This Article Full Text 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 Gava, N. S. Articles by Krieger, E. M. Search for Related Content PubMed PubMed Citation Articles by Gava, N. S. Articles by Krieger, E. M.

(Hypertension. 1995;26:1129-1133.)
© 1995 American Heart Association, Inc.

Articles

Low-Intensity Exercise Training Attenuates Cardiac ß-Adrenergic Tone During Exercise in Spontaneously Hypertensive Rats

Nilo Sérgio Gava; Acácio Salvador Véras-Silva; Carlos Eduardo Negrão; Eduardo Moacyr Krieger

From the Exercise Physiology Laboratory, Physical Education School (N.S.G., A.S.V.-S., C.E.N.), and the Hypertension Unit, Heart Institute, Faculty of Medicine (C.E.N., E.M.K.), University of São Paulo (Brazil).

Correspondence to Eduardo Moacyr Krieger, MD, PhD, Hypertension Unit, Heart Institute, Faculty of Medicine, University of São Paulo, Av Dr Enéas Carvalho de Aguiar, 44, São Paulo, Brazil, CEP O5403-000.

Abstract Acute and chronic exercise decrease peripheral sympathetic nerve activity, but the effect of exercise training of varying intensity on the sympathetic control of heart rate of spontaneously hypertensive rats has not yet been described. The effect of low and high intensities of exercise training on the vagal and sympathetic activities that control heart rate at rest and during dynamic exercise at 0.5, 0.8, and 1.0 mph for 4 minutes per stage was investigated in sedentary (SED, n=11), high-intensity (HT, n=12), and low-intensity exercise–trained (LT, n=13) spontaneously hypertensive rats. Exercise training was performed on a treadmill for 60 minutes, 5 days per week for 18 weeks, at 55% maximum oxygen consumption for the LT group and 85% for the HT group. Vagal and sympathetic activities were studied after administration of methylatropine (3 mg/kg) and propranolol (4 mg/kg), respectively. The LT group had a significantly lower heart rate (at 0.5, 0.8, 1.0 mph versus rest: 410±7, 426±7, 464±9, and 295±6 beats per minute [bpm], respectively) than the HT (440±6, 453±7, 474±5, and 315±4 bpm) and the SED (474±11, 500±11, 523±10, and 327±3 bpm) groups. Sympathetic effect (LT: 84±10, 88±12, 105±12, and 9±4; HT: 123±8, 125±7, 133±7, and 34±7; SED: 130±13, 143±12, 150±10, and 38±7 bpm) and sympathetic tonus (LT: 125±6, 121±5, 112±6, and 91±6; HT: 145±9, 136±6, 142±8, and 118±7; SED: 136±6, 129±6, 132±7, and 118±8 bpm) were significantly decreased by low-intensity exercise training. In conclusion, low- but not high-intensity exercise training causes resting bradycardia and attenuation of tachycardiac response during progressive dynamic exercise in spontaneously hypertensive rats. This effect can be attributed to a significantly decreased ß-adrenergic tone that controls heart rate.

Key Words: adrenergic ß-antagonists • blood pressure • bradycardia • exercise • heart rate • rats, inbred SHR

This article has been cited by other articles:

				N. P. L. Rolim, A. Medeiros, K. T. Rosa, K. C. Mattos, M. C. Irigoyen, E. M. Krieger, J. E. Krieger, C. E. Negrao, and P. C. Brum Exercise training improves the net balance of cardiac Ca2+ handling protein expression in heart failure Physiol Genomics, May 11, 2007; 29(3): 246 - 252. [Abstract] [Full Text] [PDF]

				E. Rondon, M. S. Brasileiro-Santos, E. D. Moreira, M. U. P. B. Rondon, K. C. Mattos, M. A. Coelho, G. J. J. Silva, P. C. Brum, P. Fiorino, M. C. Irigoyen, et al. Exercise training improves aortic depressor nerve sensitivity in rats with ischemia-induced heart failure Am J Physiol Heart Circ Physiol, December 1, 2006; 291(6): H2801 - H2806. [Abstract] [Full Text] [PDF]

				H. L. Lujan, S. L. Britton, L. G. Koch, and S. E. DiCarlo Reduced susceptibility to ventricular tachyarrhythmias in rats selectively bred for high aerobic capacity Am J Physiol Heart Circ Physiol, December 1, 2006; 291(6): H2933 - H2941. [Abstract] [Full Text] [PDF]

				R. M. Melo, E. Martinho Jr, and L. C. Michelini Training-Induced, Pressure-Lowering Effect in SHR: Wide Effects on Circulatory Profile of Exercised and Nonexercised Muscles Hypertension, October 1, 2003; 42(4): 851 - 857. [Abstract] [Full Text] [PDF]

				G. M. STORY, S. E. DICARLO, D. W. RODENBAUGH, D. E. DLUZEN, J. KUCERA, M. B. MARON, and J. M. WALRO Inactivation of one copy of the mouse neurotrophin-3 gene induces cardiac sympathetic deficits Physiol Genomics, April 27, 2000; 2(3): 129 - 136. [Abstract] [Full Text] [PDF]

				K. D. A. L. d'Avila, G. Gadonski, J. Fang, P. Dall'Ago, V. L. Albuquerque, L. R. d. A. Peixoto, T. G. Fernandes, and M. C. Irigoyen Exercise Reverses Peripheral Insulin Resistance in Trained L-NAME-Hypertensive Rats Hypertension, October 1, 1999; 34(4): 768 - 772. [Abstract] [Full Text] [PDF]

				M. P. Chandler and S. E. Dicarlo Acute exercise and gender alter cardiac autonomic tonus differently in hypertensive and normotensive rats Am J Physiol Regulatory Integrative Comp Physiol, February 1, 1998; 274(2): R510 - R516. [Abstract] [Full Text] [PDF]

				A. S. Veras-Silva, K. C. Mattos, N. S. Gava, P. C. Brum, C. E. Negrao, and E. M. Krieger Low-intensity exercise training decreases cardiac output and hypertension in spontaneously hypertensive rats Am J Physiol Heart Circ Physiol, December 1, 1997; 273(6): H2627 - H2631. [Abstract] [Full Text] [PDF]

				G. J. J. Silva, P. C. Brum, C. E. Negrao, and E. M. Krieger Acute and Chronic Effects of Exercise on Baroreflexes in Spontaneously Hypertensive Rats Hypertension, September 1, 1997; 30(3): 714 - 719. [Abstract] [Full Text]