Anesthetic agents and sympatho-adrenal response to hemorrhage in the rat

The sympatho-adrenal activity as reflected in plasma catecholamine levels was studied in rats subjected to a standardized hemorrhage. A comparison was performed between awake rats and rats anesthetized with diethylether, enflurane, barbiturate or ketamine. As expected diethylether increased sympathoadrenal activity. Enflurane induction increased adrenaline and decreased noradrenaline levels. Upon hemorrhage the sympatho-adrenal activity was depressed compared to the awake state. Barbiturate anesthesia depressed sympatho-adrenal activity. Ketamine increased noradrenaline levels and a relative hypertension was noticed during bleeding. The results focus attention on important differences in sympatho-adrenal activity between awake rats and rats anesthetized with different agents.