Distribution of Injected Adrenaline and Noradrenaline in Plasma and Muscle of the Rat

¹ From the Department of Zoology, Cornell University, Ithaca, New York

The Weil-Malherbe and Bone fluorimetric method of determining adrenaline and noradrenaline was adapted for measuring these hormones in small samples of blood plasma and muscle in the rat. The endogenous levels of adrenaline and noradrenaline, respectively, for rat plasma are 6.7 ± 0.08 and 17.7 ± 0.06 µg/l.; for the rectus femoris muscle 0.020 ± 0.002 and 0.149 ± 0.011 µg/gm tissue. Ten micrograms l-adrenaline and 20 µg d,l-noradrenaline/100 gm body weight were injected intraperitoneally, and plasma and muscle samples analyzed for these hormones at timed intervals thereafter. The injection of adrenaline effects a prompt increase in both plasma and muscle noradrenaline; a significant increase in adrenaline level was found 6 minutes after injection in the plasma, and at 60 minutes in the muscle tissue. A return to initial levels occurred at approximately 10 minutes and 90 minutes, respectively. The injection of noradrenaline resulted in an immediate increase in the plasma and muscle levels of this hormone; coincidently the adrenaline levels remained relatively unchanged.