Effect of heavy metals and lanthanum on sugar transport in isolated guinea pig left atria.
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.
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
D008670:Metals; D008757:Methylglucosides; D003035:Cobalt; D008345:Manganese; D010042:Ouabain; D007811:Lanthanum; D009532:Nickel