Intracellular alkalinization caused by chloride removal in the smooth muscle of guinea-pig vena cava.
Intracellular pH (pHi) of smooth muscle of guinea-pig vena cava was measured with a pH-sensitive dye, 4',5'-dimethyl-5-(and -6-)carboxyfluorescein. Sustained intracellular alkalinization (pHi 7.46) was produced when Cl- was replaced with gluconate in the presence of HCO3-, but not produced in the absence of HCO3-. Alkalinization caused by Cl- removal was nearly completely blocked by 200 microM DIDS, a Cl- transport inhibitor. In the solution containing normal Cl- concentration, pHi (7.15) was not affected by DIDS, and pHi was also nearly the same in the presence and absence of HCO3-. When full alkalinization was developed in Cl(-)-deficient solution, HCO3- removal produced only a weak recovery. A carbonic anhydrase inhibitor, acetazolamide (100 microM) had no clear effect on pHi in both normal and Cl(-)-deficient solutions. Intracellular acidification caused by Na+ removal was much less when NaCl was replaced with sucrose than with N-methyl-D-glucamine chloride. It is concluded that when Cl- is removed, pHi can be strongly altered by a Cl(-)-HCO3- exchange mechanism in the guinea-pig vena cava. A contribution of this mechanism to pHi is, however, probably rather minor under physiological conditions.
Matsumoto
T
T
Department of Physiology, School of Medicine, Nagoya University, Japan.
Tomita
T
T
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000086:Acetazolamide / Q000494:pharmacology; D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides / Q000378:metabolism*; D005260:Female; D006168:Guinea Pigs; D006863:Hydrogen-Ion Concentration; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D014682:Vena Cava, Inferior; D014683:Vena Cava, Superior
D001639:Bicarbonates; D002352:Carrier Proteins; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides; D000643:Ammonium Chloride; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000086:Acetazolamide; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid