Effects of sodium and temperature on tension in isolated canine coronary artery

The effects of sodium and temperature on tension of isolated canine coronary arterial strips were studied. In 20 mEq. l(-1) K solution, the strength of tension was inversely related to the Na concentration. At 37 degrees C, the tension was significantly increased at 70 mEq. l(-1) Na and below. The tension was gradually suppressed by lowering of the temperature from 37 degrees C to 10 degrees C. At 10 degrees C, tension did not developed significantly at Na concentrations between 127 mEq. l(-1) and 12 mEq. l(-1). It was concluded that the decrease in Na concentrations increased the tension of the canine coronary artery and the lowering of temperature supressed the tension inducted by the decrease in Na concentrations.