Modulation of Baroreflexes in HypertensiveRats

Korean Journal of Nephrology 2009;28(6):545-551.

Seok Choi, Ph.D.1, Jai Hun Kim, M.D.1, Jae Myung Sun, M.D.1, Hee Wook Whi, M.D.1 Su Jin Choi, M.D.1, Jae Yeoul Jun, M.D.1, Pyung Jin Yoon, Ph.D.1 Jong Hoon Chung, M.D.2, Hyun Il Kim, M.D.3 and Cheol Ho Yeum, Ph.D.1

Department of Physiology¹
Internal Medicine2 and Psychiatry³
College of Medicine Chosun University, Gwangju, Korea

원저 : Modulation of Baroreflexes in HypertensiveRats

Department of Physiology1, Internal Medicine2 and Psychiatry3, College of Medicine Chosun University, Gwangju, Korea

Abstract

Purpose:Baroreceptor reflex regulation has been shown to reset towards a higher blood pressure level. This study was designed to assess alterations of chronotropic baroreflexes in two-kidney, one clip (2K1C) and deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Methods:Arterial pressure and heart rate (HR) were monitored continuously during intravenous infusions of phenylephrine or sodium nitroprusside. Ensuing reflex HR responses during each drug infusion were determined in two ways: (a) at 10 s intervals (time analysis), and (b) with every 10 mmHg change in pressure (pressure analysis). Results:Both pressor and depressor responses produced by phenylephrine or sodium nitroprusside were comparable between normotensive and hypertensive rats. Both reflex tachycardia and bradycardia were attenuated in 2K1C hypertensive rats as compared with normotensive rats, whereas no significant differences were shown in DOCA-salt hypertensive rats. Conclusion:These results indicate that chronotropic baroreflexes are impaired in 2K1C hypertensive rats, but not in DOCA-salt hypertensive rats.

Key Words: Baroreflex, Blood pressure, Heart rate, Hypertension