INFLUENCE OF HYPERTENSION ON TETRAHYDROPAPAVEROLINE-INDUCED VASORELAXATION IN RAT THORACIC AORTA

Abstract

Tetrahydropapaveroline (THP), a condensation product of ethanol-derived acetaldehyde, has been shown to elicit a vasorelaxant response in rat thoracic aorta. This study examined the influence of hypertension on the THP-induced vasorelaxant responsiveness. Ring segments of thoracic aorta were isolated from Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) and isometric tension development was measured with a force transducer. In aorta, with or without intact endothelium, the contractile responses to potassium chloride (0–120 mM) were comparable between the WKY and the SHR groups. Hypertension did not affect the vasoconstrictive response to norepinephrine (0–10 µM) in vessels with intact endothelium, whereas it attenuated the norepinephrine-induced response in vessels without endothelium. THP (0.1–100 µM) elicited endothelium-intact as well as -denuded vasorelaxation in aorta from both WKY and SHR groups. Interestingly, the THP-induced endothelium-dependent vasorelaxation was significantly enhanced, whereas the THP-induced endothelium-independent vasorelaxation was not affected by hypertension. These data indicate that the THP-induced endothelium-dependent vasorelaxant response is altered by the hypertensive state.

ACKNOWLEDGMENTS

The authors acknowledge Loren E. Wold and Bonnie H. Ren for their assistance in preparing this manuscript. This work was supported by grants from National Institute of Health MH47181, GM08167 (RAB).