Referenced in: none

Automatically associated channels: ClC4 , ClCK1 , Slo1

Title: A chloride conductance exhibiting bicarbonate conductivity in renal inner medullary collecting duct cells.

Authors: Juan J Bolívar, César O Lara-Figueroa, Ramón H Martínez-Mayorquin, Florencio Monroy-Romero, Gabina Arenas

Journal, date & volume: Gen. Physiol. Biophys., 2014 , 33, 321-34

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/24595846

Abstract
The anion conductance in primary cultures of rat inner medullary collecting duct cells was studied using perforated-patch whole-cell clamp technique. Depolarizations above 0 mv induced an outward anionic current with a time-dependent activation (Iovt) exhibiting a similar conductivity to Cl- and HCO3-. Iovt showed half-maximal activation around 32 mV with a slope factor of 23 mV, and showed a voltage-dependent activation time course that was well fitted by a sum of two exponential functions. Iovt was potentiated when external pH or external Ca2+ was increased and was blocked by external DIDS, DPC and furosemide. These characteristics of Iovt resemble that of the ClC-K1 channels mediated currents; however, anion substitution studies showed that Iovt exhibits a Br->Cl->I->NO3- conductivity sequence, different from that observed in the ClC-K1 channels-mediated conductance. We suggest that, in inner medullary collecting duct cells, ClC-K channels of an unidentified type give rise to this Cl- and HCO3- conductance. This is the first study of a channel-mediated HCO3- current in kidney tubular cells.