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Calcium antagonists and ACE inhibitors. Effect on endothelium and vascular smooth muscle
1Department of Medicine, University Hospital, Bern, Switzerland.
Insights
Cardiovascular drugs like ACE inhibitors and calcium antagonists protect blood vessels. ACE inhibitors boost bradykinin, increasing nitric oxide and prostacyclin, while calcium antagonists improve relaxation and inhibit smooth muscle proliferation.
Area of Science:
- Cardiovascular Pharmacology
- Endothelial Biology
- Vascular Smooth Muscle Physiology
Background:
- Endothelial dysfunction is an early indicator of cardiovascular disease.
- Vascular smooth muscle cell migration and proliferation contribute to disease progression.
- Cardiovascular drugs, including calcium antagonists and ACE inhibitors, are vital for disease management.
Purpose of the Study:
- To elucidate the vascular protective effects of calcium antagonists and ACE inhibitors.
- To understand the mechanisms by which these drugs influence endothelial and vascular smooth muscle function.
- To highlight the role of nitric oxide, prostacyclin, and bradykinin in mediating drug effects.
Main Methods:
- Review of existing literature on cardiovascular drug mechanisms.
- Analysis of the effects of ACE inhibitors on the renin-angiotensin-aldosterone system and bradykinin pathways.
- Examination of calcium antagonists' impact on endothelium-dependent relaxation and smooth muscle contraction, including endothelin-1 and growth factor effects.
Main Results:
- ACE inhibitors increase bradykinin, leading to enhanced nitric oxide and prostacyclin production, promoting vasodilation and inhibiting platelet function.
- Nitric oxide derived from ACE inhibitor action may possess antiproliferative effects on vascular smooth muscle cells.
- Calcium antagonists facilitate endothelium-dependent relaxation and counteract endothelin-1-induced contractions, with potential antiproliferative effects against platelet-derived growth factor.
Conclusions:
- ACE inhibitors offer vascular protection through bradykinin-mediated nitric oxide and prostacyclin release.
- Calcium antagonists contribute to vascular health by enhancing relaxation and inhibiting smooth muscle proliferation, particularly relevant in conditions with endothelial dysfunction.
Abstract:
The effects of cardiovascular drugs on endothelium and vascular smooth muscle function are important for the prevention of cardiovascular disease. Changes in endothelial function are an early event in most forms of cardiovascular disease and, later in the disease process, vascular smooth muscle cells are functionally altered and begin to migrate to and proliferate in the intima. Calcium antagonists and angiotensin converting enzyme (ACE) inhibitors are widely used in patients with cardiovascular disease and are thought to have vascular protective effects. ACE, an enzyme located in the endothelial cell membrane, activates angiotensin I and angiotensin II, and deactivates bradykinin. Bradykinin activates endothelial bradykinin (B2) receptors, which results in the formation of nitric oxide and prostacyclin. Hence, ACE inhibitors not only prevent the formation of angiotensin II, but also increase the local levels of bradykinin and in turn nitric oxide and prostacyclin. These compounds are vasodilators and potent inhibitors of platelet function, and therefore may mediate important protective effects of ACE inhibitors. Furthermore, nitric oxide may have antiproliferative effects in vascular smooth muscle cells. Calcium antagonists do not appear to affect the release of endothelium-derived relaxing factors or any other endothelial product. However, they facilitate endothelium-dependent relaxation and reduce the contracting effects of endothelin-1 at the level of smooth muscle. Indeed, in some blood vessels, e.g. the large coronary arteries and the human forearm circulation, verapamil and nifedipine antagonise endothelin-induced contractions. In addition, calcium antagonists inhibit the effects of platelet-derived growth factor and may have antiproliferative effects in vascular smooth muscle cells. In conditions involving progressive dysfunction of the endothelium, vascular deposition of platelets increases the local levels of platelet-derived growth factor, and the antiproliferative effects of calcium antagonists may thus be particularly important.