CARDIAC CONTENT OF BRAIN NATRIURETIC PEPTIDE IN DOCA-SALT HYPERTENSIVE RATS

The cardiac content of immunoreactive rat brain natriuretic peptide (ir-rBNP) in deoxycorticosterone acetate (DOCA) -salt hypertensive rats was measured by radioimmunoassay (RIA). The atrial content of ir-rBNP was significantly lower in the DOCA-salt group than in the control group (p < 0.01). However, the ventricular content of ir-rBNP was markedly increased in the DOCA-salt group as compared to the other groups. Ir-rBNP levels in the atria was negatively correlated with blood pressure (r = -0.49, p < 0.01), while that in the ventricle was positively correlated with blood pressure (r = 0.79, p < 0.001). A significant correlation was observed between tissue levels of ir-rBNP and ir-rat atrial natriuretic peptide (rANP) both in atrium and ventricle (atrium, r = 0.63, p < 0.001 ; ventricle, r = 0.95, p < 0.001). These results raise the possibility that rBNP as well as rANP functions as a cardiac hormone, the production of which probably changes in response to increased of body fluid and blood pressure.