Comparative Effects of Organic and Inorganic Mercury on Brain Slice Respiration and Metabolism

Abstract

Respiration and carbohydrate metabolism were measured in guinea-pig brain slices exposed to organic and inorganic mercury. Organic mercury decreased oxygen uptake and 14C02 production at consistently lower concentrations than inorganic mercury. Organic mercury also caused a striking elevation ofpyruvate and lactate at low doses where inorganic mercury had no effect on respiration or metabolism. A unique inhibition of tricarboxylic acid cycle function is suggested and might partially explain the distinctive neurotoxicity of organic nercury.

Increased free intrasynaptosomal Ca2+ by neurotoxic organometals: Distinctive mechanisms

“…Met-Hg is known to affect mitochondrial functions in situ (Verity et al, 1975;Fox et al, 1975;Cheung and Verity, 1981 ), suggesting that it can reach mitochondria. Met-Hg was less effective in elevating [Ca 2 +]i in synaptosomes, where Ca 2 + uptake into mitochondria was inhibited (rotenone + oligomycin) or where in addition ATP was depleted (rotenone + oligomycin + iodoacetic acid) beforehand.…”

“…1975; Fox et al, 1975;Yambo et al, 1985), uncoupling oxidative phosphorylation, and decreasing intracellular ATP (Cheung and Verity, 1981;Sarafian et al, 1984 ). However, nonmitochondrial processes, such as cytosolic protein synthesis, may be even more sensitive to Met-Hg (Sarafian et al, 1984;Cheung and Verity, 1985).…”

Effects of mercuric ions on isolated guinea-pig ileum

“…However, during distribution of small amounts of mercury, effects that are less pronounced than those associated with acute and massive chronic poisoning could be exerted on tissues in the body. Hg2+, in micromolar concentrations, has been shown in vitro to exert actions on isolated heart (21) and smooth-muscle contractions (22), neuromuscular (23)(24)(25)(26)(27)(28), synaptic (29,30), and sensory (31) transmission, Ca2+ release from sarcoplasmic reticulum (32), respiration and metabolism in brain tissue (33), activity of brain enzymes (34), and other activities vital for the function of excitable tissues (35,36). However, it is not qpite clear whether or how lower concentrations, <1 pM, of mercuric salts influence the physiologic functions of excitable tissues.…”

In Vitro Toxicity Testing of Environmental Agents

“…In the replating method (Figure 3c), treated cells are cultured for a period of expression time and then trypsinized and replated directly into the medium containing the selective drug. The frequency of mutation is reported to be significantly greater in the replating method than in the in situ method (Fox, 1975;, but this may differ depending on the mutagen being tested: For MMS, MNNG, UV, and X-ray irradiation, this difference was found but no difference was observed between the two procedures when EMS was used. Replating treated cells may eliminate the possibility of metabolic cooperation within colonies and thus allow for full expression of mutants.…”