Apical and basolateral membrane ionic channels in rabbit urinary bladder epithelium.
This paper reviews the properties and regulation of single amiloride-sensitive Na+ channels in the apical membrane, and Cl- and K+ channels in the basolateral membrane of rabbit urinary bladder. According to fluctuation analysis, there is an average of one amiloride-sensitive Na+ channel for every 40 micron2 of apical membrane. Each Na+ channel passes 0.7 pA of current under normal, short-circuit conditions. Apical channels are hydrolysed by the endogenous enzyme urokinase, which is released into the urine by the kidney. After exposure to urokinase, the Na+ channel loses its amiloride sensitivity, and eventually becomes unstable in the membrane. The selectivity and kinetic properties of single anion and K+ channels in the basolateral membrane were also studied using the patch clamp technique. The properties of these channels are discussed in terms of the regulation of transepithelial Na+ transport.
S A
SA
Lewis
J W
JW
Hanrahan
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D002712:Chlorides / Q000378:metabolism; D004848:Epithelium / Q000502:physiology; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008433:Mathematics; D008954:Models, Biological; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D012964:Sodium / Q000378:metabolism; D001743:Urinary Bladder / Q000502:physiology*; D014568:Urokinase-Type Plasminogen Activator / Q000494:pharmacology
D002712:Chlorides; D007473:Ion Channels; D000584:Amiloride; D012964:Sodium; D014568:Urokinase-Type Plasminogen Activator; D011188:Potassium