Effects of Bay K 8644, a voltage-sensitive calcium channel agonist, on atrial natriuretic polypeptide (ANP) secretion from isolated rat hearts perfused with Krebs-Henseleit solution were investigated. After a ninetymin period for stabilization, coronary sinus effluents were collected every two min and ANP levels were measured by radioimmunoassay. The basal secretory rate of ANP was 1.65 ± 0.15 ng/min (mean ± standard error). Bay K 8644 stimulated ANP secretion dose-dependently. This stimulatory action was blocked by simultaneous administration of nifedipine, its competitive antagonist. Heart rate was also increased by Bay K 8644 administration. In the gel filtration study, the major secretory form of ANP corresponded to α-rat ANP, a 28-amino acid peptide. These results suggest that voltage-sensitive calcium channels are involved in two principal biological properties, contraction and ANP secretion, of atrial cardiocytes.
|Biochemical and Biophysical Research Communications
|Published - 1986 8月 14
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