Intracellular K+ activities in Aplysia gut: effects of transport inhibitors on the Na+ pump.
Na+ absorption by the Aplysia californica foregut is affected through an active Na+ transport mechanism located in the basolateral membrane of the epithelial absorptive cells. Since Cl- absorption by the Aplysia gut has been shown to be very different from that demonstrated in vertebrate gut, the present study was undertaken to discern if Na+ transport was also different from that observed in vertebrate preparations. Utilizing microelectrode technique, it was demonstrated that intracellular K+ activity is above electrochemical equilibrium in the Aplysia absorptive cells and that serosal ouabain, Ba2+ or Cd2+ abolished this asymmetry in K+ electrochemical potential. Neither bumetanide nor furosemide had any effect on intracellular K+ activities, mucosal membrane potentials or transepithelial potentials in the Aplysia gut preparation. These results are consistent with the operation of a basolateral Na+/K+ pump.
Department of Physiology, College of Medicine, University of Florida, Gainesville 32610, USA.
G A
GA
Gerencser
K M
KM
Kornette
D000818:Animals; D001048:Aplysia; D001464:Barium / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002034:Bumetanide / Q000494:pharmacology; D002104:Cadmium / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005665:Furosemide / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000201:enzymology; D008564:Membrane Potentials / Q000502:physiology; D008839:Microelectrodes; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000378:metabolism*
D004232:Diuretics; D004791:Enzyme Inhibitors; D002104:Cadmium; D002034:Bumetanide; D001464:Barium; D012965:Sodium Chloride; D010042:Ouabain; D005665:Furosemide; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium