MYOINOSITOL TRISPHOSPHATE SENSITIVE CALCIUM STORES IN ENTAMOEBA-HISTOLYTICA

Calcium mobilization from internal stores of the parasitic protozoan E ntamoeba histolytica was studied by fluorescence measurements of the c alcium indicator quin 2 in saponin permeabilized amoeba. Both Ins 1,4, 5)P3 and Ins(2,4,5)P3 could release calcium equally well from permeabi lized E. histolytica. On an average, about 40% of the A23187 releasabl e calcium pool could be mobilized by 2 muM InsP3. Neither GTP nor cAMP could influence InsP3-mediated Ca2+ mobilization. InsP3-mediated Ca2 release from internal stores of E. histolytica occurred in an InsP3 r eceptor-dependent manner. Differential interference contrast microscop y revealed that increased motility and pseudopod formation could be pr oduced in E. histolytica through InsP3 treatment.