The effect of ovariectomy on cardiac autonomic control in rats submitted to aerobic physical training.
We have investigated the ovariectomy effects on the cardiovascular autonomic adaptations induced by aerobic physical training and the role played by nitric oxide (NO). Female Wistar rats (n=70) were divided into five groups: Sedentary Sham (SS); Trained Sham (TS); Trained Hypertensive Sham treated with N(G)-nitro-L-arginine methyl ester (L-NAME) (THS); Trained Ovariectomized (TO); and Trained Hypertensive Ovariectomized treated with L-NAME (THO). Trained groups were submitted to a physical training during 10 weeks. The cardiovascular autonomic control was investigated in all groups using different approaches: 1) pharmacological evaluation of autonomic tonus with methylatropine and propranolol; 2) analysis of heart rate (HR) and systolic arterial pressure (AP) variability; 3) spontaneous baroreflex sensitivity (BRS) evaluation. Hypertension was observed in THS and THO groups. Pharmacological analysis showed that TS group had increased predominance of autonomic vagal tonus compared to SS group. HR and intrinsic HR were found to be reduced in all trained animals. TS group, compared to other groups, showed a reduction in LF oscillations (LF=0.2-0.75 Hz) of pulse interval in both absolute and normalized units as well as an increase in HF oscillations (HF=0.75-2.50 Hz) in normalized unit. BRS analysis showed that alpha-index was different between all groups. TS group presented the greatest value, followed by the TO, SS, THO and THS groups. Ovariectomy has negative effects on cardiac autonomic modulation in trained rats, which is characterized by an increase in the sympathetic autonomic modulation. These negative effects suggest NO deficiency. In contrast, the ovariectomy seems to have no effect on AP variability.
Tezini
Geisa C S V
GC
Department of Biomechanics, Medicine and Rehabilitation of School of Medicine of Ribeirão Preto, University of São Paulo, 14049-900, Ribeirão Preto, SP, Brazil.
Silveira
Larissa C R
LC
Maida
Karina D
KD
Blanco
João Henrique D
JH
Souza
Hugo C D
HC
D000284:Administration, Oral; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001286:Atropine Derivatives / Q000008:administration & dosage / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002319:Cardiovascular System / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology; D007275:Injections, Intravenous; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology; D010052:Ovariectomy; D010276:Parasympatholytics / Q000008:administration & dosage / Q000494:pharmacology; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011433:Propranolol / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D000319:Adrenergic beta-Antagonists; D001286:Atropine Derivatives; D010276:Parasympatholytics; D009569:Nitric Oxide; C006649:methylatropine; D011433:Propranolol; D019331:NG-Nitroarginine Methyl Ester