EFFECT OF LOCALIZED CUTANEOUS STIMULATION ON CIRCULATION IN DUODENAL ARTERIOLES AND CAPILLARY BEDS

Abstract

Warm (45[degree]C) or cold (ice water) cutaneous stimulation was applied to the dorsum of the thorax of white rats. While the stimulus was being applied the duodenum was frozen in a mixture of dry ice and acetone (-70[degree] to -78[degree]C) and a small piece removed for fixation by freezing and drying. Paraffine sections were prepd. and studied under the microscope. During cutaneous application of warmth the arterioles in the sub-serosa and submucosa of the duodenum were dilated, and the capillary beds in the villi were engorged with blood. During application of cold the corresponding arterioles were constricted, and the capillary beds were ischemic. Tonic changes seemed greater in the arterioles of the subserosa, but blood flow here was rapid both during vasoconstriction and vasodilatation. Vasomotor activity in the arterioles of the submucosa seemed more significant in the regulation of blood flow since blood flowed rapidly only during vasodilatation and was slowed during vasoconstriction. Vasoconstriction in arterioles of the submucosa, furthermore, was a rigidly controlled response to reflex nerve stimulation. Vasodilator reflexes were more loosely regulated.