Effect of Cytochalasin-B, Low Ca ++ Concentration, Iodoacetic Acid, and Quinacrine-HCl on the Attachment of Giardia Trophozoites In vitro

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Abstract
Giardia sp. trophozoites were isolated directly from the small intestines of rats and permitted to attach to polystyrene Petri dishes incubated at 37.degree. C. Attached trophozoites were treated in vitro with various agents which inhibit cell motility (cytochalasin-B, low Ca2+, colchicine) and metabolism (iodoacetic acid, 2,4-dinitrophenol) and chemotherapeutic agents (quinacrine-HCl, metronidazole). Trophozoite attachment was sensitive to cytochalasin-B, low Ca2+, iodoacetate and quinacrine-HCl. Contractile proteins (actin, myosin) have been demonstrated previously in the periphery of the ventral disc. The effect of cytochalasin-B and low Ca2+ concentrations on trophozoite attachment is consistent with the suggested role of contractile proteins in the mechanism of attachment. Energy for attachment may be derived from glycolysis. The effect of quinacrine-HCl on attachment was rapid (< 10 min with 10.0 .mu.g/ml). Its mode of action on attachment is not understood.