This Article Full Text Full Text (PDF) All Versions of this Article: 106/5/620    most recent 01.CIR.0000023555.38685.5Bv1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sakata, K. Articles by Saruta, T. Search for Related Content PubMed PubMed Citation Articles by Sakata, K. Articles by Saruta, T. Related Collections Hypertension - basic studies Autonomic, reflex, and neurohumoral control of circulation

(Circulation. 2002;106:620.)
© 2002 American Heart Association, Inc.

Basic Science Reports

Potentiated Sympathetic Nervous and Renin-Angiotensin Systems Reduce Nonlinear Correlation Between Sympathetic Activity and Blood Pressure in Conscious Spontaneously Hypertensive Rats

Katsufumi Sakata, MD; Hiroo Kumagai, MD; Motohisa Osaka, MD; Toshiko Onami, MD; Tomokazu Matsuura, MD; Masaki Imai, MD; Takao Saruta, MD

From the Department of Internal Medicine, Keio University School of Medicine, Tokyo (K.S., H.K., T.O., T.M., M.I., T.S.), and the Institute of Gerontology, Nippon Medical School, Kawasaki (M.O.), Japan.

Correspondence to Hiroo Kumagai, MD, Department of Internal Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. E-mail hkumagai{at}sc.itc.keio.ac.jp

Background— Patients with a reduced nonlinear component of heart rate regulation have a poorer outcome.

Methods and Results— We investigated whether a nonlinear correlation between renal sympathetic nerve activity (RSNA) and blood pressure or renal blood flow is reduced in conscious, spontaneously hypertensive rats (SHR) by comparing them with normotensive Wistar-Kyoto rats (WKY). We also determined the linearity and nonlinearity of the correlation in SHR who were given an angiotensin II receptor blocker, candesartan, orally for 2 weeks. The RSNA value was higher in SHR than in WKY, and coherence peaks of transfer function were found at 0.05 and 0.80 Hz (ie, below respiratory- and cardiac-related fluctuations). The coherence (linearity) of the transfer function was significantly higher and gain was smaller in SHR than in WKY. Because mutual information values (linear and nonlinear correlation) were similar in both strains, we found the nonlinear correlation to be lower in SHR than in WKY. Time delay values calculated by the mutual information method demonstrated that RSNA preceded blood pressure and renal blood flow by 0.5 to 1.0 s. In SHR given candesartan, the RSNA value was lower, and the linearity was lower and nonlinearity higher than SHR given vehicle.

Conclusions— Linear correlation between RSNA and blood pressure or renal blood flow was higher in SHR than in WKY, whereas the nonlinear correlation was lower. Oral treatment with candesartan increased the nonlinearity and reduced the linearity in SHR. Increased RSNA and the renin-angiotensin system may be responsible for the lower nonlinearity and higher linearity in hypertension.

Key Words: hypertension • nervous system, sympathetic • angiotensin

This article has been cited by other articles:

				M. Ieda, H. Kanazawa, Y. Ieda, K. Kimura, K. Matsumura, Y. Tomita, T. Yagi, T. Onizuka, K. Shimoji, S. Ogawa, et al. Nerve Growth Factor Is Critical for Cardiac Sensory Innervation and Rescues Neuropathy in Diabetic Hearts Circulation, November 28, 2006; 114(22): 2351 - 2363. [Abstract] [Full Text] [PDF]

				T. Matsuura, H. Kumagai, H. Onimaru, A. Kawai, K. Iigaya, T. Onami, K. Sakata, N. Oshima, T. Sugaya, and T. Saruta Electrophysiological Properties of Rostral Ventrolateral Medulla Neurons in Angiotensin II 1a Receptor Knockout Mice Hypertension, August 1, 2005; 46(2): 349 - 354. [Abstract] [Full Text] [PDF]

				T. Matsuura, H. Kumagai, A. Kawai, H. Onimaru, M. Imai, N. Oshima, K. Sakata, and T. Saruta Rostral Ventrolateral Medulla Neurons of Neonatal Wistar-Kyoto and Spontaneously Hypertensive Rats Hypertension, October 1, 2002; 40(4): 560 - 565. [Abstract] [Full Text] [PDF]