Regulation of intracellular pH in rat lactotrophs: involvement of anionic exchangers.
Regulation of the intracellular pH (pHi) of normal rat lactotrophs was studied. As this cell type, cultured with 10% FCS, can achieve a relatively alkaline pHi (7.3-7.5), we investigated the presence of a mechanism based on Cl-/HCO3- exchange. Using the pHi-sensitive probe SNARF-1 (seminaphtorodafluor) in its permeant form, SNARF-1/AM, we studied pHi recovery after acidic loading in individual cells with a microspectrofluorometric approach. We showed the involvement of anionic exchange in lactotroph cell pHi regulation. Acute CO2-bicarbonate cell acidic loading combined with external Cl- depletion induces the activation of a Cl-/HCO3- exchange. This exchange is 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid sensitive and corresponds to the type 3 anionic exchanger (AE3). However, after nigericin acidification, Na+/H+ exchange can also participate in recovery. In addition, incubation experiments strongly suggest that a 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid-insensitive anionic exchanger (type 2 anionic exchanger or AE2) is present in rat lactotrophs. The presence and involvement of carbonic anhydrase in pHi regulation have been demonstrated. Finally, using Northern blot and reverse transcription-PCR techniques, messenger RNAs for both AE2 and AE3 were identified in anterior pituitary cell extracts. We concluded that in normal rat lactotrophs, pHi regulation is achieved by a complex system in which Cl-/HCO3- exchange has a pivotal role.
Garcia
L
L
Departement de Fisiologia, Facultad de Salud, Universidad del Valle, Cali, Columbia.
Boué-Grabot
E
E
Garret
M
M
Sartor
P
P
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017920:Antiporters / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D001578:Benzopyrans; D015152:Blotting, Northern; D002256:Carbonic Anhydrases / Q000032:analysis; D027963:Chloride-Bicarbonate Antiporters; D004247:DNA / Q000032:analysis / Q000737:chemistry / Q000235:genetics; D004140:Dinitrophenols / Q000494:pharmacology; D005260:Female; D005456:Fluorescent Dyes; D006651:Histocytochemistry; D006863:Hydrogen-Ion Concentration; D017879:Isothiocyanates / Q000494:pharmacology; D009284:Naphthols; D009550:Nigericin / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000737:chemistry / Q000166:cytology* / Q000502:physiology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis / Q000737:chemistry / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D012235:Rhodamines; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers / Q000502:physiology; D014475:Uncoupling Agents / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D017920:Antiporters; D001578:Benzopyrans; D027963:Chloride-Bicarbonate Antiporters; D004140:Dinitrophenols; D005456:Fluorescent Dyes; D017879:Isothiocyanates; D009284:Naphthols; D012333:RNA, Messenger; D012235:Rhodamines; D017923:Sodium-Hydrogen Exchangers; D014475:Uncoupling Agents; C091666:seminaphthorhodaminefluoride; C037152:isothiocyanic acid; D004247:DNA; D012964:Sodium; D002256:Carbonic Anhydrases; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D009550:Nigericin