Effects of serosal anion composition on the permeability properties of rabbit urinary bladder.
This study describes the effects of serosal Cl- and HCO3- substitution on transepithelial Na+ transport and basolateral membrane properties of the rabbit urinary bladder. Replacement of Cl- with NO3-, SCN-, and Br- had no effect on transepithelial Na+ transport or the basolateral membrane potential (Vbl). However, gluconate, isethionate, and cyclamate (anions that were shown previously to be not as permeable as Cl- through the basolateral membrane anion channel), decreased transepithelial Na+ transport and depolarized Vbl. Replacement of HCO3- also produced a decrease in transepithelial Na+ transport and a depolarization of Vbl. Utilizing conventional and K+-specific microelectrodes, we found the depolarization to be due to a reduction in basolateral K+ conductance. This depolarization was reversible only when Cl- was returned to the serosal solution, the normally permeant anion NO3- being unable to affect repolarization, suggesting that both the K+ and Cl- conductance are reduced during depolarization. A lag period of some 4 min preceded the repolarization of Vbl. The Na+-H+ exchange blocker amiloride prolonged the lag phase associated with repolarization, whereas niflumic acid, a Cl-(-)HCO3- exchange blocker (in red blood cells) reduced the magnitude of Vbl repolarization. Because of the possible involvement of the exchangers it is believed that the lag phase represents a volume-dependent and/or pH-dependent reactivation of the basolateral membrane conductances.
Donaldson
P J
PJ
Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77550.
Chen
L K
LK
Lewis
S A
SA
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology; D002034:Bumetanide / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D004553:Electric Conductivity; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009544:Niflumic Acid / Q000494:pharmacology; D010539:Permeability; D011817:Rabbits; D012964:Sodium / Q000378:metabolism; D001743:Urinary Bladder / Q000502:physiology*
D001639:Bicarbonates; D002712:Chlorides; D002034:Bumetanide; D009544:Niflumic Acid; D000584:Amiloride; D012964:Sodium