Physiologic and structural indices of vascular function in paraplegics.

In an effort to determine whether chronic physical forearm activity would increase both structural and physiologic indices of peripheral forearm vasodilation, we studied a group (N = 7) of individuals chronically performing high levels of arm work, young wheelchair-confined paraplegics, and compared them with ten young, able bodied control subjects. The index of vasodilator capacity was the flow response following the release of 10 min of arterial occlusion, the peak reactive hyperemic blood flow response (RHBF). The index of a structural effect of training on the vasculature was the brachial artery diameter (cm) derived by simultaneous measurement of velocity and forearm blood flow (area = flow.forearm volume.velocity-1). Vascular function differed significantly between the groups, with a greater RHBF (paraplegics, 53.8 +/- 3.7; controls, 38.2 +/- 1.5 ml.min-1.100 ml-1; P less than 0.05) and a larger brachial artery diameter at rest (paraplegics, 0.4 +/- 0.01 vs controls, 0.3 +/- 0.02 cm; P less than 0.05) in the paraplegics. We conclude that chronic upper extremity activity leads to an enhanced capability to vasodilate resistance vessels acutely and to a structural dilation of large conductance vessels.