METABOLIC-CLEARANCE RATE AND PLASMA HALF-LIFE OF ALPHA-HUMAN ATRIAL-NATRIURETIC-PEPTIDE IN MAN

The disappearance and metabolic clearance rate (MCR) of alpha human atrial natriuretic peptide (.alpha.h-ANP)has been studied in normal man by radioimmunoassy of the atrial peptide in plasma and plasma extracts. After an intravenuous (iv) bolus injection of 100 .mu.g .alpha.h-ANP, levels of immunoreactive .alpha.h-ANP (IR-.alpha.hANP) in unextracted plasma fell rapidly and exponentially during the first 10 min (t1/2 = 2.5 min), after which levels declined more slowly to reach basal values 30 min after injection. Venous plasma extracts, purified by Sep Pak cartridges, were used to calculate the MCR of IR -.alpha.hANP under steady state conditions of constant iv infusion (200 .mu.g over 60 min) in healthy volunteers. Calculated MCR from venous samples was 2.4 L/min and volume of distribution 10.7 L. After cessation of infusions, the disappearance rate (rapid phase) of IR-.alpha.hANP was 3.1 min.