title: Daily exercise and gender influence postexercise cardiac autonomic responses in hypertensive rats.
abstract: 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.
authors.affiliation: Department of Physiology, Northeastern Ohio Universities College of Medicine, Rootstown 44272, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
authors.forename: M P
authors.initials: MP
authors.lastname: Chandler
authors.forename: S E
authors.initials: SE
authors.lastname: DiCarlo
mesh_terms: 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
chemical_list: D001286:Atropine Derivatives; D010656:Phenylephrine; C006649:methylatropine; D005996:Nitroglycerin; D008790:Metoprolol