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Plasma noradrenaline concentration and alpha-adrenoceptor-mediated vasoconstriction in normotensive and hypertensive
Insights
In essential hypertension, plasma noradrenaline levels were similar between patients and controls but correlated with blood pressure. This suggests plasma noradrenaline may indicate sympathetic activity and vascular resistance in hypertensive individuals.
Area of Science:
- Cardiovascular Physiology
- Clinical Pharmacology
- Hypertension Research
Background:
- Essential hypertension is a complex condition with multifactorial causes.
- Sympathetic nervous system activity plays a role in blood pressure regulation.
- Alpha-adrenoceptors mediate vascular resistance and are targets for blood pressure control.
Purpose of the Study:
- To investigate the relationship between plasma noradrenaline concentrations and blood pressure in patients with essential hypertension.
- To assess the alpha-adrenoceptor-mediated component of vascular resistance in hypertensive and normotensive subjects.
- To determine if plasma noradrenaline serves as a marker for sympathetic activity and vascular resistance in hypertension.
Main Methods:
- Measurement of plasma noradrenaline concentrations and blood pressure in 45 hypertensive and 34 normotensive subjects.
- Intra-arterial infusion of phentolamine to assess alpha-adrenoceptor-mediated vasodilation in a subset of participants.
- Correlation analysis to examine relationships between variables.
Main Results:
- Plasma noradrenaline levels were similar between hypertensive and normotensive groups.
- In hypertensive patients, plasma noradrenaline correlated significantly with blood pressure.
- The alpha-adrenoceptor-mediated vasodilation response to phentolamine correlated with plasma noradrenaline and blood pressure in hypertensive patients.
Conclusions:
- Plasma noradrenaline may serve as a useful marker for sympathetic nervous system activity in essential hypertension.
- The alpha-adrenoceptor-mediated component of vascular resistance in hypertensive patients is related to plasma noradrenaline levels.
- These findings contribute to understanding the pathophysiology of essential hypertension and potential therapeutic targets.
Abstract:
1. Plasma noradrenaline concentrations and blood pressure were measured in 45 patients with essential hypertension and 34 matched normotensive subjects. Plasma noradrenaline was similar in both groups, but in the hypertensive patients plasma noradrenaline correlated with blood pressure. 2. The increase in forearm flow in response to an intra-arterial infusion of phentolamine was determined in 12 of the hypertensive and 14 of the normotensive subjects to assess the alpha-adrenoceptor-mediated component of vascular resistance. Although the dilator response to phentolamine was similar in both groups, in the hypertensive patients it was correlated with the control plasma noradrenaline (r = 0.83, P less than 0.01) as well as the height of mean blood pressure (r = 0.73, P less than 0.01). 3. These results suggest that in hypertensive patients plasma noradrenaline can be a marker for both sympathetic activity and the alpha-adrenoceptor-mediated component of vascular resistance.