Femoral Artery Occlusion Increases Muscle Pressor Reflex and Expression of Hypoxia-Inducible Factor-1α in Sensory Neurons.

Hypoxia inducible factor-1 (HIF-1) has an important contribution to pathophysiological changes of homeostasis under conditions of oxygen deprivation as well as ischemia. We examined the effects of femoral artery occlusion on HIF-1α expression in sensory dorsal root ganglion (DRG) neurons of rats. Also, we examined cardiovascular responses to static muscle contraction following femoral occlusion. We hypothesized that hindlimb vascular insufficiency increases the levels of sensory nerves' HIF-1α and augments autonomic responses induced by activation of muscle afferent nerves. In addition, we examined if the reflex cardiovascular responses were altered as HIF-1α was increased in the DRG neurons. Our data show that HIF-1α was significantly increased in the lumbar DRG neurons 6, 24 and 72 hours after femoral artery ligation as compared with sham control. Administration of dimethyloxalylglycine (DMOG), a stabilizer of HIF-α, significantly increased HIF-1α in the lumbar DRG neurons. Furthermore, femoral occlusion enhanced the reflex pressor response to muscle contraction; however, the response was not altered by injection of DMOG. Overall, our results indicate that 1) femoral artery occlusion increases HIF-1α levels of in DRG neurons and contraction-induced pressor response; and 2) an increase in HIF-1α of DRG neurons per se may not alter the muscle pressor reflex.