Daily spontaneous running did not alter vagal afferent reactivity.

Title

Daily spontaneous running did not alter vagal afferent reactivity.

Creator

Scislo T J; DiCarlo S E; Collins H L

Publisher

The American journal of physiology

Date

1993
1993-11

Description

Exercise training alters the cardiopulmonary baroreflex regulation of the circulation; however, the mechanisms responsible are unknown. One possibility is an enhanced afferent response to cardiopulmonary stimulation. We therefore tested the hypothesis that daily spontaneous running (DSR) would enhance cardiopulmonary vagal afferent responses to mechanical (increase in left atrial pressure, LAP) and chemical (phenyl biguanide, PBG) stimulation. Reactivity of single-fiber cardiopulmonary vagal afferents was evaluated in 16 control and 12 DSR anesthetized Sprague-Dawley rats. Rats were weaned at 3 wk of age and randomly assigned to a control or DSR group. Eight to twelve weeks of DSR was associated with a 27% increase in heart weight-to-body weight ratio (3.27 +/- 0.08 vs. 2.56 +/- 0.05 g/kg, P \textless 0.001) and resting bradycardia (394 +/- 10 vs. 421 +/- 8 beats/min, P = 0.036). However, DSR did not alter the stimulus-response curves to increases in LAP (frequency of discharge vs. LAP) for either the high-frequency (maximum response, sedentary 59.6 +/- 3.2, DSR 60.1 +/- 5.0 spikes/s) or low-frequency (maximum response, sedentary 20.0 +/- 2.9 DSR 20.6 +/- 3.9 spikes/s) receptors. Dose-response curves to chemical stimulation (spikes/s vs. PBG dose) were also not altered by DSR. Thus DSR did not change vagal afferent reactivity to mechanical or chemical stimulation.

Subject

*Blood Pressure/drug effects; *Heart Rate/drug effects; *Physical Conditioning; Afferent Pathways/drug effects/*physiology; Analysis of Variance; Animal; Animals; Biguanides/pharmacology; Body Weight; Female; Heart/anatomy & histology/drug effects/*physiology; Hypoglycemic Agents/pharmacology; Organ Size; Rats; Sprague-Dawley; Time Factors; Vagus Nerve/drug effects/*physiology

Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

H1564–1570

Issue

5

Volume

265

Citation

Scislo T J; DiCarlo S E; Collins H L, “Daily spontaneous running did not alter vagal afferent reactivity.,” NEOMED Bibliography Database, accessed December 2, 2021, https://neomed.omeka.net/items/show/4613.

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