title: The haemolytic effect of verapamil on erythrocytes exposed to varying osmolarity.
abstract: The haemolytic effect of verapamil on red blood cells (RBCs) exposed to varying osmolarity was investigated. The experimental approach used a modified red cell haemolysis assay with concentrations of verapamil ranging from 50-1500 microM compared to drug free controls. The time-course of haemolytic effects was also investigated. We also briefly determined the haemolytic effects of verapamil in Ca2+-free conditions (with added EGTA). In conditions representing decreasing osmolarity (dilution from 140-0 mM NaCl) there was a significant increase in erythrocyte haemolysis that was also dependent on verapamil concentration (ANOVA, p<0.05). The red cells also showed a significantly increased rate of haemolysis over 5 h with increasing verapamil concentration (ANOVA, p<0.05). The degree of RBC hypotonic haemolysis was significantly increased in a Ca2+-free medium (+EGTA) compared to normal saline and this effect was exacerbated by additions of verapamil (ANOVA, p<0.05). Overall the data suggested that verapamil can cause haemolysis of RBCs in a predictable time- and concentration-dependent manner, and that verapamil increases the fragility of the erythrocytes further during hypotonic osmotic stress and Ca2+-free conditions. The mechanism of verapamil-dependent haemolysis could be directly related to the observed biphasic concentration-effect and could consequently involve several ion transport pathways.
authors.affiliation: School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, United Kingdom. timwatts1984@yahoo.co.uk
authors.forename: T J
authors.initials: TJ
authors.lastname: Watts
authors.forename: R D
authors.initials: RD
authors.lastname: Handy
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology; D002121:Calcium Channel Blockers / Q000633:toxicity*; D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects*; D006461:Hemolysis / Q000187:drug effects*; D006736:Horses; D007038:Hypotonic Solutions; D066298:In Vitro Techniques; D007700:Kinetics; D009994:Osmolar Concentration; D014700:Verapamil / Q000633:toxicity*
chemical_list: D002121:Calcium Channel Blockers; D002614:Chelating Agents; D007038:Hypotonic Solutions; D004533:Egtazic Acid; D014700:Verapamil; D002118:Calcium