Effects of Norepinephrine and Neuropeptide Y on the Contractility of Small Mesenteric Artery from 2K1C and DOCA-Salt Hypertensive Rats

Effects of Norepinephrine and Neuropeptide Y on the Contractility of Small Mesenteric Artery from 2K1C and DOCA-Salt Hypertensive Rats

<P> The present study was conducted to investigate the possible role of the sympathetic nervous system in two-kidney, one clip (2K1C) and deoxycorticosterone acetate (DOCA)-salt hypertension. 2K1C and DOCA- salt hypertension were made in Sprague-Dawley rats. Four weeks after induction of hypertension, systolic blood pressure measured in conscious state was significantly higher in 2K1C (216&#8273;18 mmHg) and DOCA-salt (205&#8273;29 mmHg) groups than that in control (128&#8273;4 mmHg). The third branches (＜300 μm in outer diameter) of the mesenteric artery were isolated and cut into ring segments of 2∼3 mm in length. Each ring segment was mounted in tissue bath and connected to a force displacement transducer for measurement of isometric tension. The arterial rings were contracted by application of norepinephrine (NE) in a dose-dependent manner. The amplitude of the NE-induced contraction of the vessels was significantly larger in hypertension than in control. The NE-induced contraction was significantly enhanced by neuropeptide Y (NPY) in hypertension. Reciprocally, NPY-elicited vasocontraction was increased by NE in hypertension. These results suggest that the sympathetic nervous system contributes to the development of 2K1C and DOCA-salt hypertension.