Acute exercise and gender alter cardiac autonomic tonus differently in hypertensive and normotensive rats.

Acute exercise and gender alter cardiac autonomic tonus differently in hypertensive and normotensive rats.

Chandler M P; DiCarlo S E

The American journal of physiology

1998

1998-02

Arterial pressure (AP), heart rate (HR), cardiac sympathetic tonus (ST), and parasympathetic tonus (PT) were determined in spontaneously hypertensive rats (SHR, 8 male and 8 female) and Wistar-Kyoto normotensive rats (WKY, 8 male and 12 female) before and after acute exercise. Before exercise, hypertensive rats (regardless of gender) had an increased ST (+15 beats/min), increased resting HR (+12 beats/min), and decreased PT (-11 beats/min). Similarly, female rats (regardless of strain) also had an increased ST (+15 beats/min), increased resting HR (+39 beats/min), and decreased PT (-14 beats/min). Hypertensive rats had a significant reduction in AP (-17 +/- 3 mmHg), ST (-26 beats/min), PT (-7 beats/min), and HR (-14 beats/min) after exercise. In contrast, AP was not reduced in normotensive rats and ST (+18 beats/min) and HR (+42 beats/min) were increased in female normotensive rats after exercise. However, male normotensive rats had a postexercise reduction in ST (-14 beats/min) and HR (-19 beats/min). In summary, AP, ST, and resting HR were higher whereas PT was lower in hypertensive vs. normotensive rats. Furthermore, females had a higher resting HR, intrinsic HR, and ST and lower PT than male rats. These data demonstrate that gender and the resting level of AP influence cardiac autonomic regulation.

*Sex Characteristics; Adrenergic alpha-Antagonists/pharmacology; Animals; Autonomic Nervous System/drug effects/*physiopathology; Blood Pressure; Female; Heart Rate/physiology; Heart/*innervation; Hypertension/*physiopathology; Inbred SHR; Inbred WKY; Male; Metoprolol/pharmacology; N-Methylscopolamine/pharmacology; Parasympathetic Nervous System/drug effects/physiopathology; Parasympatholytics/pharmacology; Physical Exertion/*physiology; Rats; Sympathetic Nervous System/drug effects/physiopathology

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R510–516

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