Quantification of plasma cortisol levels in ascorbic acid studies using guinea pigs implanted with ACTH pellets.
A method is described that permits multiple blood collections from unanesthetized, unrestrained guinea pigs with minimal disruption to the animal, as verified by plasma cortisol (PC) levels. Blood (100-200 microliters) was collected from the lateral metatarsal vein using a vacuum-assisted method. Using this method, the effect of subcutaneously-implanted slow-releasing ACTH versus placebo pellets on PC levels was determined. A small, but significant, increase in PC concentration occurred in the control group, reflecting the stress of handling and the implant procedure. In contrast, the peak concentration of PC after implantation of a pellet containing ACTH was 20 times the starting level and occurred within 4 hr. However, the PC level was not correlated with the content of ACTH in the pellet because a similar level was achieved with 0.125 or 8 mg/pellet. A decline in Pc to pre-treatment levels occurred within 24 to 48 hr. The results indicate that administration of ACTH by pellet, although intended to achieve a sustained elevation in PC level, is not suitable for maintaining elevated PC levels.
Kipp
D E
DE
Department of Dietetics and Nutrition, University of Kansas Medical Center, Kansas City 66103.
Fox
L M
LM
D000324:Adrenocorticotropic Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D001800:Blood Specimen Collection / Q000379:methods / Q000662:veterinary*; D004343:Drug Implants; D006168:Guinea Pigs / Q000378:metabolism*; D006854:Hydrocortisone / Q000097:blood*; D008297:Male; D011897:Random Allocation
D004343:Drug Implants; D000324:Adrenocorticotropic Hormone; D001205:Ascorbic Acid; D006854:Hydrocortisone