[Plasma catecholamine content in hypertensive subjects and spontaneously hypertensive rats using radioenzymatic assay...

The present experiments were undertaken to determine the plasma catecholamine content in normotensive, slightly hypertensive humans and spontaneously hypertensive rats using radioenzymatic assay. In addition, attempts were made to compare radioenzymatic assay with a fluorometric technique, using high performance liquid chromatography with respect to human plasma catecholamine content. Human plasma catecholamine content in normotensive subjects at rest was 250 +/- 61 pg/ml (mean +/- S.E.) for norepinephrine and 37 +/- 22 for epinephrine. Immediately after treadmill exercise, human plasma norepinephrine content significantly increased. In 14 patients with mild essential hypertension, plasma norepinephrine was 460 +2- 128 pg/ml with the subject in a supine position and 1030 +/- 151 in the case of treadmill exercise. Thus, there was a statistically significant difference. With regard to plasma catecholamine content in spontaneously hypertensive rats, the norepinephrine content was 816 pg/ml, epinephrine was 209 pg/ml and dopamine was 505 pg/ml, on an average. After comparing this method with the fluorometric technique using high performance liquid chromatography, we confirmed that the former requires much smaller sizes of samples and has much the same sensitivity as the latter.