Endothelium-dependent regulation of cutaneous microcirculation in patients with systemic scleroderma

The microinjection method used for the first time in this study makes it possible to measure in vivo the endothelium-dependent vasomotion in the nailfold capillaries of systemic scleroderma patients. Aceylcholine (blood concentration of 10(-5) M) and sodium nitroprusside (blood concentration of 1.6 microg per kg per min) were used as test substances to examine capillary vasomotion. Defined quantities of medication in the range of microliters were administered as a bolus using the Panomat V-3 medicine pump. The boluses were injected into the capillaries at the capillary loop in 10 scleroderma patients and 10 randomized healthy volunteers. Blood flow velocity and the diameter of the skin capillaries at the venous loop were measured and tested for correlation with the effects of injections of test substances. The intracapillary administration of sodium nitroprusside brought about a significant decrease in capillary blood flow velocity and a significant increase in vascular diameter in comparison with baseline values, both in systemic scleroderma patients (p<0.005 and p<0.0001) and in the healthy volunteers (p<0.001 and p<0.0001). The intracapillary administration of acetylcholine led to a significant decrease in blood flow velocity (p<0.001) and increase in vascular diameter (p<0.0001) only in the healthy volunteers. In systemic sclerosis patients capillary diameter and blood flow velocity were unaffected. In two systemic scleroderma patients this procedure was repeated in identical fashion at the end of a 1 wk infusion therapy cycle with prostacyclin. The infusion therapy led to a normalization of endothelium-dependent vasomotion in the two scleroderma patients. The microinjection technique used in this study for the first time made it possible to establish in vivo that endothelium-dependent vasomotion is disturbed in systemic scleroderma patients.