Daily exercise and gender influence postexercise cardiac autonomic responses in hypertensive rats.
The influence of daily spontaneous running (DSR) and gender on postexercise cardiac autonomic responses was examined in spontaneously hypertensive rats. Rats were weaned at 4-5 wk of age and were randomly assigned to a sedentary (7 males and 6 females) or DSR (7 males and 8 females) group. After 8 weeks of DSR or sedentary control, rats were chronically instrumented with arterial and venous catheters. After 5 days of recovery, cardiac sympathetic (ST) and parasympathetic tonus (PT) were determined (by the response of heart rate to receptor antagonists) on alternate days under two experimental conditions: no exercise and postexercise. After a single bout of dynamic treadmill exercise (12 m/min, 10% grade for 40 min) ST was reduced (P < 0.05) (male sedentary: no exercise 45 +/- 4 vs. postexercise 28 +/- 3 beats/min; female sedentary: no exercise 69 +/- 10 vs. postexercise 37 +/- 7 beats/ min). PT was also altered after exercise (male sedentary: no exercise -31 +/- 4 vs. postexercise -11 +/- 2 beats/min; female sedentary: no exercise -5 +/- 4 vs. postexercise 7 +/- 4 beats/min). After DSR, ST was reduced (male sedentary 45 +/- 4 vs. DSR 22 +/- 3 beats/min; female sedentary 69 +/- 10 vs. DSR 36 +/- 4 beats/min) (P < 0.05). Finally, male rats had a lower ST and higher PT than female rats. These results demonstrate that 1) ST was reduced after a single bout of dynamic exercise; 2) ST was reduced after DSR; 3) the autonomic response to acute exercise was attenuated after DSR; and 4) there was a gender influence on the cardiac autonomic function.
Chen
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Department of Physiology, Northeastern Ohio Universities College of Medicine, Rootstown 44272, USA.
Chandler
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MP
DiCarlo
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SE
D000818:Animals; D001286:Atropine Derivatives / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D005080:Exercise Test; D005260:Female; D006321:Heart / Q000294:innervation*; D006339:Heart Rate / Q000187:drug effects*; D006973:Hypertension / Q000235:genetics / Q000503:physiopathology*; D008297:Male; D008790:Metoprolol / Q000494:pharmacology; D005996:Nitroglycerin / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D010805:Physical Conditioning, Animal; D051381:Rats; D011918:Rats, Inbred SHR; D012420:Running; D012727:Sex Characteristics; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D015431:Weight Loss
D001286:Atropine Derivatives; D010656:Phenylephrine; C006649:methylatropine; D005996:Nitroglycerin; D008790:Metoprolol