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Ion transport properties of small airways
Author(s) -
Shamsuddin A K M,
Quinton Paul M
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.764.1
Subject(s) - chemistry , ibmx , amiloride , paracellular transport , ion transporter , transepithelial potential difference , conductance , biophysics , bumetanide , membrane potential , reversal potential , electrophysiology , ion , sodium , permeability (electromagnetism) , patch clamp , medicine , membrane , biochemistry , forskolin , receptor , mathematics , organic chemistry , combinatorics , biology
The ion transport properties of small airways have been neglected because intact bronchiolar epithelia are small and extremely difficult to obtain without trauma. To accommodate the small size of the tissue, we designed a special micro‐Ussing chamber (Area=1mm 2 ). Constant current pulses (0.5–1.0 μA) were passed across pig airway tissue and basic electrophysiolgical properties were determined. In bilateral 150 mM NaCl Ringers Vt was −1.1±0.2 mV and Rt was 89.4±9.7 Ω‐cm 2 . When gluconate replaced luminal chloride, Vt (−33.6±2.7 mV) and Rt (239.0±37.8 Ω‐cm 2 ) increased significantly. Adding Fsk plus IBMX further hyperpolarized Vt (−43.0±2.1 mV) and decreased Rt (229.1±33.7 Ω‐cm 2 ). Anion selectivity sequences are grossly the same as for CFTR. The 2:1 NaCl dilution potentials indicate that Cl − is significantly more permeable than Na + . Cl − conductances were inhibited by CFTR inhibitors. Luminal amiloride depolarized Vt and significantly increased Rt. G Na was not affected by Fsk. Bi‐ionic diffusion potentials for NMDG vs. Na + indicate a slightly Na + selective paracellular shunt. Small airways are highly conductive due to a major constitutively active Cl − conductance, probably CFTR. These results give the first measurements of transepithelial properties of isolated native small airways <1.5 mm (i.d.). Support: The Nancy Olmsted Trust and NIH (RO1‐ HL084042 ).