ADRENALINE-THYROXIN INTERACTION IN GUINEA PIGS

Abstract

Epinephrine-thyroxin interaction in guinea pigs was studied by means of 3 tests of epinephrine effect: increased creatine excretion, increased blood sugar and decreased blood cholesterol content. In all these tests, the action of epinephrine was found to be greatly modified by thyroidectomy. The blood sugar test showed a notable diminution of sensitivity to epinephrine in these animals. On the creatine excretion of thyroidectomized animals adrenaline had an effect opposite to the normal effect. The blood cholesterol test provided indefinite results on the sensitivity of thyroidectomized guinea pigs to epinephrine. Thus the mechanism of epinephrine action appers to be different from one test to another. Thyroxin restored in all these cases the normal epinephrine effect in thyroidectomized guinea pigs. Sensitivity to epinephrine was found to be a continuous function of the thyroxin doses previously injected. The laws of this function are different from one test to another. This might indicate once more that there is no direct linkage between these 3 aspects of epinephrine action. The thyroxin doses restoring the normal sensitivity to epinephrine amounted to 0.5[mu]g/100 g. (creatine test), 0.8[mu]g./100 g. (blood sugar test), 0.5 [mu]g./100 g. (blood cholesterol test).