Contractile Response of the Rat Vas Deferens to Electrical Field Stimulation, Phenylephrine and Acetylcholine under Hypoxia

Suh, Hong Jin; Lee, Dong Hwan; Yoon, Jai Young; Park, Young Hyun

Abstract

PURPOSE: The proper functioning of all smooth muscle structures depends on the ability of normal blood to deliver oxygen and nutrients to the muscles. In addition, hypoxia has been shown to inhibit the contractile response to various forms of stimulation. The contractile response of the vas deferens can be divided into two phases: an initial rapid increase in tension(phasic contraction) and prolonged period of sustained tension(tonic contraction). The aim of this study was to determine the effect of hypoxia on the ability of the vas deferens to sustain tension .
MATERIALS AND METHODS
The isolated strips of rat vas deferens were studied for Isometric tension measurement under normoxia and hypoxia in the organ chamber. Effects of phenylephrine(Phe) and acetylcholine(Ach) on the rat vas deferens tissue were monitored under normoxia and hypoxia.
RESULTS
The results of these studies can be summerized as follows; (1) hypoxia induced time dependent decrease in both phasic and tonic contraction in response to electrical field stimulation(4 and 32Hz). The rate of inhibition of the tonic contraction was significantly and immediatly greater than that of the phasic contraction in both the prostatic and epididymal vas deferens, which was much prominent. (2) hypoxia(5min) increased the basal tension of prostatic vas deferens only to Phe(10(-3)M) and Ach(10(-3)M). But In the response of epididymal vas deferens to Phe(10(-3)M) and Ach(10(-3)M), rhythmic contractions disappeared.
CONCLUSIONS
In conclusion, the contractile response of rat Vas deferens to electrical field stimulation under hypoxia were decreased and basal tension of prostatic vats deferens to Phe(10(-3)M) or Ach(10(-3)M) was increased This effect can interfere the sperm expulsion by changing normal contractability of the vas deferens.