Effect of K+ and K+ channel blockers on pancreatic HCO3-transport.
The present study investigated whether there is a K+ conductive pathway on the basolateral membrane of pancreatic duct cells. Small inter- and intralobular ducts were isolated from rat pancreas and perfused in vitro. Duct cells were impaled and the potential across the basolateral membrane (PDbl) was measured. The resting potential was -61 +/- 1 mV. Ouabain (3 mmol/l) depolarized PDbl by 11 mV. Increase in the bath K+ concentration from 5 to 20 mmol/l depolarized PDbl by 15-16 mV. The effect of K+ channel blockers was tested. Ba2+ (1 mmol/l) added to the bath depolarized PDbl by 23-26 mV, whereas TEA+ (50 mmol/l) depolarized PDbl only by 7-8 mV. Dibutyryl cyclic AMP (0.5 mmol/l) depolarized PDbl by 20-30 mV. The results show that on the basolateral membrane of pancreatic duct cells there is a (Na+ + K+)-ATPase and a K+ conductive pathway sensitive to Ba2+.
D000818:Animals; D001464:Barium / Q000494:pharmacology; D017609:Barium Compounds; D001485:Basement Membrane / Q000502:physiology; D001639:Bicarbonates / Q000378:metabolism*; D002712:Chlorides; D005260:Female; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D010183:Pancreatic Ducts / Q000502:physiology*; D011188:Potassium / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012633:Secretin / Q000502:physiology; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000502:physiology
D017609:Barium Compounds; D001639:Bicarbonates; D002712:Chlorides; D007473:Ion Channels; D013757:Tetraethylammonium Compounds; C024986:barium chloride; D012633:Secretin; D001464:Barium; D014660:Vasoactive Intestinal Peptide; D010042:Ouabain; D019789:Tetraethylammonium; D011188:Potassium