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Heart rate and arterial blood pressure at the onset of static exercise in man with complete neural blockade.
Author(s) -
Friedman D B,
Jensen F B,
Mitchell J H,
Secher N H
Publication year - 1990
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1990.sp018038
Subject(s) - heart rate , blood pressure , medicine , blockade , cold pressor test , anesthesia , reflex , cardiology , receptor
1. We tested the ‘muscle‐heart reflex’ hypothesis for the immediate increases in heart rate and blood pressure at the onset of static exercise in man by performing complete blockade of afferent nerves from the working muscles. Brief (5 s) maximal static hand‐grip contractions were performed without performing a Valsalva‐like manoeuvre and with no increase in central venous pressure both before and after combined axillary and radial blockade with lidocaine. Muscle strength was reduced to near zero. The effectiveness of the afferent neural blockade was evaluated by recording the heart rate and blood pressure responses and rating the perceived pain during a cold pressor test of the blocked and contralateral unblocked hand. 2. The cold pressor test increased blood pressure but had no effect on heart rate. Afferent neural blockade eliminated the increase in blood pressure and the perceived pain associated with the cold pressor test. Maximal hand‐grip contractions resulted in immediate and similar increases in heart rate and blood pressure before and after afferent neural blockade of the arm. 3. The results of this study suggest that the immediate increases in heart rate and blood pressure at the onset of static exercise in man occur when the ‘muscle‐heart reflex’ is inoperable.