Contractile Responses of Rat Seminal Vesicle to Field Stimulation, Phenylephrine, Acetylcholine and KCI in Anoxia

Lee, Dong Hwan; Suh, Hong Jin

Abstract

Oxygen supply is considered to one of the most important local factors influencing the contractility of smooth muscle. However, the effect of anoxia on the contractility is not uniform throughout the organs containing smooth muscle. This study was undertaken to evaluate the changes of the contractility of rat seminal vesicle to field stimulation, phenylephrine (Phe), acetylcholine (Ach), and KCI in anoxia. Seminal vesicle was rapidly removed from Sprague-Dawley rats which had been killed by cervical dislocation. Spiral segments were mounted in organ bath containing Tyrode's solution at 37'C and equilibrated with 95% O2 and 5% CO2 for 1 hr. Anoxia was produced by changing the gas mixture to 95% N2, 5% CO2. The effect of anoxia on the contractile responses to field stimulation, Phe, Ach, and KCI was determined at different times after the initiation of anoxia. The results of this study can be summarized as follows: 1. Anoxia induced a time-dependent decrease of the contractile responses to field stimulation (30 and 60 Hz). 2. Anoxia potentially inhibited the rhythmic contractions to Phe and Ach. However, the basal tension showed a transient relaxation followed by a contraction after 10 min. 3. In tonic contraction produced by KCI, anoxia caused a transient relaxation followed by a further contraction. However, this anoxic contraction was not inhibited by verapamil (0.1M). This study demonstrated that anoxia may cause poor contractile responses to field stimulation and increased basal tension to Phe, Ach, and KCI. But anoxic contraction by KCI was not inhibited by verapamil, which means that this anoxic contraction of rat seminal vesicle is not mediated by Ca++ influx.