Adaptation of resistance vessels to chronic local hypotension in the dog

Distensibility of the vascular bed in subcutaneous tissue in generalized scleroderma

Passive distensibility of resistance vessels in subcutaneous tissue of hand and leg was examined in 6 normals and 8 patients suffering from generalized scleroderma of the acrosclerosis type. Local paralysis of smooth muscle was obtained by injection of papaverine and increase in transmural pressure by lowering the limb. Blood flow was estimated by the local 133Xenon wash-out method. Distensibility of blood vessels in subcutaneous tissue in generalized scleroderma was not decreased to a significant degree, whereas, both in patients and normals, the blood vessels of the leg exhibited diminished distensibility compared to blood vessels of the hand. The findings suggest that the morphologic changes of vascular and extravascular tissue observed in sclerodermic skin do not affect distensibility of the vascular bed in subcutaneous tissue.

Effects of therapy on maximal walking time following femoral ligation in the rat

Maximal walking times at a constant rate of 10 m/min were compared in normal rats, normal rats that had been exercised daily for 6 weeks, and rats that had undergone bilateral femoral artery ligation followed by 6 weeks of either an oral vasodilator, absence of sympathetic impulses to the extremities, cold exposure, or daily exercise. Rats maintained on the vasodilator could walk no farther than untreated, ligated rats. Both chronic cold exposure and sympathectomy significantly increased maximal walking distances of ligated rats and daily exercise increased maximal walking distances 7-fold. Rats that had received 6 weeks of exercise training following femoral artery ligation could walk longer than normal untrained rats; therefore, the increased exercise tolerance could not be explained solely by the restoration of normal large artery conductance by enlargement of collaterals bypassing the femoral occlusion.