Abstract
In the present study, we examined the effect of atrial natriuretic peptide (ANP) on Ca 2+ efflux from freshly isolated adult rat cardiomyocytes. Rat ANP(1–28) stimulated the efflux of 45Ca 2+ from the cells in a concentration-dependent manner (10 −8 M to 10 −6 M). The 45Ca 2+ efflux was not affected by removal of extracellular Ca 2+, but was dependent on the presence of extracellular Na +. In addition, rat ANP(1–28) caused 22Na + influx into the cells. The 45Ca 2+ efflux was also stimulated by C-type natriuretic peptide-22 (CNP-22), but not by rat brain natriuretic peptide-45 (BNP-45). It was also observed that both rat ANP(1–28) and CNP-22 stimulated guanosine 3′,5′-cyclic monophosphate production within the cells. These results indicate that ANP stimulates Na +-dependent 45Ca 2+ efflux from freshly isolated adult rat cardiomyocytes, probably through Na +/Ca 2+ exchange, and that the stimulatory effect of ANP on Ca 2+ efflux may be mediated via the natriuretic peptide receptor which has been shown to couple to guanylate cyclase. Since it is reported that Na +/Ca 2+ exchange is important in calcium homeostasis within cells, ANP may play a role in the extrusion of intracellular Ca 2+ from isolated adult rat cardiomyocytes.
Published Version
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