Juvenile alligators became completely immobile 5 min after immersion in ice
water and remained in rigor for 40 min when removed from the water, but re
covered righting responses within 5 min after immersion in tepid water. A b
lood sample was taken prior to the treatment, at 1 hr post-treatment and at
24 and 48 hr after recovery. Plasma norepinephrine, epinephrine, and dopam
ine were measured using high-pressure liquid chromatography (HPLC), and cor
ticosterone by radioimmunoassay (RIA). Plasma ions, phosphate, and lipids w
ere measured on an autoanalyzer and blood smears were taken for differentia
l white cell counts. Norepinephrine and epinephrine were close to 4 ng/ml a
t the initial bleed: at I hr post-treatment epinephrine increased to 7 ng/m
l and norepinephrine rose to over 40 ng/ml. Mean plasma dopamine was less t
han 0.7 ng/ml at the initial bleed and post-treatment means were as high as
10 ng/ml, but values were too variable to show statistical significance. P
lasma corticosterone rose significantly at 1 hr and returned to levels not
significantly different from initial at 24 and 48 hr. Despite the massive i
ncrease in catecholamines, plasma glucose did not change throughout the exp
eriment. Plasma triglyceride increased significantly at 24 and 48 hr and pl
asma cholesterol decreased significantly at 24 and 48 hr. All other plasma
components with the exception of calcium and sodium showed changes. Both ly
mphocytes and heterophils increased at 48 hr and other white cell types sho
wed a decrease. Overall, these results suggest that short-term cold exposur
e is less stressful to alligators than simple restraint. J. Exp. Zool. 283:
566-572, (C) 1999. Wiley-Liss, Inc.