Acute limb congestion (LC) increases the ventilatory response to static handgrip in normal volunteers

Previously we showed that LC augments the muscle sympathetic nerve response to handgrip by increasing muscle mechanoreceptor activity. In the present report we examined if LC during fatiguing handgrip at 35% maximal voluntary contraction would increase minute ventilation ( V, 1/min). LC was induced by 5 min of arm cuff occlusion at 90 mmHg before handgrip (n=19). Forearm exercise increased V from 9.3±.32 to 11.3±.39 (p<.05). During post handgrip circulatory arrest (PHG-CA) which selectively engages muscle metaboreceptors, V was still greater than baseline (p<.05). LC at rest had no effect on V. However, peak V coupled with LC was greater than V during handgrip alone (without LC 11.3±.4, with LC 12.3±.6 1/min; p<.05). Of note, the effects of LC weren't seen during PHG-CA (without LC 10.6±.5, with LC 11.2±.5 l/min; NS). Thus, LC increases V during handgrip. This effect wasn't due to a LC induced metaboreceptor activation since V during PHG-CA with and without limb congestion were not statistically different. We speculate that chroniccongestion and peripheral edema as would be seen in congestive heart failure (CHF) sensitizes mechanically sensitive muscle afférents increasing minute ventilation during exercise. Whether this contributes to the dyspnea of CHF remains to be explored.