Jpn. J. Pharmacol. 85 (1), 109-113 (2001)

Is Compensatory Vasoconstrictor Tone in the Hindquarter Vascular Region Induced by Hemorrhage in Conscious Spontaneously Hypertensive Rats?

Yasuhiro Teranishi^1,*, Noriko Iida¹, Norio Ishioka², Hiroshi Sugino² and Taku Amano<sup>3

1</sup>Department of Physiology, ²First Department of Internal Medicine and ³Department of Pharmacology, Hiroshima University, Faculty of Medicine, Minami-ku, Hiroshima 734-8551, Japan
*Corresponding author. FAX: +81-82-257-5187
E-mail: ytera@mcai.med.hiroshima-u.ac.jp

Abstract: We investigated whether a compensatory vasoconstrictor action would be induced by a hypotensive intervention in the hindquarter vascular region of conscious spontaneously hypertensive rats (SHRs). Mean arterial pressure and hindquarter blood flow were recorded. After hemorrhage (withdrawing blood, 0.3 ml/100 g body weight), hindquarter resistance (HQR) was increased significantly. The decrease in HQR induced by the administration of a ganglionic blocker (C6; 25 mg/kg, i.v.) was significantly greater in SHRs with hemorrhage than in those without hemorrhage. The present results suggest that a detectable hindquarter compensator tone occurs due to hemorrhage in SHRs, although an abnormal substantial vasoconstrictor tone already exists in the hindquarters.

Keywords: Hemorrhage, Hindquarter compensator, Spontaneously hypertensive rat