title: Effect of calcium on the hemolytic activity of Stichodactyla helianthus toxin sticholysin II on human erythrocytes.
abstract: Sticholysin II (St II) is a toxin from the sea anemona Stichodactyla helianthus that produces erythrocytes lysis at low concentration and its activity depends on the presence of calcium. Calcium may act modifying toxin interaction with erythrocyte membranes or activating cellular processes which may result in a modified St II lytic action. In this study we are reporting that, in the presence of external K(+), extracellular calcium decreased St II activity on erythrocytes. On the other hand an increase of intracellular calcium promotes Sty II lytic activity. The effect of intracellular calcium was specifically studied in relation to membrane lipid translocation elicited by scramblases and how this action influence St II lytic activity on erythrocytes. We used 0.5 mmol/L calcium and 10 mmol/L A23187, as calcium ionophore, for scramblases activation and found increased St II activity associated to increase of intracellular calcium. N-ethyl maleimide (activator) and 4,4'-diisothiocyanatostilbene-2,2'-disulfonate (inhibitor) were used as scramblases modulators in the assays which produced an increase and a decrease of the calcium effect, respectively. Results reported suggest an improved St II membrane pore-forming capacity promoted by intracellular calcium associated to membrane phospholipids translocation.
authors: Departamento de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Chile.
authors: Gloria
authors: G
authors: Celedón
authors: Gustavo
authors: G
authors: González
authors: Eduardo
authors: E
authors: Lissi
authors: Tania
authors: T
authors: Cerda
authors: Diana
authors: D
authors: Martinez
authors: Carmen
authors: C
authors: Soto
authors: Mario
authors: M
authors: Pupo
authors: Fabiola
authors: F
authors: Pazos
authors: Maria E
authors: ME
authors: Lanio
authors: Carlos
authors: C
authors: Alvarez
mesh_terms: D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D002942:Circular Dichroism; D003064:Cnidarian Venoms / Q000633:toxicity*; D004910:Erythrocyte Membrane / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects*; D005033:Ethylmaleimide / Q000494:pharmacology; D006461:Hemolysis / Q000187:drug effects*; D006801:Humans; D008563:Membrane Lipids / Q000097:blood; D009995:Osmosis / Q000187:drug effects; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D003064:Cnidarian Venoms; D008563:Membrane Lipids; C404794:sticholysin II; D000001:Calcimycin; D005033:Ethylmaleimide; D002118:Calcium