Sodium-dependent, ethylisopropylamiloride-sensitive mechanisms regulate intracellular pH in human vascular smooth muscle.
1. The pH-sensitive dye 2,7-biscarboxy-ethyl-5(6)-carboxyfluorescein (BCECF) was used to examine the contribution of Na(+)-H+ exchange and bicarbonate-dependent processes to intracellular pH (pHi) regulation in cultured human vascular smooth muscle. 2. The recovery of pHi following an NH4Cl-induced acidosis was Na(+)-dependent and could be inhibited by ethylisopropylamiloride (200 mumols/L). Recovery was unaffected by the anion exchange inhibitor 4-acetamido-4'-isothio-cyano-stilbene-2,2'-disulfonic acid (200 mumols/L). 3. Recovery from intracellular acidosis was more rapid when bicarbonate ions were present in the extracellular medium. 4. The results suggest that Na(+)-H+ exchange as well as an Na(+)-dependent bicarbonate process, which can be inhibited by ethylisopropylamiloride, can influence the ability of smooth muscle to recover from intracellular acidosis.
Bobik
A
A
Alfred-Baker Medical Unit Laboratory, Prahran, Victoria, Australia.
Neylon
C B
CB
Little
P J
PJ
Cragoe
E J
EJ
Weissberg
P L
PL
D000136:Acid-Base Equilibrium / Q000187:drug effects / Q000502:physiology*; D000584:Amiloride / Q000031:analogs & derivatives* / Q000494:pharmacology; D001639:Bicarbonates / Q000494:pharmacology; D001826:Body Fluids / Q000378:metabolism*; D002478:Cells, Cultured; D006801:Humans; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
D001639:Bicarbonates; D000584:Amiloride; D012964:Sodium; C039614:ethylisopropylamiloride