INCREASED PLASMA BRAIN NATRIURETIC PEPTIDE LEVELS IN DOCA SALT HYPERTENSIVE RATS - RELATION TO BLOOD-PRESSURE AND CARDIAC CONCENTRATION

Four experimental groups of rats treated with 1{circled} DOCA-salt, 2{circled} DOCA or 3{circled} salt, and {circled digit four} controls were used to study the participation of brain natriuretic peptide (BNP) in the development of hypertension. Plasma and cardiac tissue concentrations of BNP as well as atrial natriuretic peptide (ANP) were measured in each group by using radioimmunoassays specific to rat BNP or ANP. Plasma BNP levels in DOCA-salt hypertensive group were higher than those in control (p<0.01). salt (p<0.01) and DOCA (p<0.01) groups. A positive correlation was observed between plasma BNP levels and blood pressure (r=0.70, p<0.001) and between plasma ANP levels and blood pressure (r=0.62, p<0.001). Plasma BNP/ANP ratio increased parallel with elevation of blood pressure. Plasma BNP levels correlated negatively with atrial BNP concentration (r=-0.33, p<0.05), but positively with ventricular BNP (r=0.76, p<0.001). Compared with controls, tissue BNP-45/γ-BNP ratio in the DOCA-salt rats was lower in atrium, but higher in ventricle. Thus, in DOCA-salt hypertension atrial BNP decreased with exhaustion of stored BNP-45, while ventricular BNP increased as BNP-45 accumulated. These results suggest that BNP is a novel cardiac hormone, synthesized, processed and secreted in response to changes in blood pressure. BNP may play different roles in controlling blood pressure than those assumed by ANP. © 1990 Academic Press, Inc.