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Hemodynamic and antihypertensive treatment responses with calcium antagonists
Insights
Calcium antagonists effectively lower blood pressure by promoting vasodilation. Patient age influences response, with older individuals benefiting more due to blunted counterregulatory reflexes.
Area of Science:
- Pharmacology
- Cardiovascular Medicine
- Hypertension Research
Background:
- Calcium antagonists induce vasodilation and lower blood pressure.
- Initial responses involve sympathetic and renin-angiotensin system activation.
- Chronic treatment leads to subsidence of these counterregulatory effects.
Purpose of the Study:
- To investigate the influence of age on the antihypertensive response to calcium antagonists.
- To explore the role of baroreflex and counterregulatory systems in hypertension management.
- To examine the effect of antihypertensive treatments on calcium concentration in platelets.
Main Methods:
- Analysis of baroreflex-mediated responses during calcium antagonist treatment.
- Comparison of treatment outcomes in older versus younger hypertensive patients.
- Measurement of free cytosolic calcium concentration in platelets before and after treatment.
Main Results:
- Older patients exhibit a greater blood pressure reduction with calcium antagonists compared to younger patients.
- Younger patients show a better response to beta-blockers.
- Antihypertensive treatment normalizes elevated platelet calcium concentration and calcium influx-dependent vasoconstriction.
Conclusions:
- Age-related differences in baroreflex sensitivity significantly impact calcium antagonist efficacy.
- Individual patient responsiveness of counterregulatory systems is crucial for antihypertensive outcomes.
- Platelet calcium concentration may serve as a biomarker for vascular smooth muscle calcium levels and treatment response.
Abstract:
Calcium antagonists induce vasodilation and a consequent fall in blood pressure that initially is associated with baroreflex-mediated stimulation of the sympathetic nervous and renin-angiotensin system, resulting in increased heart rate and cardiac output. During chronic treatment, baroreflex-mediated stimulatory effects subside, probably because of a resetting of baroreflexes or inhibition of neuronal noradrenaline release. Ultimately, the antihypertensive response is codetermined by the responsiveness of these counterregulatory systems in the individual patient. In older patients who have blunted baroreflex and beta-adrenoceptor-mediated functions, a greater fall in blood pressure results as compared with younger patients in whom counterregulatory reflexes are more vivid. Therefore, older patients respond particularly well to calcium antagonists, whereas younger patients respond better to beta-blockers. In patients with essential hypertension, free cytosolic calcium concentration in platelets is elevated and calcium influx-dependent vasoconstriction is enhanced. Antihypertensive treatment with calcium antagonists and beta-blockers results in a normalization of both calcium influx-dependent vasoconstriction as well as free calcium concentration in platelets. Free cytosolic calcium concentration in platelets may reflect free calcium concentration in vascular smooth muscle cells, its reduction leading to vasodilation and antihypertensive response.