Uncoupling of oxidative phosphorylation in rat liver mitochondria by chloroethanols

Multiple effects of trichloroethanol on calcium handling in rat submandibular acinar cells

The effect of trichloroethanol (TCEt), the active metabolite of chloral hydrate, on the intracellular concentration of calcium ([Ca(2+)](i)) was investigated in rat submandibular glands (RSMG) acini loaded with fura-2. TCEt (1 - 10 mM) increased the [Ca(2+)](i) independently of the presence of calcium in the extracellular medium. Dichloroethanol (DCEt) and monochloroethanol (MCEt) reproduced the stimulatory effect of TCEt but at much higher concentrations (about 6 fold higher for DCEt and 20 fold higher for MCEt). TCEt mobilized an intracellular pool of calcium, which was depleted by a pretreatment with thapsigargin, an inhibitor of the sarcoplasmic and endoplasmic reticulum calcium-dependent ATPases, but not with FCCP, an uncoupler of mitochondria. TCEt 10 mM inhibited by 50% the thapsigargin-sensitive microsomal Ca(2+)-ATPase. DCEt 10 mM and MCEt 10 mM inhibited the ATPase by 20 and 10%, respectively. TCEt inhibited the increase of the [Ca(2+)](i) and the production of inositol phosphates in response to carbachol, epinephrine and substance P. TCEt inhibited the uptake of calcium mediated by the store-operated calcium channel (SOCC). ATP and Bz-ATP increased the [Ca(2+)](i) in RSMG acini and this effect was blocked by extracellular magnesium, by Coomassie blue and by oxydized ATP (oATP). TCEt potentiated the increase of the [Ca(2+)](i) and of the uptake of extracellular calcium in response to ATP and Bz-ATP. TCEt had no effect on the uptake of barium and of ethidium bromide in response to purinergic agonists. These results suggest that TCEt, at sedative concentrations, exerts various effects on the calcium regulation: (1) it mobilizes a thapsigargin-sensitive intracellular pool of calcium in RSMG acini; (2) it inhibits the uptake of calcium via the SOCC; (3) it inhibits the activation by G protein-coupled receptors of a polyphosphoinositide-specific phospholipase C. It does not interfere with the activation of the ionotropic P2X receptors. The use of chloral hydrate should be avoided in studies exploring the in vivo responses to sialagogues.

Acute ethylene chlorohydrin poisoning: experience of a poison control center

BACKGROUND

Ethylene chlorohydrin (CAS 107-07-3), a chemical once used in hastening grape vine sprouting in Taiwan, has caused severe toxicity upon acute exposure. Although such use of ethylene chlorohydrin is now prohibited in Taiwan, poisoning still occurs following its illegal use. Since data concerning human ethylene chlorohydrin poisoning remain rare, we report our experience in treating acute ethylene chlorohydrin-poisoned patients.

METHODS

A retrospective analysis was conducted to evaluate patients with ethylene chlorohydrin poisoning reported to Taiwan Poison Control Center during 1985-1998.

RESULTS

Seventeen patients with ethylene chlorohydrin poisoning were identified. There were 11 male and 6 female patients, ranging in age from 2 to 70 years (median 53 years). The intent of exposure was suicide in 5, accident in 9, and occupational exposure in 3 patients. Oral ingestion was the most common route of exposure (14 patients). Seven out of the 17 patients died within 24 hours due to metabolic acidosis and respiratory failure. Ethanol therapy, used in 2 patients, had no apparent benefit. Moderate or mild poisoning was characterized by gastrointestinal effects only and an uneventful recovery.

CONCLUSIONS

Ethylene chlorohydrin can result in severe metabolic acidosis, respiratory failure, coma, and death after acute exposure.

Prophylaxis and reversal of ifosfamide encephalopathy with methylene-blue

The antineoplastic ifosfamide produces dose-dependent signs of neurotoxicity. After ifosfamide overdose in a patient, we found excessive urinary excretion of glutaric acid and sarcosine, which is compatible with glutaric aciduria type II, a defect in mitochondrial fatty acid oxidation that results from defective electron transfer to flavoproteins. We therefore used the electron-accepting drug methylene-blue as an antidote for ifosfamide encephalopathy. In one patient, ifosfamide neurotoxicity was rapidly reversed by methylene-blue 50 mg intravenously. In another patient with previous episodes of ifosfamide encephalopathy, methylene-blue was administered orally prophylactically. No symptoms of neurotoxicity were noted.