Evidence for electrogenic Na-glucose cotransport in tracheal epithelium.
We demonstrate that electrogenic glucose coupled Na+ absorption accounts for about 20% of the residual, amiloride and Cl- insensitive, Na+ transport in isolated (equine) trachea. Either glucose removal from the mucosal side or addition of 10(-4) M phloridzin, a known pharmacological inhibitor of Na-glucose cotransport in small intestine and kidney proximal tubule, results in depolarization (lumen referenced to bath) of the transepithelial potential difference (Vt) and in a significant decrease of the equivalent short circuit current Ieq by 4 mV and 4 microA/cm2, respectively, without affecting the transepithelial resistance (Rt). Neither glucose removal nor the application of phloridzin on the basolateral side have a significant or consistent effect on the bioelectric parameters.
Joris
L
L
Division of Biomedical Sciences, University of California, Riverside 92521-0121.
Quinton
P M
PM
D000818:Animals; D001692:Biological Transport; D004553:Electric Conductivity; D004594:Electrophysiology; D004848:Epithelium / Q000502:physiology; D005947:Glucose / Q000378:metabolism*; D006736:Horses; D008564:Membrane Potentials / Q000187:drug effects; D010695:Phlorhizin / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D014132:Trachea / Q000502:physiology*
D012964:Sodium; D010695:Phlorhizin; D005947:Glucose