Cl- channels in basolateral renal medullary vesicles. IX. Channels from mouse MTAL cell patches and medullary vesicles.
The experiments reported herein compared Cl- channels fused into bilayers from rabbit outer medullary vesicles with Cl- channels in excised patches of basolateral membranes from cultured mouse medullary thick ascending limb (MTAL) cells and evaluated whether the latter were plausible candidates for the Cl- channels mediating net NaCl absorption in microperfused mouse MTAL segments. The unique signature characteristics of Cl- channels incorporated into lipid bilayers from outer medullary vesicles include activation of open probability (Po) by increases in the Cl- concentrations bathing intracellular faces; activation of Po by protein kinase A (PKA) + ATP, when the Cl- concentrations bathing intracellular faces are low; and no effect of PKA + ATP on Po with high cytoplasmic-face Cl- concentrations. These same properties were observed in Cl- channels studied using excised patches of basolateral membranes from mouse MTAL cells. Moreover, in both bilayers and in excised patches, the sharpest fractional increase in Cl- channel Po occurred with cytosolic-face Cl- concentration increases to values similar to the antidiuretic hormone (ADH)-dependent values of intracellular Cl- activity in microperfused mouse MTAL segments, and these fractional Po increases were adequate to account quantitatively for the ADH-dependent increase in basolateral membrane Cl- conductance in microperfused mouse MTAL segments. Thus the excised-patch basolateral Cl- channels reported here are reasonable candidates for those mediating net Cl- absorption in the MTAL.
Reeves
W B
WB
Department of Internal Medicine, University of Arkansas College of Medicine, Little Rock, USA.
Winters
C J
CJ
Filipovic
D M
DM
Andreoli
T E
TE
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D018118:Chloride Channels / Q000378:metabolism* / Q000502:physiology; D002712:Chlorides / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004553:Electric Conductivity; D004594:Electrophysiology; D007679:Kidney Medulla / Q000378:metabolism*; D008138:Loop of Henle / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D018408:Patch-Clamp Techniques; D011817:Rabbits
D018118:Chloride Channels; D002712:Chlorides; D000255:Adenosine Triphosphate; D017868:Cyclic AMP-Dependent Protein Kinases