Human Sympathetic Activity Research Articles

Circulating catecholamines, plasma renin and dopamine-beta-hydroxylase activity with postural stress

Changes in human plasma renin activity, catecholamines and dopamine-beta-hydroxylase activity as a result of head-up tilt and low salt diet are reported. Both salt restriction and head-up tilt increased plasma renin activity and these responses appeared to summate. Head-up tilt increased plasma norepinephrine and epinephrine, but sodium restriction was without effect. Neither stimulus produced significant alterations in plasma dopamine-beta-hydroxylase catalytic activity. No correlation between dopamine-beta-hydroxylase activity and either circulating catecholamine was observed. These results indicate that plasma dopamine-beta-hydroxylase catalytic activity is not a good indicator of acute relatively mild changes in sympathetic activity in humans.