Patch-clamp study of single-channel and whole-cell K+ currents in guinea pig pancreatic acinar cells.
K+ channels in the plasma membrane of isolated guinea pig pancreatic acini were studied by patch-clamp single-channel and whole-cell current recording techniques. Three types of K+-permeable pores were found in excised patch experiments: Ca2+-activated nonselective cation channels with a unit conductance of approximately 25 pS that could be inhibited by ATP acting on the membrane inside, and two kinds of Ca2+- and voltage-activated K+-selective channels with unit conductances (in symmetrical K+-rich solutions) of about 200 and 30 pS, respectively. In intact cells, pentagastrin activation of currents through the 30 pS K+-selective pores was demonstrated. In these experiments pentagastrin was added to the bath solution and had no direct contact with the electrically isolated membrane area from which the single-channel currents were recorded, suggesting that the activation is mediated via an intracellular messenger system. Pentagastrin stimulation of voltage-gated K+ currents was also observed in whole-cell recording experiments. Results from these experiments suggest that in the stimulated condition the membrane electrical properties were dominated by the 30 pS K+-selective channels.
Suzuki
K
K
Physiological Laboratory, University of Liverpool, United Kingdom.
Petersen
O H
OH
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D010179:Pancreas / Q000187:drug effects / Q000502:physiology*; D010418:Pentagastrin / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D004533:Egtazic Acid; D019789:Tetraethylammonium; D010418:Pentagastrin; D011188:Potassium; D002118:Calcium