EFFECTS OF INTRAVENOUSLY ADMINISTERED C-TYPE NATRIURETIC PEPTIDE IN HUMANS - COMPARISON WITH ATRIAL-NATRIURETIC-PEPTIDE

We have previously reported that C-type natriuretic peptide (CNP), the third member of the natriuretic peptide family, is produced in vascul ar endothelial cells and suggested that CNP might be a local regulator of vascular tone and growth. To evaluate the biological actions of CN P as compared with human a-trial natriuretic peptide (hANP), we intrav enously administered synthetic CNP (0.43 nmol/kg) and alpha-hANP (0.43 and 0.043 nmol/kg) to healthy humans. The experiments were done on di fferent days in the same five healthy volunteers (31 +/- 1 yr old). CN P injection caused a transient but significant decrease in both systol ic and diastolic blood pressure (-4.3 +/- 1.3, -4.1 +/- 1.0 mmHg) with a significant increase in heart rate (+7.6 +/- 2.6 bpm), and exerted significant diuretic and natriuretic activities (+130 +/- 80%, +160 +/ - 100% over the basal level). These effects of CNP (0.43 nmol/kg) were comparable to, or less than, those of alpha-hANP (0.043 nmol/kg), CNP injection also significantly suppressed aldosterone secretion (22% re duction as compared with the basal le vel). Our results demonstrate th at intravenously-administered CNP acts as a natriuretic peptide with l ess potency than ANP.