title: Protection of cells against membrane damage by haemolytic agents: divalent cations and protons act at the extracellular side of the plasma membrane.
abstract: The protective effect of Ca2+, Zn2+ and H+ against membrane damage induced by different haemolytic agents has been studied by measuring monovalent cation leakage and haemolysis of erythrocytes, and phosphoryl[3H]choline and adenine nucleotide leakage from Lettre cells prelabelled with [3H]choline. The protective effect of Ca2+ and Zn2+ on erythrocytes damaged by Staphylococcus aureus alpha-toxin, Sendai virus or melittin is unaffected by the addition of A23187, even though this ionophore greatly increases the uptake of 45Ca2+ or 65Zn2+. The same result has been found for the protective effect of Zn2+ on Lettre cells damaged by S. aureus alpha-toxin, Sendai virus, melittin or Triton X-100. Leakage of phosphoryl[3H]choline from prelabelled Lettre cells is inhibited if extracellular pH is lowered; lowering the intracellular pH without affecting the extracellular pH, affords little protection. It is concluded that Ca2+, Zn2+ and H+ protect cells against membrane damage induced by haemolytic agents by an action at the extracellular side of the plasma membrane.
authors.affiliation: Department of Biochemistry, St George's Hospital Medical School, London, U.K.
authors.forename: C L
authors.initials: CL
authors.lastname: Bashford
authors.forename: L
authors.initials: L
authors.lastname: Rodrigues
authors.forename: C A
authors.initials: CA
authors.lastname: Pasternak
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000097:blood / Q000494:pharmacology*; D002286:Carcinoma, Ehrlich Tumor / Q000648:ultrastructure; D002413:Cations, Divalent; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure*; D002463:Cell Membrane Permeability / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000648:ultrastructure*; D006460:Hemolysin Proteins; D006801:Humans; D007700:Kinetics; D008555:Melitten / Q000494:pharmacology; D051379:Mice; D010222:Parainfluenza Virus 1, Human; D013211:Staphylococcus aureus; D015032:Zinc / Q000097:blood / Q000494:pharmacology*
chemical_list: D001427:Bacterial Toxins; D002413:Cations, Divalent; D006460:Hemolysin Proteins; C021091:staphylococcal alpha-toxin; D008555:Melitten; D000001:Calcimycin; D015032:Zinc; D002118:Calcium