title: Effects of angiotensin II and vasopressin on intracellular pH of glomerular mesangial cells.
abstract: We investigated changes in intracellular pH (pHi) of cultured rat glomerular mesangial cells (MCs) exposed to angiotensin II (ANG II) and arginine vasopressin (AVP). pHi of quiescent MCs, passage 2-5, and grown on glass cover slips, was assessed by spectrofluorometry using the pH-sensitive dye, 2,7-biscarboxyethyl-5(6)-carboxyfluorescein (BCECF). The steady-state pHi of MCs in a pH 7.4, HCO3-free N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES)-buffered solution was 7.10 +/- 0.02 (n = 68) and in a pH 7.4, HCO3-containing solution, was 7.23 +/- 0.03 (n = 47) (P less than 0.01). The pHi recovery following an NH+4-induced acid load was inhibited by removal of Na+ from the bath or by addition of the amiloride analogue, ethyl isopropyl amiloride (EIPA). These effects were observed in MCs bathed in HEPES- or in HCO3-buffered solutions, consistent with the action of a Na+-H+ exchanger. When cells were bathed in HEPES, a 10-min exposure to ANG II or AVP (10(-10) to 10(-6) M) caused early and transient acidification of MCs (maximal pH change was -0.10), followed by gradual alkalinization (maximal pHi change +0.15 above the initial value). The increase of pHi was dependent on the presence of Na+ in the bath and was inhibited by EIPA. In the presence of HCO3, ANG II or AVP induced merely a small gradual acidification of MCs (pHi change -0.05). These findings demonstrate that MCs utilize a Na+-H+ exchanger for acid extrusion.(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06516.
authors: M B
authors: MB
authors: Ganz
authors: G
authors: G
authors: Boyarsky
authors: W F
authors: WF
authors: Boron
authors: R B
authors: RB
authors: Sterzel
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002021:Buffers; D002478:Cells, Cultured; D006863:Hydrogen-Ion Concentration; D007678:Kidney Glomerulus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008297:Male; D009550:Nigericin / Q000494:pharmacology; D051381:Rats
chemical_list: D002021:Buffers; D000804:Angiotensin II; D001127:Arginine Vasopressin; D009550:Nigericin