TY - JOUR
T1 - Reflex effects on circulation and respiration from contracting skeletal muscle
AU - Mitchell, J. H.
AU - Reardon, W. C.
AU - McCloskey, D. I.
PY - 1977
Y1 - 1977
N2 - Isometric exercise induced by ventral root stimulation in the anesthetized cat caused heart rate (HR) to increase from 199±6 beats/min to 206±6 (P<0.001); mean arterial pressure (MAP) from 99±5.3 mmHg to 112±5.8 (P<0.001); and left ventricular dp/dt at developed pressure of 25 mmHg from 3,960±204 mmHg/s to 4,380±220 (P<0.001), while end-diastolic pressure remained unchanged. Respiratory volume (RV) increased from 755±71 ml/min to 1,160±123 (P<0.001). These changes were abolished by cutting the dorsal roots receiving afferents from the exercising muscle. Beta-adrenergic blockade with propranolol (1 mg/kg) abolished the changes in heart rate and contractile state; however, changes in MAP and RV still occurred. Induced isometric exercise causes a small rise in HR with a more marked increase in MAP, the contractile state of the left ventricle and RV. In this preparation the cardiovascular and respiratory changes reflexly originate from contracting skeletal muscle as proven by section of the corresponding dorsal roots, and the cardiovascular changes are mediated in part by activation of beta-adrenergic receptors in the heart.
AB - Isometric exercise induced by ventral root stimulation in the anesthetized cat caused heart rate (HR) to increase from 199±6 beats/min to 206±6 (P<0.001); mean arterial pressure (MAP) from 99±5.3 mmHg to 112±5.8 (P<0.001); and left ventricular dp/dt at developed pressure of 25 mmHg from 3,960±204 mmHg/s to 4,380±220 (P<0.001), while end-diastolic pressure remained unchanged. Respiratory volume (RV) increased from 755±71 ml/min to 1,160±123 (P<0.001). These changes were abolished by cutting the dorsal roots receiving afferents from the exercising muscle. Beta-adrenergic blockade with propranolol (1 mg/kg) abolished the changes in heart rate and contractile state; however, changes in MAP and RV still occurred. Induced isometric exercise causes a small rise in HR with a more marked increase in MAP, the contractile state of the left ventricle and RV. In this preparation the cardiovascular and respiratory changes reflexly originate from contracting skeletal muscle as proven by section of the corresponding dorsal roots, and the cardiovascular changes are mediated in part by activation of beta-adrenergic receptors in the heart.
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U2 - 10.1152/ajpheart.1977.233.3.h374
DO - 10.1152/ajpheart.1977.233.3.h374
M3 - Article
C2 - 910926
AN - SCOPUS:0017726366
SN - 0363-6135
VL - 2
SP - 374
EP - 378
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 3
ER -