Electrogenic bicarbonate secretion in mouse gallbladder
| Autor: | M. E. Hickman, L J MacVinish, Alan W. Cuthbert, C. M. Curtis, L. C. Martin |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
medicine.medical_specialty
Physiology Bicarbonate Adenylate kinase Epithelium Membrane Potentials Mice chemistry.chemical_compound Chlorides 1-Methyl-3-isobutylxanthine Physiology (medical) Internal medicine medicine Animals Secretion Ion transporter Forskolin Ionophores Hepatology Ionomycin Gallbladder Colforsin Electric Conductivity Gastroenterology Bicarbonates medicine.anatomical_structure Endocrinology Bucladesine chemistry Acetazolamide Adenylyl Cyclases medicine.drug |
| Zdroj: | American Journal of Physiology-Gastrointestinal and Liver Physiology. 274:G1045-G1052 |
| ISSN: | 1522-1547 0193-1857 |
| Popis: | Mouse gallbladders (4 mm2) were investigated using the short-circuit current ( I sc) technique. Responses of 50 μA/cm2 were obtained in response to forskolin and agents that stimulated the adenylate cyclase system (IBMX and dibutyryl-cAMP). The calcium ionophore ionomycin increased I sc to 30% of the forskolin-stimulated increase. The forskolin-dependent current was inhibited 40% by acetazolamide but was insensitive to furosemide. Forskolin responses were dependent on the presence of bicarbonate ions; removal from both sides of the membrane or the basolateral side alone caused a significant reduction in responses. Removal of chloride ions from the basolateral side had no effect, while removal from the apical side caused a significant reduction in the forskolin responses, but only by 30%. It is argued that the remaining current (70%) cannot result from a parallel arrangement of a chloride channel and a chloride-bicarbonate exchanger and that bicarbonate is secreted through the apical membrane by a predominantly conductive mechanism. Apparently, forskolin converts a near electrically silent epithelium to an electrogenically secreting tissue. |
| Databáze: | OpenAIRE |
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