Blood concentration of catecholamines and their hemodynamic effects in man

Abstract 1. 1. By using the trihydroxyindole method to measure catecholamines in both control subjects and subjects with labile hypertension, no relationship could be demonstrated between changes in blood pressure, cardiac output, total peripheral resistance and catecholamines over a 10 minute period, from day to day, or following norepinephrine infusion. 2. 2. The explanation for this lack of correlation would appear to be largely a function of the multiple factors, in addition to the infusion rate, which determine the blood level of catecholamines, and possibly the lack of sensitivity of the method. 3. 3. A consistent hemodynamic effect could be demonstrated in response to norepinephrine infusion in both the control subjects and those with labile hypertension. Although the response was similar at the initial infusion rate, increasing the rate resulted in a fall in total peripheral resistance in the labile hypertensive subjects. The explanation for this appears to be the duration of infusion rather than the dose.