The role of K+ ions on the response to carbachol of calf coronary artery and cardiac vein during cooling.

The role of K+ ions on the vasoconstrictions induced by carbachol during cooling (28 degrees C) in the endothelium of a denuded calf coronary artery and cardiac vein (noncutaneous vessel) was studied. Carbachol (10(-9) - 3 x 10(-4) M) induced concentration-dependent contractions at both 37 degrees C and 28 degrees C. The sensitivity, but not the maximal response, of carbachol (10(-9) -3 x 10(-4) M) was significantly lower at 28 degrees C than at 37 degrees C. Cooling to 28 degrees C after treatment with tetraethylammonium (TEA, 10(-3) M) or ouabain (10(-5) M), after incubation in K+-free medium increased the sensitivity to carbachol in both preparations. The results suggest a role for K+ ions in the cooling-induced changes of noncutaneous vessels.