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 (αh-ANP) has been studied in normal man by radioimmunoassay of the atrial peptide in plasma and plasma extracts. After an intravenous (iv) bolus injection of 100μg αh-ANP, levels of immunoreactive αh-ANP (IR-αhANP) in unextracted plasma fell rapidly and exponentially during the first 10 min ( t 1 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-αhANP under steady state conditions of constant iv infusion (200μg 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-αhANP was 3.1 min.