title: Contribution of intracellular calcium stores to an increase in cytosolic calcium concentration induced by Mannheimia haemolytica leukotoxin.
abstract: The contribution of intracellular calcium stores to Mannheimia haemolytica leukotoxin (LKT)-induced increase in cytosolic calcium concentration was studied by pharmacologically inhibiting transport of calcium across the plasma and endoplasmic reticulum membranes of bovine neutrophils exposed to LKT. Active intracellular storage of calcium by sarcoplasmic/endoplasmic reticulum calcium ATPase, influx of extracellular calcium across the plasma membrane, and release of stored calcium via inositol triphosphate receptors and ryanodine-sensitive calcium channels were inhibited using thapsigargin, lanthanum chloride, xestospongin C, and magnesium chloride, respectively. Pre-incubation with thapsigargin attenuated the increase in cytosolic calcium concentration produced by LKT, thus confirming the involvement of intracellular calcium stores. Inhibitory effects of lanthanum chloride, xestospongin C, and magnesium chloride indicated that the increase in cytosolic calcium concentration induced by LKT resulted from both influx of calcium across the plasma membrane and release of calcium from intracellular stores.
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Cudd
authors.forename: Cyril
authors.initials: C
authors.lastname: Clarke
authors.forename: Kenneth
authors.initials: K
authors.lastname: Clinkenbeard
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects*; D002417:Cattle; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D005098:Exotoxins / Q000633:toxicity*; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D007811:Lanthanum / Q000494:pharmacology; D047028:Macrocyclic Compounds; D015636:Magnesium Chloride / Q000494:pharmacology; D016978:Mannheimia haemolytica / Q000472:pathogenicity*; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D010080:Oxazoles / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D005098:Exotoxins; D047028:Macrocyclic Compounds; D010080:Oxazoles; D019837:Ryanodine Receptor Calcium Release Channel; C018579:leukotoxin; C108644:xestospongin A; D015636:Magnesium Chloride; C028521:lanthanum chloride; D019284:Thapsigargin; D007811:Lanthanum; D015544:Inositol 1,4,5-Trisphosphate