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Treatment of hypertension with calcium antagonists. Review
Insights
Calcium channel blockers, like verapamil and nifedipine, effectively lower blood pressure by relaxing blood vessels and reducing heart workload. They show promise in treating various hypertensive conditions by targeting intracellular calcium levels.
Area of Science:
- Cardiovascular Pharmacology
- Hypertension Research
Background:
- Calcium channel blockers (CCBs) selectively impact the cardiovascular system.
- They decrease cardiac energy demands and vascular smooth muscle tone, enhancing systemic blood flow.
Purpose of the Study:
- To review the advantages and limitations of verapamil and nifedipine in hypertension management.
- To examine their hemodynamic effects and therapeutic applications in hypertensive emergencies and related conditions.
Main Methods:
- Review of clinical experience with verapamil and nifedipine in hypertensive patients.
- Analysis of acute hemodynamic effects in subjects with hypertension.
- Examination of therapeutic uses in specific hypertensive conditions.
Main Results:
- CCBs reduce blood pressure by causing vasodilatation in systemic and pulmonary systems.
- Verapamil and nifedipine are the primary CCBs used clinically for hypertension.
- Nifedipine's effects suggest intracellular calcium's role in vasoconstriction and hypertension.
Conclusions:
- CCBs are valuable in managing elevated blood pressure.
- Altered intracellular calcium handling may be a key factor in maintaining human hypertension.
- Further research into calcium's role in hypertension is warranted.
Abstract:
Calcium channel blockers have a selective action on the cardiovascular system. They reduce the energy requirement of the heart, reduce vascular smooth muscle tone, and increase systemic blood flow. Vasodilatation occurs in both the systemic and the pulmonary systems to an extent proportional to the baseline level of vascular resistance, and results in reduction of blood pressure when it is elevated. Thus, these blockers are useful in patients with high blood pressure. Clinical experience of calcium channel blockers in hypertension is so far confined almost exclusively to verapamil and nifedipine. This article reviews the advantages and limitations of these two compounds, their acute hemodynamic effects in hypertensive subjects, and their use in the treatment of hypertensive emergencies, hypertensive encephalopathy, and pheochromocytoma, and as ventricular afterload reducing agents in hypertensive left ventricular failure. Similarities in the effects of nifedipine on systemic and pulmonary vascular tone are presented as evidence that altered intracellular Ca++ concentration is involved in the vasoconstriction seen in both systems in systemic high blood pressure. They also provide support for the hypothesis that inappropriate Ca++ handling may be involved in maintaining elevated blood pressure in human hypertension.