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The meaning of dopamine beta-hydroxylase in essential hypertension
Insights
Plasma dopamine beta-hydroxylase (DBH) activity is linked to hemodynamic changes in borderline hypertension but not in permanent essential hypertension, suggesting different underlying factors influence DBH levels in each condition.
Area of Science:
- Cardiovascular Physiology
- Neuroendocrinology
Background:
- Essential hypertension is a complex condition with varying underlying mechanisms.
- Dopamine beta-hydroxylase (DBH) is a key enzyme in catecholamine synthesis, potentially influencing blood pressure.
Purpose of the Study:
- To investigate the relationship between plasma DBH activity and hemodynamic parameters in untreated borderline and permanent essential hypertensive patients.
- To explore differences in DBH regulation between these hypertensive subgroups.
Main Methods:
- Measured resting plasma DBH activity and hemodynamic parameters (cardiac output, blood volumes) in 29 borderline and 27 permanent hypertensive patients, and 63 healthy controls.
- Analyzed correlations between DBH activity, blood pressure, and hemodynamic variables within each patient group.
Main Results:
- No significant difference in mean DBH levels was found between borderline and permanent hypertensive groups.
- Borderline hypertensives exhibited higher cardiac output and blood volumes compared to permanent hypertensives.
- Plasma DBH activity correlated with diastolic blood pressure and hemodynamic parameters in borderline, but not permanent, hypertensives.
Conclusions:
- Plasma DBH activity in borderline hypertension appears modulated by sympathetic activity driving hemodynamic variations.
- In permanent essential hypertension, factors other than sympathetic-driven hemodynamics likely influence plasma DBH levels.
Abstract:
1. Resting plasma dopamine beta-hydroxylase (DBH) activity and haemodynamic parameters were studied in untreated borderline (twenty-nine) and permanent (twenty-seven) essential hypertensive patients. DBH was also measured in sixty-three apparently healthy subjects. 2. Mean DBH values were not significantly different between the groups. 3. Cardiac output, cardiopulmonary blood volume and the cardiopulmonary blood volume/total blood volume ratio (CPBV/TBV) were significantly higher in borderline than in permanent hypertensive patients. 4. In borderline hypertensive patients, plasma DBH activity was directly correlated with diastolic arterial pressure and with values of cardiac output, cardiopulmonary blood volume and CPBV/TBV ratio. No such correlations could be observed in the permanent hypertensive group. 5. These results suggest that plasma DBH activities in borderline hypertension mainly depend on the sympathetic activity responsible for the haemodynamic variations. Contrariwise, plasma DBH activities in permanent essential hypertensive patients appear to reflect other factors.