Influence of mercury on uptake of [3H]dopamine and [3H]norepinephrine by rat brain synaptosomes.
Mercuric compounds have been shown to alter several membrane-bound enzymes and associated receptor activities. The present studies were initiated to investigate the in vitro effects of mercuric chloride (HgCl2) and methylmercury chloride (CH3HgCl) on the uptake of [3H]dopamine (3HDA), [3H]norepinephrine (3HNE), and Na+, K+-ATPase in rat brain synaptosomes. Brain synaptosomes were prepared by the ficoll-sucrose gradient method from normal, adult male Sprague-Dawley rats, weighing approx. 200 g. The effect of mercury on Na+, K+-ATPase was determined by using a coupled enzymatic method. Uptake of DA and NE by brain synaptosomes was determined by filtration in the presence and absence of 0-30 microM HgCl2 and 0-100 microM CH3HgCl. A parallel inhibition in the synaptosomal uptake of 3HDA and 3HNE, and the activity of the synaptosomal membrane Na+, K+-ATPase, was observed in both mercuric chloride and methylmercury treatments. The mercury compounds also significantly inhibited the mitochondrial ATPase (Mg2+-oligomycin-sensitive ATPase). The inhibitory influences of the toxins were concentration-dependent. The results suggest that the mercury compound mediated decrease in DA and NE uptake in brain synaptosomes may be related to the inhibition of Na+, K+-ATPase by the same toxins.
D000818:Animals; D001921:Brain / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008628:Mercury / Q000633:toxicity*; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013574:Synaptosomes / Q000378:metabolism*; D014316:Tritium
D014316:Tritium; D000254:Sodium-Potassium-Exchanging ATPase; D008628:Mercury; D004298:Dopamine; D009638:Norepinephrine