CFTR mediated chloride secretion in the avian renal proximal tubule.
Publication/Presentation Date
1-1-2012
Abstract
In primary cell cultures of the avian (Gallus gallus) renal proximal tubule parathyroid hormone and cAMP activation generate a Cl(-)-dependent short circuit current (I(SC)) response, consistent with net transepithelial Cl(-) secretion. In this study we investigated the expression and physiological function of the Na-K-2Cl (NKCC) transporter and CFTR chloride channel, both associated with Cl(-) secretion in a variety of tissues, in these proximal tubule cells. Using both RT-PCR and immunoblotting approaches, we showed that NKCC and CFTR are expressed, both in proximal tubule primary cultures and in a proximal tubule fraction of non-cultured (native tissue) fragments. We also used electrophysiological methods to assess the functional contribution of NKCC and CFTR to forskolin-activated I(SC) responses in filter grown cultured monolayers. Bumetanide (10 μM), a specific blocker of NKCC, inhibited forskolin activated I(SC) by about 40%, suggesting that basolateral uptake of Cl(-) is partially mediated by NKCC transport. In monolayers permeabilized on the basolateral side with nystatin, forskolin activated an apical Cl(-) conductance, manifested as bidirectional diffusion currents in the presence of oppositely directed Cl(-) gradients. Under these conditions the apical conductance appeared to show some bias towards apical-to-basolateral Cl(-) current. Two selective CFTR blockers, CFTR Inhibitor 172 and GlyH-101 (both at 20 μM) inhibited the forskolin activated diffusion currents by 38-68%, with GlyH-101 having a greater effect. These data support the conclusion that avian renal proximal tubules utilize an apical CFTR Cl(-) channel to mediate cAMP-activated Cl(-) secretion.
Volume
161
Issue
1
First Page
53
Last Page
60
ISSN
1531-4332
Published In/Presented At
Laverty, G., Anttila, A., Carty, J., Reddy, V., Yum, J., & Arnason, S. S. (2012). CFTR mediated chloride secretion in the avian renal proximal tubule. Comparative biochemistry and physiology. Part A, Molecular & integrative physiology, 161(1), 53–60. https://doi.org/10.1016/j.cbpa.2011.09.005
Disciplines
Dentistry | Medicine and Health Sciences
PubMedID
21964154
Department(s)
Department of Dental Medicine
Document Type
Article