Effect of single and repeated carbon monoxide intoxications on urinary catecholamine excretion in rats

In preliminary experiments it had been shown that the total catecholamines in the urine of rats collected during 5 hrs after stimulation of diuresis with 50 ml tap water/kg body weight per os were not changed significantly following a 3-week training in individual metabolic cages, a short pressing of the animals against the laboratory table, a single i. p. injection of 2 ml sodium chloride solution (145 mmol/l)/kg body weight, or a single s. c. injection of 40 ml air per animal. The excretion was increased after puncture of the retroorbital plexus and after exposure to cold (+5 degrees C) during the 5 hrs. Carbon monoxide poisoning produces an inhibition of diuresis. Therefore, to study the effect of carbon monoxide intoxications on urinary catecholamine excretion we administered 25 ml tap water/kg additionally. Single s. c. injection of 7.2 mmol CO/kg body weight (53% COHb) induced a significant increase of urinary catecholamines. Due to repeated injections of the same CO dose a gradual disappearance of this effect was seen. After 4 weeks the differences to controls are negligible.