title: Membrane effects of trifluoperazine, dibucaine and praziquantel on human erythrocytes.
abstract: Trifluoperazine (TFP) is a potent antipsychotic agent, dibucaine (DBC) is a local anaesthetic and praziquantel (PZQ) is a highly effective agent against schistosomiasis. The present work was conducted to (i) investigate the cytotoxic effects of TFP, DBC and PZQ on human erythrocyte membranes; and (ii) compare the alterations induced by the cationic drugs (TFP and DBC) with those induced by the uncharged compound (PZQ), in an attempt to have a better insight on the pathways of each drug-membrane interaction. The erythrocyte morphological alterations induced by sublytic concentrations of TFP, DBC and PZQ were evaluated by scanning electron microscopy and expressed quantitatively by the morphological index. Haemolysis and release of membrane lipids (phospholipids and cholesterol) produced by selected concentrations of TFP, DBC and PZQ, were compared with those resulting from the corresponding triple concentrations of each drug. Our results showed that the uncharged molecule of PZQ induces the same morphological alterations (stomatocytosis) as the cationic drugs TFP and DBC. Haemolysis was shown to vary with the drug used and to be concentration-dependent, with values approximately 10-fold more elevated for TFP and DBC than for PZQ, which revealed a maximum of 6% haemolysis for the highest concentration tested. Different concentration-response curves were obtained for lipid elution, although the profiles of cholesterol and phospholipids released were similar for all drugs. Nevertheless, at a fixed rate of 50% haemolysis, TFP induced a approximately 2-fold increment in the elution of cholesterol when compared with that produced by DBC (P<0. 05). The different effects induced by TFP, DBC and PZQ on erythrocyte morphology, haemolysis and lipid exfoliation are related to the physical and chemical characteristics of each compound. These results suggest that distinct cell membrane interaction pathways lead to drug-specific mechanisms of cytotoxicity.
authors.affiliation: Department of Biochemistry, Institute of Biology, State University of Campinas, SP, Campinas, Brazil.
authors.forename: S V
authors.initials: SV
authors.lastname: Malheiros
authors.forename: M A
authors.initials: MA
authors.lastname: Brito
authors.forename: D
authors.initials: D
authors.lastname: Brites
authors.forename: N C
authors.initials: NC
authors.lastname: Meirelles
mesh_terms: D000328:Adult; D002784:Cholesterol / Q000097:blood; D003992:Dibucaine / Q000494:pharmacology*; D004910:Erythrocyte Membrane / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D004912:Erythrocytes / Q000187:drug effects / Q000648:ultrastructure*; D006461:Hemolysis; D006801:Humans; D066298:In Vitro Techniques; D008563:Membrane Lipids / Q000097:blood; D008855:Microscopy, Electron, Scanning; D010743:Phospholipids / Q000097:blood; D011223:Praziquantel / Q000494:pharmacology*; D014268:Trifluoperazine / Q000494:pharmacology*
chemical_list: D008563:Membrane Lipids; D010743:Phospholipids; D014268:Trifluoperazine; D011223:Praziquantel; D002784:Cholesterol; D003992:Dibucaine