An estimate of the effect of acute exsanguination on catecholamine and glucoregulatory hormone concentrations in the newborn rat.

We have determined the effect of acute exsanguination on plasma concentrations of glucose, insulin, glucagon, dopamine, epinephrine and norepinephrine in neonatal Sprague-Dawley rats. This was done by comparing concentrations of these substances in aliquots of blood obtained within 10 s of the initial bleeding to those in blood obtained over the next 50 s of the blood drawing process. Concentrations of glucose and insulin showed no change between early and late samples. Glucagon concentrations showed variable responses dependent upon the age of the animal. Concentrations were unchanged at birth, but increased 22% and 58% at 1 and 6 h of age respectively. Catecholamine concentrations increased greatly (57 to 215%) between blood aliquots regardless of age at the time of sampling. These findings indicate that hormonal responses occur during the relatively brief period of blood drawing in Sprague-Dawley rats, pointing out further limitations inherent in the use of small animals for acute metabolic and hormonal studies.