title: Temperature-induced rapid increase in cytoplasmic free Ca2+ in pathogenic Leishmania donovani promastigotes.
abstract: We demonstrate that the cytoplasmic free Ca2+ concentration in three virulent Leishmania donovani promastigote strains is maintained at 20-30 nM level whereas the avirulent promastigotes maintain [Ca2+]i at 80-100 nM. Rapid exposure of virulent promastigotes to higher physiological temperature increases [Ca2+]i many-fold. Use of CaCl2, EGTA and Mn2+ confirmed that both release of Ca2+ from internal pool(s) and influx from outside milieu are responsible for this increase in [Ca2+]i. Application of oligomycin, CN-, and nigericin indicated the non-mitochondrial pHi sensitive pool as the possible intracellular origin for internal Ca2+ release. Exposure of these cells to acidic environment had no influence on [Ca2+]i. In contrast, the avirulent promastigotes or freshly isolated amastigotes had shown no effect of heat-shock or pH shock on [Ca2+]i of these cells. Our results indicate that the upward shift in temperature may play a role in signal transduction events in morphogenetic transformation of L. donovani promastigotes that involves mobilization of Ca2+ in cytoplasm.
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D007893:Leishmania donovani / Q000302:isolation & purification / Q000378:metabolism* / Q000472:pathogenicity*; D007898:Leishmaniasis, Visceral / Q000469:parasitology; D008345:Manganese / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009550:Nigericin / Q000494:pharmacology; D009840:Oligomycins / Q000494:pharmacology; D012966:Sodium Cyanide / Q000494:pharmacology; D013045:Species Specificity; D013050:Spectrometry, Fluorescence; D013696:Temperature; D014774:Virulence
chemical_list: D009840:Oligomycins; D000001:Calcimycin; D008345:Manganese; D012966:Sodium Cyanide; D009550:Nigericin; D002118:Calcium