Potassium Conductance Identity In Porcine Vas Deferens Epithelia

Abstract

The ion transport mechanisms of the epithelia lining pig vas deferens play an important role in the modulation of luminal environment to which sperm are exposed. One or more basolateral K+ conductances are required to maintain membrane potential in presence of other ion transport mechanisms. We sought to determine the identity of such basolateral K+ conductance(s). The effects of various K+ channel inhibitors were tested on basolateral K+ conductance. Confluent primary cultures were used to measure short circuit current, Isc, an indicator of net ion flux. Forskolin-stimulated Isc that is consistent with anion secretion was significantly reduced by basolateral but not apical application of Ba2+ and clofilium. Clotrimazole, a lipophillic compound also inhibited Isc in a concentration dependent manner. RT-PCR demonstrated the presence of transcripts for SK3, Maxi-K, Kv7.1, and KCNE1. Maxi-K and Kv7.1 were localized to basolateral membrane using confocal microscopy confirming their expression at protein level. The above findings suggest that the clotrimazole sensitivity observed may be attributed to SK3 and Maxi-K while clofilium sensitivity due to Kv7.1 and KCNE1. These data suggest that net ion transport in pig vas deferens epithelia requires the support of multiple K+ conductances. Targeted modulation of such potassium conductances could be useful in managing male fertility. Supported by NIH P20-RR17686