Abstract
1. A study was carried out of the effect of caffeine and low temperature on smooth muscle of the toad bladder.
2. Spontaneous rhythmic contraction of smooth muscle is suppressed by the action of caffeine.
3. Rapid cooling elicits muscle contraction. Although spontaneous rhythmic contraction of the smooth muscle disappears with the application of caffeine, contraction is elicited by a rapid cooling treatment.
4. Unlike skeletal muscle, smooth muscle does not contract with upon repeated rapid cooling.
5. When caffeinized muscle, immersed in Ringer's solution, of which part of the sodium has been replaced with an equivalent amount of sucrose, is subjected to rapid cooling, the tension of the muscle increases in proportion to the amount substituted.
