Down-regulation of Apelin in obesity-related hypertensive rats induced by high-fat diet: Possible role of angiotensin II–AT1R system

(1×10−9 mol/L, 1×10−8 mol/L, 1×10−7 mol/L), respectively. The content of angiotensin II in culture-medium was measured by radioimmunoassay before and after 3, 6,12, and 24 h of using ouabain or ANF (1×10−7 mol/L). Results: Angiotensin II level in Wistar–Kyoto rats was lower than that in SHR. After using ouabain, angiotensin II level of two kinds of rats was remarkably increased, but in Wistar–Kyoto rats angiotensin II level reached the peak after 12 h, while in SHR reached the peak after 6 h. With the increasing concentration of ouabain, angiotensin II level in Wistar–Kyoto rats was increased in a concentration-dependent manner, and in SHR increased in a concentrationindependent manner. After using ANF, the level of angiotensin II of two kinds of rats was significantly increased, but in Wistar–Kyoto rats reached the peak after 3 h, and in SHR increased in a time-dependent manner. As the increase of concentration of ANF, the level of angiotensin II went down in Wistar–Kyoto rats, whereas went up in SHR. Conclusions: Ouabain and ANF influence angiotensin secretion of ASMCs in SHR and Wistar–Kyoto rats. The abnormal regulation of ouabain and ANF secretion in ASMCs may be involved in the pathogenesis of hypertension.