Regulation of intracellular pH in isolated periportal and perivenular rat hepatocytes.
BACKGROUND
Liver acinus shows a well-known metabolic zonation. The aim of this study was to investigate intracellular pH (pHi) regulation in isolated periportal (PP) and perivenular (PV) rat hepatocytes.


METHODS
2,7-bis(carboxyethyl)-5(6)-carboxy-fluorescein was used as pH-sensitive dye. Hepatocyte subconfluent monolayers were acid-loaded by exposure to 20 mmol/L NH4Cl and alkali-loaded by reducing external CO2 and HCO3- at an external pH of 7.4.


RESULTS
In the presence of HCO3-/CO2, (1) baseline pHi was higher in PP (7.25 +/- 0.018) than in PV hepatocytes (7.20 +/- 0.013) (P < 0.05); (2) pHi recovery from an acid load was 40% higher in PP than in PV hepatocytes (P < 0.02) and was inhibited by amiloride by 36% in PV and 7% in PP hepatocytes; (3) DIDS inhibited amiloride-independent pHi recovery from an acid load by 65% in PP and 52% in PV cells. In the absence of HCO3-/CO2, baseline pHi and pHi recovery from an acid load were not significantly different in PP and PV hepatocytes. pHi recovery from an alkali load was 30% higher in PV than in PP cells (P < 0.02).


CONCLUSIONS
Our data suggest that isolated PP rat hepatocytes show higher activity for Na(+)-HCO3- cotransport, whereas PV cells show greater activity for Cl-/HCO3- exchanger.
Benedetti
A
A
Department of Gastroenterology, University of Ancona, Italy.
Svegliati Baroni
G
G
Marucci
L
L
Mancini
R
R
Jezequel
A M
AM
Orlandi
F
F
D000818:Animals; D017920:Antiporters / Q000502:physiology; D027963:Chloride-Bicarbonate Antiporters; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008102:Liver Circulation / Q000502:physiology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017923:Sodium-Hydrogen Exchangers / Q000502:physiology
D017920:Antiporters; D027963:Chloride-Bicarbonate Antiporters; D017923:Sodium-Hydrogen Exchangers