Apical Two-Pore Potassium Channels Support Anion Secretion Across Pig Vas Deferens Epithelia

Epithelia lining the vas deferens were shown to conduct potassium currents via one or more basolateral potassium channels, KCNQ1, KCNE1, SK3, and Maxi-K as demonstrated by mRNA and protein expression. We tested the hypothesis that two-pore (2P) potassium channels also contribute to the anion secretion across pig vas deferens epithelia. Confluent primary cultures of porcine vas deferens epithelial cells 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 both basolateral and apical application of bupivacaine, a 2P potassium channel blocker with an IC50 ~30μM. Isc stimulated by Riluzole, a 2P potassium channel activator, was also significantly reduced by bupivacaine confirming its inhibition of 2P potassium channels. RT-PCR demonstrated the presence of transcripts for KCNK1 (TWIK1). These data suggest that two-pore potassium channels may also support the anion secretion that is previously shown to be supported by basolateral potassium channels as described above. However, it remains to be determined if these apical and basolateral potassium channels work in concert to provide the correct luminal environment for the sperm in the vas deferens. Targeted modulation of such potassium conductances could be useful in managing male fertility. (Supported by NIH P20-RR17686)