Intracellular pH regulation in isolated hepatopancreas cells from the Roman snail (Helix pomatia).
The mechanisms of intracellular pH (pHi) regulation were studied in isolated hepatopancreas cells from the Roman snail, 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 remains to be determined.
Manzl
Claudia
C
Institut für Zoologie und Limnologie, Abteilung für Okophysiologie, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria. Claudia.Manzl@uibk.ac.at
Krumschnabel
Gerhard
G
Schwarzbaum
Pablo J
PJ
Chabicovsky
Monika
M
Dallinger
Reinhard
R
D000136:Acid-Base Equilibrium / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D005453:Fluorescence; D006372:Helix, Snails / Q000502:physiology*; D043143:Hepatopancreas / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D010101:Oxygen Consumption; D011422:Propionates
D011422:Propionates; C029658:propionic acid