Energetics of potassium ion transport in Aplysia gut.
Basolateral membranes of Aplysia californica foregut epithelia contain an ATP-dependent Na(+)/K(+) transporter (Na(+)/K(+) pump or Na(+)/K (+) -ATPase). This Na(+)/K(+) pump accounts for both the intracellular Na(+) electrochemical potential (micro) being less than the extracelluar Na(+) micro and the intracellular K(+) micro being more than the extracellular K(+ ) micro. Also, K(+) channel activity resides in both luminal and basolateral membranes of the Aplysia foregut epithelial cells. Increased activity of the Na(+)/K(+) pump, coupled to luminal and basolateral membrane depolarization altered the K(+) transport energetics across the basolateral membrane to a greater extent than the alteration in K(+) transport energetics across the luminal membrane. These results suggest that K(+) transport, either into or out of the Aplysia foregut epithelial cells, is rate-limiting at the basolateral membrane.
Department of Physiology, College of Medicine, University of Florida, Gainsville, FL 32610, USA.
George A
GA
Gerencser
Stanley Y
SY
Loo
Kuuleialoha M
KM
Cornette
Jianliang
J
Zhang
D000621:Aminoisobutyric Acids / Q000494:pharmacology; D000818:Animals; D001048:Aplysia / Q000378:metabolism*; D001693:Biological Transport, Active / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004064:Digestive System / Q000187:drug effects / Q000378:metabolism; D004734:Energy Metabolism; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000621:Aminoisobutyric Acids; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium