Objective: Oral administration of L-tryptophan with a toxic effect, produces acute bovine pulmonary edema and emphysema. In rumen tryptophan is metabolized to indole acetic acid and then by lactobacilli it will be changed to 3-methyl indole.
Design: Interventional study.
Animals: 4 calves (one calf tryptophan, 3 calves 3M1) and 2 calves for controls.
Procedure: Experimentally, 0.64 gr/kg BW of tryptophan tablets were orally administrated to one male calf of 6 month of age. and 3 calves, were received 100, 150 mg/kg of 3M1 orally respectively.
Statistical analysis: Descriptive statistics.
Results: After 4 days all calves were affected by ARDS dyspnea with oral and nasal discharge and tachypnea.
Conclusion: Pathophysiologic mechanism of edema is related to increasing endothelial and alveolar permeability due to the injury of endothelial cells, type I pneumonocyte and clara cells. The important role is cytochrome dependent-mixed function oxidase (MFO) activity and delivery of methylen immine a kind of free radical. The nucleophilic material like GSH, L-cysteine and Nacetyl L cysteine. prevent covalent combination of reactive metabolite of 3Ml to microsomal proteins. Some other substances like Phenobarbital which induces cytochrome P-450, would be able to evacuate 3M1 from plasma and therefore prevents the pulmonary tissue from injury. J. Fac. Vet. Med. Univ. Tehran. 57, 1: 93-95, 2002.