Plasma immunoreactive atrial natriuretic peptide levels after subcutaneous alpha-hANP injection in normal humans

The plasma hormone and urine effects of 100 micrograms of alpha-human atrial natriuretic peptide (alpha-hANP) given by subcutaneous (s.c.) injection, were studied in eight healthy male volunteers. A control s.c. injection was administered on a separate day, and the study was single-blind. The peak immunoreactive atrial natriuretic peptide (IR-ANP) level of 29.4 +/- 4.4 pmol/L reached at 5 min was threefold higher than on the control day. Area under the IR-ANP response curve was approximately 1/32 of that after the same dose of alpha-hANP given by intravenous (i.v.) injection. alpha-hANP s.c. injection was not associated with significant effects on plasma renin activity (PRA), plasma aldosterone, or urine electrolyte excretion. It was concluded that only a small percentage of intact alpha-hANP is absorbed into the circulation after s.c. injection. With the dose of peptide and the injection vehicle chosen, alpha-hANP had little or no biological effect.