Estimation of systemic catecholamine levels in the frog, using the technic of radio-enzymatic assay]

We have developed a radio-enzymatic assay for systemic catecholamines in the frog. Such are its specificity and sensibility that adrenaline and noradrenaline may be measured in 50 microliter of plasma samples, the withdrawal of which strongly influenced the results. The smaller values were obtained in plasma withdrawn from canulated animals. In this case, adrenaline was the major catecholamine in the plasma: 190 +/- 55 ng/100 ml versus 35 +/- 18 ng/100 ml for noradrenaline.