DIFFERENTIAL EXPRESSION OF THE PLASMA-MEMBRANE MG2-AMAZONENSIS IN FIBROBLASTS IN-VITRO( ATPASE AND CA2+ ATPASE ACTIVITY DURING ADHESION ANDINTERIORIZATION OF LEISHMANIA)

With ultrastructural cytochemistry we localized the activity of the pl asma membrane enzyme markers Mg2+ ATPase and Ca2+ ATPase during the in teraction between Leishmania amazonensis and in vitro primary culture fibroblasts. The expression of the enzymes was followed during the par asite adhesion and its interiorization. After the interiorization step , a striking difference was seen between the two enzymes studied when the parasite was found within the parasitophorous vacuole in the fibro blast cytoplasm. The activity of the Ca2+ ATPase found at the Leishman ia amazonensis plasma membrane during the attachment step of the infec tion remained also present inside the phagosome, whereas the Mg2+ ATPa se activity disappeared. So far, all the reports in the literature ref erred the presence of Ca2+ ATPase in Leishmania parasite only in the c rude ghost plasma membrane. The Ca2+ ATPase present at the parasite pl asma membrane may be involved in the regulation of calcium levels insi de the phagosome. Further characterization of this Ca2+ ATPase at the plasma membrane of the parasite, when still inside the phagosome, shou ld permit a better understanding of its functional role in maintaining the parasite surface membrane structure necessary for its existence.