Acute exercise attenuates cardiac autonomic regulation in hypertensive rats.
*Physical Exertion; Adrenergic Agents/pharmacology; Animals; Autonomic Nervous System/*physiopathology; Blood Pressure/drug effects; Cholinergic Agents/pharmacology; Heart Conduction System/*physiopathology; Heart Rate/drug effects; Hypertension/*physiopathology; Inbred SHR; Male; Nitroglycerin/pharmacology; Parasympathetic Nervous System/physiopathology; Phenylephrine/pharmacology; Rats; Sympathetic Nervous System/physiopathology; Time Factors
Dynamic exercise may be used as a safe, therapeutic approach to reduce sympathetic nerve activity at rest and thus may be beneficial for individuals with hypertension. Therefore, we tested the hypothesis that a single bout of mild to moderate dynamic exercise would decrease cardiac sympathetic tonus at rest. We designed two experimental protocols to test this hypothesis in male spontaneously hypertensive rats. In protocol 1 (n = 6) cardiac sympathetic tonus and parasympathetic tonus were determined before and after a single bout of dynamic exercise. We developed protocol 2 (n = 5) to determine the component of the autonomic nervous system responsible for the postexercise reduction in heart rate. Rats were instrumented with catheters inserted into the descending aorta for measurements of arterial pressure, mean arterial pressure, and heart rate and into the jugular vein for infusion of drugs. A single bout of mild to moderate dynamic treadmill exercise (12 m/min, 10% grade for 42 +/- 1 minutes, representing approximately 74% to 79% of maximal heart rate) resulted in a postexercise reduction in mean arterial pressure (163 +/- 7 to 149 +/- 5 mm Hg; P \textless .05). Associated with the postexercise hypotension was a reduction in sympathetic and parasympathetic tonus (47 +/- 12% and 71 +/- 12%, respectively). The reduction in heart rate during the early recovery phase was due to a withdrawal of sympathetic tonus, because beta 1-adrenergic receptor blockade significantly enhanced the postexercise reduction in heart rate, and muscarinic-cholinergic receptor blockade did not affect the postexercise decrease in heart rate until 20 minutes after exercise.
Chen Y; Chandler M P; DiCarlo S E
Hypertension (Dallas, Tex. : 1979)
1995
1995-10
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1161/01.hyp.26.4.676" target="_blank" rel="noreferrer noopener">10.1161/01.hyp.26.4.676</a>
Daily exercise and gender influence postexercise cardiac autonomic responses in hypertensive rats.
*Physical Conditioning; Animal; Animals; Atropine Derivatives/pharmacology; Autonomic Nervous System/drug effects/*physiopathology; Exercise Test; Female; Heart Rate/*drug effects; Heart/*innervation; Hypertension/genetics/*physiopathology; Inbred SHR; Male; Metoprolol/pharmacology; Nitroglycerin/pharmacology; Phenylephrine/pharmacology; Rats; Running; Sex Characteristics; Sympathetic Nervous System/drug effects/*physiopathology; Weight Loss
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 \textless 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 \textless 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 Y; Chandler M P; DiCarlo S E
The American journal of physiology
1997
1997-03
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/ajpheart.1997.272.3.H1412" target="_blank" rel="noreferrer noopener">10.1152/ajpheart.1997.272.3.H1412</a>