Pulmonary extraction of immunoreactive atrial natriuretic factor in dogs

Abstract

A trial natriuretic factor (ANF) is a hormone predominantly secreted by the cardiac atria. It stimulates the kidney to produce natriuresis and diuresis, and vasodilates vascular smooth muscle. The half-life of the hormone is a few minutes, suggesting that breakdown occurs in many tissues.1 Significant extraction of ANF has been demonstrated across the capillary beds of liver, kidney and limb.1-3 Pulmonary extraction of the hormone has not been shown in dogs3 or man,1,2 however, even though rat lung homogenates destroy ANF4 and isolated rabbit lungs remove ANF,5 perhaps because blood samples in the in vivo studies were obtained from systemic arteries instead of pulmonary veins. If ANF is released into the left atrial cavity through the thebesian veins, systemic arterial sampling could underestimate pulmonary extraction of ANF. The purpose of this study was to determine whether ANF is extracted across the canine pulmonary perfusion bed.