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Responses of thin fiber muscle afferents to contraction are greater in ligated than in freely perfused rats
Author(s) -
Stone Audrey,
Copp Steven,
Kaufman Marc
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.1054.7
Subject(s) - contraction (grammar) , reflex , nerve conduction velocity , chemistry , endocrinology , hindlimb , medicine , muscle contraction , anatomy , electrophysiology
Previous evidence has shown that ligating the femoral artery for 72 hours resulted in an exaggerated exercise pressor reflex. Nevertheless, electrophysiological evidence concerning the afferent arm of the reflex that is supportive of this exaggeration is lacking. Consequently, in decerebrated rats whose femoral arteries were either freely perfused or ligated for 72 hours, we compared the responses of thin fiber (i.e., group III & IV) muscle afferents to static contraction of the hindlimb muscles. We found that contraction in freely perfused rats increased thin fiber afferent activity (mean conduction velocity: 3.8±0.5 m/s) from 0.3±0.1 imp/s to 0.8±0.2 imp/s (n=26; p<0.05). In contrast, in ligated rats contraction increased afferent activity (mean conduction velocity: 3.4±0.6 m/s) from 0.4±0.1 imp/s to 1.4±0.1 imp/s (n=22; p<0.05). The contraction induced increase in thin fiber afferent activity was significantly greater in ligated rats than that in freely perfused rats (p<0.05). Stretch stimulated 12 of 17 group III afferents in freely perfused and 7 of 12 group III afferents in ligated rats. Nevertheless, each of these 29 group III afferents responded to contraction. In contrast, stretch did not stimulate any group IV afferents in either freely perfused or ligated rats. We conclude that static contraction stimulates thin fiber muscle afferents to a greater extent in ligated rats than that in freely perfused rats. This finding provides an electrophysiological basis for the exaggeration of the exercise pressor reflex by chronic obstruction of femoral artery blood flow. In addition, this finding may provide a basis for the exaggerated exercise pressor reflex seen in peripheral artery disease. Funding: NIH AR‐059397, HL‐096570