Increased release of atrial natriuretic polypeptides in rats with DOCA-salt hypertension

Abstract

This study compared atrial and plasma concentrations of immunoreactive α-rat atrial natriuretic polypeptide (iα-rANP) in rats given tap water (control), a 1% saline solution (salt), deoxycorticosterone acetate (DOCA) and DOCA plus 1% saline solution (DOCA-salt) after 1 and 8 weeks of treatment. DOCA (100 mg/kg) was given by implanting a piece of silicon rubber impregnated with DOCA subcutaneously. Atrial i α-rANP increased, while plasma iα-rANP decreased with time in all groups. Atrial concentration of iα-rANP was significantly lower in the DOCA-salt group than in the other groups at 1 week, and was reduced in the DOCA and DOCA-salt groups as compared to the control 7 was significantly higher in the DOCA and the DOCA-salt groups than in the control group at 1 week; the DOCA and DOCA-salt group values were also higher than the control and salt group values at 8 weeks. Atrial concentration of iα-rANP was inversely correlated with systolic blood pressure in the all rats at 1 week (r=−0.48, p<0.001) and at 8 weeks (r=−0.33, p<0.05). Plasma concentration of iα-rANP was positively correlated with systolic blood pressure at 8 weeks (r=0.37, p<0.05). In addition, there was a significant positive correlation between plasma/atrial ratio of iα-rANP concentration and systolic blood pressure at either stage (r=0.41, p<0.01 at 1 week; r=0.40, p<0.01 at 8 weeks). Thus, it seems likely that the release of ANPs is increased in response to expansion of extracellular fluid volume or elevation of blood pressure, modifying the development of hypertension in DOCA-salt rats.