Changes of plasma dopamine-beta-hydroxylase activity and other plasma constituents during the cold pressor test

The effect of the cold pressor test on plasma DBH activity in ten healthy human subjects was investigated. Parallel changes of other plasma constituents were ascertained as well. Plasma DBH activity rose by over ten per cent in six of the sen subjects and declined by 14 per cent or more in two subjects; the correlations of altertions in DBH activity with changes of high molecular weight plasma constituents were high (r=0.565 to 0.902); correlations with blood urea nitrogen and plasma glucose were low (r=0.002 to 0.248). The results suggest that factors other than neuronal DBH release may be important in alterations of plasma DBH activity following $\text{acute}$ stresses produced by the cold pressor test in man.