Comparison of aqueous porcine ACTH with synthetic ACTH in adrenal stimulation tests of the female dog.

The adrenocortical (plasma corticosteroid) responses in female dogs given porcine ACTH in gelatin (1-39 amino acid sequence) and synthetic ACTH (1-24 amino acid sequence) were compared. Sixteen dogs were used. Each dog underwent 4 different ACTH stimulation studies, these being done with a 4- to 8-week interval. The studies in each dog included injections of 2 doses of porcine ACTH--2.2 IU and 4.4 IU/kg of body weight--and of 2 doses of synthetic ACTH--0.25 mg/dog and 0.50 mg/dog. The dogs were arbitrarily allotted to 4 groups, each group being subjected to a given sequence of stimulation studies. The purpose in this project was to determine whether the established methods for synthetic and porcine ACTH stimulation tests had similar results. Statistical analysis of the 4 stimulation methods revealed no significance (P greater than 0.05) in the resting or poststimulation plasma corticosteroid concentrations. Thus, it was concluded that either recommended method using ACTH (porcine ACTH at 2.2 IU/kg or synthetic ACTH at 0.25 mg/dog) causes maximal secretion of adrenocortical reserve. Either ACTH preparation, using the established method, can be used interchangeably.