Daily exercise attenuates the sympathetic nerve response to exercise by enhancing cardiac afferents.

Title

Daily exercise attenuates the sympathetic nerve response to exercise by enhancing cardiac afferents.

Creator

DiCarlo S E; Stahl L K; Bishop V S

Publisher

The American journal of physiology

Date

1997
1997-09

Description

"Central command" may initiate the sympathoexcitatory responses at the onset of exercise by shifting the operating point of the arterial baroreflex toward higher pressures. Daily exercise (DE) attenuates the sympathoexcitatory responses to submaximal exercise. This DE-induced adaptation may be due, in part, to an enhanced inhibitory influence of cardiac afferents. This is suggested because cardiac afferents exert a tonic inhibitory influence on the arterial baroreflex which is enhanced by DE. Therefore, the influence of cardiac afferents on the regulation of renal sympathetic nerve activity (RSNA) during exercise was examined in a group of sedentary and age-matched DE rabbits. The rabbits were instrumented with a Silastic catheter inserted into the pericardial sac, electrodes around the renal sympathetic nerves, and catheters in the femoral artery and vein. In the sedentary rabbits, treadmill exercise (12 m/min, 20% grade) significantly increased mean arterial pressure (delta 18 +/- 3 mmHg), heart rate (delta 36 +/- 3 beats/min), and RSNA (delta 295 +/- 23%). More importantly, cardiac afferent blockade (2% intrapericardial procainamide) did not significantly alter the RSNA response to exercise in the sedentary rabbits. DE did not alter the mean arterial pressure (delta 15 +/- 1 mmHg) or heart rate (delta 55 +/- 8 beats/min) response to exercise; however, RSNA (delta 252 +/- 9%) was significantly reduced. In contrast to the sedentary rabbits, cardiac afferent blockade in the DE rabbits significantly increased the RSNA response to exercise (delta 417 +/- 30%). These results suggest that DE attenuates the RSNA response to dynamic exercise due, in part, to an enhanced inhibitory influence of cardiac afferents.

Subject

Afferent Pathways; Animal/*physiology; Animals; Baroreflex; Blood Pressure; Femoral Artery/physiology; Femoral Vein/physiology; Heart Rate; Heart/innervation/*physiology; Kidney/innervation; Physical Conditioning; Rabbits; Sympathetic Nervous System/*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

H1606–1610

Issue

3

Volume

273

Citation

DiCarlo S E; Stahl L K; Bishop V S, “Daily exercise attenuates the sympathetic nerve response to exercise by enhancing cardiac afferents.,” NEOMED Bibliography Database, accessed July 28, 2021, https://neomed.omeka.net/items/show/4620.

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