Intracellular pH regulation in isolated hepatopancreas cells from the roman snail (Helix pomatia)

MANZL, C.; KRUMSCHNABEL, G.; SCHWARZBAUM, P.J.; CHABICOVSKY, M., DALLINGER, R.

JOURNAL OF EXPERIMENTAL ZOOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Año: 2004 p. 75 - 84

0022-104X

The mechanisms of intracellular pH (pHi) regulation were studied in isolated hepatopancreas cells from a terrestrial gastropod, Helix pomatia. The relationship between intracellular and extracellular pH indicated that pHi is actively regulated in these cells. At least three pHi-regulatory ion transporters were found to be present in these cells and to be responsible for the maintenance of pHi: an amiloride-sensitive Na+/H+ exchanger, a 4-acetamido-4´-isothiocyanostilbene-2,2´disulfonic acid (SITS)-sensitive, presumably Na+-dependent, Cl-/HCO3- exchanger, and a bafilomycin-sensitive H+-pump. Inhibition of one of these transporters alone did not affect steady state pHi, whereas incubation with amiloride and SITS in combination resulted in a significant intracellular acidification. Following the induction of intracellular acidosis by addition of the weak acid Na+propionate, the Na+/H+ exchanger was immediately activated leading to a rapid recovery of pHi towards the baseline level. Both the SITS-sensitive mechanism and the H+-pump responded more slowly, but were of similar importance for pHi recovery. Measurement of pHi recovery from acidification in the three discernible types of hepatopancreas cells with a video fluorescence image system revealed slightly differing response patterns, the physiological significance of which remain to be determined.