Lack of correlation between serum dopamine-beta-hydroxylase activity and blood pressure in middle-aged men

Biphasic effects of smoking on human serum dopamine-beta-hydroxylase activity

To investigate the chronic effects of smoking on sympathetic nerve activity, serum dopamine-beta-hydroxylase (DBH) activity was determined in 119 male non-smokers and 183 age-matched male smokers. The smokers were classified into 3 groups: 51 light smokers (1-19 cigarettes/day), 76 moderate smokers (20 cigarettes/day), and 56 heavy smokers (more than 20 cigarettes/day). The light smokers had the highest mean DBH activity, and the heavy smokers had the lowest mean DBH activity in the 4 groups. These results suggest that light smoking stimulates the sympathetic nervous system, but that heavy smoking depresses the system. These biphasic changes in DBH activity are similar to the pharmacological effects of nicotine on the peripheral sympathetic nervous system.

Renal and systemic hemodynamics in sustained essential hypertension

Cardiac output (CO), renal blood flow (RBF), calf blood flow (CBF), and hepatic blood flow (HBF), glomerular filtration rate (GFR), and dopamine beta hydroxylase (D beta H) activity were studied in 198 men (67 normotensive controls and 131 hypertensive patients) of the same age with sustained uncomplicated essential hypertension. In the hypertensive men, the RBF and the RBF/CO ratio were significantly decreased (p less than 0.001). The RBF and RBF/CO ratio were negatively correlated with age (p less than 0.01), blood pressure (p less than 0.01), and D beta H activity (p less than 0.01). None of these relationships were observed with CBF and HBF. The observed decreases in RBF and the RBF/CO ratio in hypertensive men were reversed after administration of clonidine and alpha-methyldopa (p less than 0.01), but not after administration of propranolol. The study provides evidence that the reduction of renal perfusion in essential hypertension is partly reversible and related to an abnormality in the adrenergic system control.