Characterization of in vivo effects of dilithium carbamyl phosphate on dog hemoglobin structure and function.

The effect of oral administration of dilithium carbamyl phosphate on adult beagle dogs is dose related. The levels of carbamylation as mol valine hydantoin/mol hemoglobin tetramer reaches a plateau of 0.3-0.38 with daily doses of 100 mg/kg body weight. Related changes in oxygen binding by whole blood and hemoglobin amount to a 5-15% left shift in oxygen isotherms. After discontinuing the administration of carbamyl phosphate, the disappearance of modified hemoglobin with a return to normal oxygen binding values follows the gradual replacement of old cells by new cells in the circulation. When the level of in vivo carbamylation in dog blood is greater than 0.16, it is similar to the levels of in vitro carbamylation of hemoglobin SS which result in the interference with sickling of erythrocytes at low levelsof oxygen.