular mechanisms in both mammals and fish. The myotropic and cardiovascular actions of homologous BK from the little skate, Leucoraja erinacea, were examined in the little skate. Administration of skate BK in vivo produced a biphasic increase in blood pressure and constricted the 1st branchial, mesenteric and celiac arteries in vitro. Co-administration of skate BK with several pharmacological agents suggest multiple pathways are involved in mediating the myoactivity of the BK in the little skate. The myotropic effects of ANG peptides were also assessed in the little skate and addition of homologous ANG II to pre-constricted vessels in vitro demonstrated a dose-dependent vasodilation. Morover, addition of skate BK in a heterologous bioassay produced a dose-dependent vasodilator effect in the aorta of the mouse suggesting conservation of this ancient peptide-receptor complex in mammals.
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