Effect of temperature on reactivity of isolated cutaneous veins of the dog.

VANHOUTTE, PAUL M., AND JOHN T. SHEPHERD. Effect qf temperature on reactivity of isolated cutaneous veins of the dog. Am. J. Physiol. 218(l): 187-190. 1970.-Excised segments of dogs’ saphenous veins were perfused, with autologous blood or Krebs-Ringer solution, at constant flow. Changes in driving pressure were used to measure venomotor responses. The reactivity of the veins to electric stimulation and various vasoactive agents was tested at 37 C, and the effects of changes in temperature (25-43 C) were investigated. When the veins were constricted by electric stimulation, norepinephrine, Shydroxytryptamine, acetylcholine, or adenosine triphosphate, cooling the perfusate from 37 C augmented the constriction and warming depressed it. cooling the vein in the absence of external stimulation did not cause the vein to constrict. When constricted with potassium chloride or barium chloride, the veins relaxed with cooling and constricted further with warming, indicating that the contractile process of the venous smooth muscle is depressed by cooling and facilitated by warming. Thus, the thermal effect on the venoconstriction induced by electric stimulation or drugs is not due to the direct eRect of temperature on the contractile machinery itself.