THE EFFECT OF PROCAINE ON THE URINARY BLADDER SMOOTH MUSCLE OF BULLFROGS

Abstract

The effect of procaine on the bullfrog urinary bladder smooth muscle was studied with the Rapid Cooling technique, with the following results.
1. Procaine induced contracture in the bullfrog urinary bladder smooth muscle in normal Ringer's solution, but it induced a relaxing effect in isotonic potassium Ringer's solution.
2. Procaine-induced contracture was inhibited in a low pH Ringer's solution and potentiated in a high solution.
3. Mn++ inhibited the procaine-induced contracture, but tetrodotoxin produced no effect.
4. The bullfrog urinary bladder smooth muscle contracted in normal and potassium Ringer's solutions when the temperature of the solution was lowered rapidly from 26-28° to 2-4°(Rapid Cooling Contracture, RCC).
5. The RCC of the bullfrog urinary bladder in normal and potassium Ringer's solutions was potentiated by procaine, and was inhibited by Mn++.
6. The mechanism of the procaine-induced contracture and the effect of Mn++ are discussed with respect to the origin of Ca++. It is postulated that the effect of procaine on bullfrog urinary bladder smooth muscles was produced by mobilization of intracellular bound Ca++, and the inhibitory effect of Mn++ on the procaine-induced contracture and the rapid cooling contracture may be produced by inhibition of its mobilization.