Effect of Epinephrine, Antihistaminics and Adrenergic Blockade on Egg White Edema in Adrenal Insufficient Rats

SENSITIVITY OF THE RAT TO INCREASING DOSES OF DEXTRAN

Increasing doses of dextran, a commercial 6% solution, were injected intravenously into both intact and adrenalectomized rats to evaluate the dose–response relationship. The minimum dose capable of producing an edema with 100% incidence was approximately 30 mg/kg in intact and only 4 mg/kg in adrenalectomized rats. Lower doses produced responses of decreasing intensity and incidence with a longer period of onset. Conversely, higher doses resulted in a shorter period of onset and a more intense reaction until a toxic dose was reached, beyond which cyanosis and shock appeared. Adrenalectomized rats reacted similarly to intact ones except that their response occurred at a lower dose range; they could not withstand the toxic effect of higher doses and died of circulatory failure. The fact reported by other workers that the edema is more intense and appears more rapidly after intravenous injection of minute rather than large quantities of dextran was not confirmed; the existence of a "critical dose" that does not produce any edema was not substantiated.