RESUMO
The toxicity of HCN was determined first.The experimental animals were intoxicated with a HCN concentration of 1103.8?48.32 Y/L and were exposed for 4.55?2.04 minutes.The mortality rate in 24 hrs was recorded.The LDEO,sLD50,and LD99 were calculated as 844.31?/kg,172.39?/kg and 959.18?/kg respectively.Two preparations of DMAP injection were found to have preserved rather good anti-HCN potency even though they had been kept under room temperature for about one year.All the 11 dogs survigd a dose of 4 LD50 of HCN in halation poisoning when DMAP was injected intramuscularly 1 minute after exposure.Another 5 dogs inflicted with similar HCN intoxication were also all saved when intravenous DMAP injection was given at the time of respiratory arrest. The cyanide level in the blood of the dogs after inhalation of HCN was determined by spectrophotofluorometry with pyridoxal.The blood concentration after inhalation of a lethal dose of HCN was 110?26.6?/100 ml at the moment of respiratory arrest.DMAP after intramuscular injection can shift the cyanide combined with cytochrome oxidase to red blood cells to form ferrihemoglobin cyanide,and cell respiration is then restoredEventually the dogs could survive the 4 LD50 HCN intoxication.
RESUMO
The toxicity of HCN inhaled via the respiratory tract in dogs and the therapeutic effects of DMAP and AmNO2 for such form of HCN intoxication were studied. The LD50 of HCN when inhaled was 850.4?80.4?g/kg.When the dosage of 2?LD50 of HCN was given to the experimental animals, the signs of intoxication developed rapidly. Uneasiness, struggling, strident barking, and respiratory excitation were observed several seconds after the exposure. Subsequently there was spasm of the extensors and rigidity of the extremities. Finally general inhibition and paralysis ensued. Respiration and heart beat stopped 6 and 7 minutes after exposure. If DMAP (3.25 mg/kg intramuscularly) or AmNO2 (2 ampules through inhalation) was administered 15 seconds after exposure, the survival rate of the animals was 90% or 100% respectively.When the dosage of 4?LD50 of HCN was inhaled and the two drugs were administered 45 seconds after exposure, the survival rate of the animals treated with DMAP remained as high as 90% (9/10) .But the survival rate of those treated with two ampules of AmNO2 or even three ampules reduced to 20% or 40% respectively.The amount of HCN inhaled during respiratory intoxication, the problems of early diagnosis and the administration of DMAP at the site of accident were analyzed and discussed.