Ca(2+) transport into an intracellular acidic compartment of Candida parapsilosis.
In this report, we study Ca2+ transport in permeabilized Candida parapsilosis spheroplasts prepared by a new technique using lyticase. An intracellular non-mitochondrial Ca2+ uptake pathway, insensitive to orthovanadate and sensitive to the V-H(+)-ATPase inhibitor bafilomycin A(1), nigericin and carbonyl cyanide p-trifluoromethoxyphenylhydrazone was characterized. Acidification of the compartment in which Ca2+ accumulated was followed using the fluorescent dye acridine orange. Acidification was stimulated by the Ca2+ chelator EGTA and inhibited by Ca2+. These results, when added to the observation that Ca2+ induces alkalization of a cellular compartment, provide evidence for the presence of a Ca2+/nH(+) antiporter in the acid compartment membrane. Interestingly, like in acidocalcisomes of trypanosomatids, the antioxidant 3,5-dibutyl-4-hydroxytoluene inhibits the V-H(+)-ATPase. In addition, the antifungal agent ketoconazole promoted a fast alkalization of the acidic compartment. Ketoconazole effects were dose-dependent and occurred in a concentration range close to that attained in the plasma of patients treated with this drug.
Milani
G
G
Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas 13083 970, SP, Brazil.
Schereiber
A Z
AZ
Vercesi
A E
AE
D000165:Acridine Orange / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000643:Ammonium Chloride / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002084:Butylated Hydroxytoluene / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002175:Candida / Q000187:drug effects / Q000378:metabolism*; D007654:Ketoconazole / Q000494:pharmacology; D018942:Macrolides; D009550:Nigericin / Q000494:pharmacology; D013104:Spheroplasts / Q000187:drug effects / Q000378:metabolism*; D013347:Subcellular Fractions; D014617:Vacuoles / Q000378:metabolism
D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D000975:Antioxidants; D018942:Macrolides; D000643:Ammonium Chloride; D002084:Butylated Hydroxytoluene; C040929:bafilomycin A1; D000255:Adenosine Triphosphate; D000165:Acridine Orange; D007654:Ketoconazole; D009550:Nigericin; D002118:Calcium