Exercise training improves aortic depressor nerve sensitivity in rats with ischemia-induced heart failure

• Published in: American journal of physiology. Heart and circulatory physiology 2006-12, Vol.291 (6), p.H2801-H2806
• Main Authors: Rondon, Eduardo, Brasileiro-Santos, Maria S, Moreira, Edson D, Rondon, Maria U. P. B, Mattos, Katt C, Coelho, Marcele A, Silva, Gustavo J. J, Brum, Patricia C, Fiorino, Patricia, Irigoyen, Maria C, Krieger, Eduardo M, Middlekauff, Holly R, Negrao, Carlos E
• Format: Article
• Language: English
• Subjects: Algorithms; Anemia; Animals; Aorta - innervation; Aorta - physiology; Baroreflex - physiology; Blood pressure; Blood Pressure - physiology; Cardiac Output, Low - etiology; Cardiac Output, Low - physiopathology; Exercise; Heart failure; Heart Rate - physiology; Kidney - innervation; Kidney - physiology; Male; Myocardial Ischemia - complications; Myocardial Ischemia - physiopathology; Physical Conditioning, Animal - physiology; Pressoreceptors - physiology; Rats; Rats, Wistar; Rodents; Sympathetic Nervous System - physiology; Veins & arteries
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.01352.2005

1 Heart Institute (Instituto do Coração), Medical School, and 2 School of Physical Education and Sports, University of São Paulo, São Paulo, Brazil; and 3 Medical School, Department of Cardiology, University of California, Los Angeles, California Submitted 21 December 2005 ; accepted in final form 16 June 2006 Exercise training improves arterial baroreflex control in heart failure (HF) rabbits. However, the mechanisms involved in the amelioration of baroreflex control are unknown. We tested the hypothesis that exercise training would increase the afferent aortic depressor nerve activity (AODN) sensitivity in ischemic-induced HF rats. Twenty ischemic-induced HF rats were divided into trained ( n = 11) and untrained ( n = 9) groups. Nine normal control rats were also studied. Power spectral analysis of pulse interval, systolic blood pressure, renal sympathetic nerve activity (RSNA), and AODN were analyzed by means of autoregressive parametric spectral and cross-spectral algorithms. Spontaneous baroreflex sensitivity of heart rate (HR) and RSNA were analyzed during spontaneous variation of systolic blood pressure. Left ventricular end-diastolic pressure was higher in HF rats compared with that in the normal control group ( P = 0.0001). Trained HF rats had a peak oxygen uptake higher than untrained rats and similar to normal controls ( P = 0.01). Trained HF rats had lower low-frequency [1.8 ± 0.2 vs. 14.6 ± 3 normalized units (nu), P = 0.0003] and higher high-frequency (97.9 ± 0.2 vs. 85.0 ± 3 nu, P = 0.0005) components of pulse interval than untrained rats. Trained HF rats had higher spontaneous baroreceptor sensitivity of HR (1.19 ± 0.2 vs. 0.51 ± 0.1 ms/mmHg, P = 0.003) and RSNA [2.69 ± 0.4 vs. 1.29 ± 0.3 arbitrary units (au)/mmHg, P = 0.04] than untrained rats. In HF rats, exercise training increased spontaneous AODN sensitivity toward normal levels (trained HF rats, 1,791 ± 215; untrained HF rats, 1,150 ± 158; and normal control rats, 2,064 ± 327 au/mmHg, P = 0.05). In conclusion, exercise training improves AODN sensitivity in HF rats. baroreflex control; autonomic nervous system Address for reprint requests and other correspondence: C. E. Negrão, Instituto do Coração, Unidade de Reabilitação Cardiovascular e Fisiologia do Exercício, Av. Dr. Enéas de Carvalho Aguiar, 44–Cerqueira César, São Paulo–SP, CEP 05403-000 Brazil (e-mail: cndnegrao{at}incor.usp.br )