title: Effect of heavy metals and lanthanum on sugar transport in isolated guinea pig left atria.
abstract: The effect of heavy metals on sugar transport in fully resting guinea pig left atria was studied by measuring the tissue-medium distribution of 3-methylglucose. Basal sugar transport was increased significantly by all heavy metals tested (Co2+, Ni2+, Zn2+, Mn2+ (2 mM) and by La3+ (0.05 mM) but 1 mM La3+ had no effect. The stimulation of sugar transport by insulin, hyperosmolarity, K+-free medium, or 10(-5) M ouabain was strongly antagonized by Ni2+, Zn2+, and La3+ but was unaffected by Co2+ and Mn2+. The heavy metals did not affect intracellular Na2+ and K+, whether in the basal state or when the Na+ pump was depressed by ouabain or K+-free medium. The data suggest that Ca2+ antagonistic ions may affect sugar transport both by inhibiting Ca2+ influx and by competing with Ca2+ for specific binding sites presumably involved in the regulation of sugar transport.
mesh_terms: D000818:Animals; D050260:Carbohydrate Metabolism; D003035:Cobalt / Q000494:pharmacology; D006168:Guinea Pigs; D007811:Lanthanum / Q000494:pharmacology*; D008297:Male; D008345:Manganese / Q000494:pharmacology; D008670:Metals / Q000494:pharmacology*; D008757:Methylglucosides / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D009532:Nickel / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology
chemical_list: D008670:Metals; D008757:Methylglucosides; D003035:Cobalt; D008345:Manganese; D010042:Ouabain; D007811:Lanthanum; D009532:Nickel