Altered Ca2+ mobilization during excitation - contraction in cultured cardiac myocytes exposed to antimony.
Toraason-M; Wey-HE; Richards-DE; Mathias-PI; Krieg-E
Toxicol Appl Pharmacol 1997 Sep; 146(1):104-115
In an effort to determine whether trivalent antimony (7440360) affects intracellular free calcium concentration during excitation and contraction, the authors developed an in-vitro cardiac myocyte model that was exposed for 24 hours to potassium-antimony-tartrate (28300745) (PAT) up to concentrations of 10 microM. Even the highest concentrations had no effect on total DNA or protein content of the cultures, indicating the levels were not overtly toxic. But 5 and 10 micrometer levels did significantly reduce the spontaneous beating rates of the myocytes. At concentrations of 2 to 8 microM, PAT significantly reduced systolic intracellular calcium concentrations in a concentration dependent fashion but had no effect on the diastolic levels or on the first derivative of the transient rise. Myocytes from control cells responded to epinephrine in concentration dependent fashion with elevated systolic intracellular calcium concentrations and an increase in the rate of decay of transients. The systolic response was blunted while the decay rate was enhanced in PAT exposed myocytes. PAT exposed cells also demonstrated a reduced basal intracellular calcium concentration when depolarized by 90 mM potassium-chloride and a reduced caffeine releasable calcium pool of the sarcoplasmic reticulum. Response to ryanodine was similar for both control and PAT treated cells. The authors conclude that a nonlethal exposure to PAT reduced the availability of calcium during excitation and contraction. They suggest that a decreased influx of calcium across the sarcolemma and enhanced removal of calcium appear to be responsible.
Metabolic-study; Antimony-compounds; Cardiovascular-system-disorders; Cardiovascular-function; Electrocardiography; Cardiovascular-disease; Smelters
National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 4676 Columbia Parkway, Cincinnati, Ohio, 45226
Toxicology and Applied Pharmacology