VENOUS CONGESTION AND RHYTHMIC HANDGRIP

We have shown that venous congestion augments the muscle sympathetic nerve activity response to static handgrip. This augmented activity during static handgrip was not followed by greater activity during post handgrip circulatory arrest a maneuver which traps metabolites and isolates the effects of metabolic sensitive afferents. Therefore, another mechanism besides metaboreceptors must account for the greater muscle sympathetic nerve activity. Venous congestion produced by occluding venous outflow, raises venous and interstitial pressures and stimulates conditions found in congestive heart failure. We will examine rhythmic handgrip and venous congestion because rhythmic handgrip does not generally cause metaboreceptor activation, but rather any muscle sympathetic nerve activity response will be due to another stimulus such as mechanoreceptors. We will prevent flow limitation during rhythmic handgrip by releasing venous occlusion at the start of the exercise.