ATRIAL-NATRIURETIC-PEPTIDE AND PLASMA-VOLUME OF DOGS SUFFERING FROM HEART OR DEHYDRATION

Studies in humans and experimental animal models suggest that volume o verload increases and volume underload decreases release of atrial nat riuretic peptide (ANP), a hormone intimately linked to water and elect rolyte homeostasis. This relationship was examined in dogs suffering f rom heart failure or dehydration and the data presented here are in su pport of this general concept. Plasma ANP concentration in dogs with c ongestive heart failure (CHF) was elevated with the severity of the di sease (NYHA classification, class II: 21.4 +/- 9.2 fmol ANP/ml; class III: 65.5 +/- 72.6; class IV: 119.7 +/- 87.1; healthy dogs: 13.9 +/- 7 .5). The increment in plasma ANP concentration in cardiac patients was also positively correlated with the plasma volume. The blood volume o f dogs with moderate and severe CHF was significantly (P < 0.05) eleva ted and a normotonic blood pressure prevailed. In contrast, dehydrated dogs tend to display reduced ANP plasma concentration (7.7 +/- 5.6 fm ol/ml) as well as significantly lower plasma volume and reduced blood pressure (P < 0.05). In dogs with severe CHF, ANP precursor material i s present in the blood, which is normally undetectable. These data fur ther support the concept of a regulatory function of ANP in volume hom eostasis of dogs.