Neurological Disease and Autonomic Dysfunction: Femoral artery ligationincreases the responses of thin-fiber muscle afferents to contraction: Femoral artery ligation increases the responses of thin-fiber muscleafferents to contraction

摘要

Previous evidence has shown that ligating the femoral artery for 72 h resulted in an exaggerated exercise pressor reflex. To provide electrophysiological evidence for this finding, we examined in decerebrated rats whose femoral arteries were either freely perfused or ligated for 72 h the responses of thin-fiber (i.e., groups III and IV) afferents to static contraction of the hindlimb muscles. We found that contraction increased the combined activity of group III and IV afferents in both freely perfused (n = 29; baseline: 0.3 ± 0.1 imp/s, contraction: 0.8 ± 0.2 imp/s; P < 0.05) and ligated rats (n = 28; baseline: 0.4 ± 0.1 imp/s, contraction: 1.4 ± 0.1 imp/s; P < 0.05). Most importantly, the contraction-induced increase in afferent activity was greater in ligated rats than it was in freely perfused rats (P = 0.005). In addition, the responses of group III afferents to contraction in ligated rats (n = 15; baseline 0.3 ± 0.1 imp/s, contraction 1.5 ± 0.2 imp/s) were greater (P = 0.024) than the responses to contraction in freely perfused rats (n = 18; baseline 0.3 ± 0.1 imp/s, contraction 0.9 ± 0.2 imp/s). Likewise, the responses of group IV afferents to contraction inligated rats (n = 13; baseline 0.5 ± 0.1 imp/s, contraction1.3 ± 0.2 imp/s) were greater (P = 0.048) than the responsesof group IV afferents in freely perfused rats (n = 11; baseline 0.3± 0.1 imp/s, contraction 0.6 ± 0.2 imp/s). We conclude that both groupIII and IV afferents contribute to the exaggeration of the exercise pressor reflexinduced by femoral artery ligation.