Vasodilators arterial

Vasodilators Arterial Arterial and venous Hydralazine Nitroprusside t 4 T... 

Nitroprusside. Nitropmsside is a poteat, fast-actiag vasodilator that has to be administered iatravenously by iafusion. It relaxes arterial and venous vascular smooth muscle. Its use is mainly ia hyperteasive crises. Its effects terminate as sooa as iafusioa of the dmg is stopped. 

DHPs are potent arterial vasodilators. They act on resistance vessels and therefore reduce peripheral vascular resistance, lower arterial blood pressure, and antagonize vasospasms in coronary or peripheral arteries. By reducing afterload, DHPs also reduce cardiac oxygen demand. Together with their vascular spasmolytic effect, this explains most of the beneficial actions of DHPs in angina pectoris. Most DHPs are only licensed for the therapy of hypertension, some of them also for the treatment of angina pectoris and vasospastic (Prinzmetal) angina. 

Vasodilators are a group of dtugs, which relax the smooth muscle cells of the blood vessels and lead to an increased local tissue blood flow, a reduced arterial pressure and a reduced central venous pressure. Vasodilators reduce the cardiac pre-load as well as after-load and thereby reduce cardiac work. They are used in a variety of conditions including hypertension, cardiac failure and treatment/prevention of angina pectoris. Major groups are Ca2+-channel blockers (e.g. dihydropyridines), NO-donators (e.g. organic nitrates), K+-channel openers (minoxidil), phosphodiesterase inhibitors (e.g. sildenafil), Rho-kinase inhibitors (e.g. Y27632) or substances with unknown mechanism of action (e.g. hydralazine). Inhibitors of the... 

Adverse reactions associated with these drugs are variable Some of tire more common adverse reactions are listed in tire Summary Drag Table Peripheral Vasodilators and Miscellaneous Vasodilating Drags. Because these drugs dilate peripheral arteries, some degree of hypotension may be associated with their... 

HODGSON J M, PUDDEY I B, BURKE V, WATTS G F and BEILIN L J (2002) Regular ingestion of black tea improves brachial artery vasodilator function , Clin Sci, 102 (2), 195-201. 

In addition to the effects on blood lipids, it has been suggested that soy consumption has a beneficial action on arterial function and improves antioxidant status (Lichtenstein, 1998 and refs therein). Genistein and daidzein were shown to have antioxidant properties in vitro (Kerry and Abbey, 1998), to enhance endothelium-dependent vasodilation and to reduce the development of atherosclerosis in monkeys (Honore et al, 1997 Wagner et al, 1997). 

Increased intrahepatic resistance to portal flow increases pressure on the entire splanchnic bed an enlarged spleen (splenomegaly) is a common finding in cirrhotic patient and can result in thrombocytopenia due to splenic sequestration of the platelets. Portal hypertension mediates systemic and splanchnic arterial vasodilation through production of nitric oxide and other vasodilators in an attempt to counteract the increased pressure gradient. Nitric oxide causes a fall in systemic arterial pressure unfortunately, this activates both the renin-angiotensin-aldosterone and sympathetic nervous systems and... 

As previously discussed, increased portal pressure triggers the release of nitric oxide to directly vasodilate the splanchnic arterial bed and decrease portal pressure. Unfortunately, nitric oxide also dilates the systemic arterial system, causing a decrease in blood pressure and a decrease in renal perfusion by lowering the effective intravascular volume. The kidney reacts by activating the renin-angiotensin-aldosterone system, which increases plasma renin activity, aldosterone production, and sodium retention. This increase in intravascular volume furthers the imbalance of intravascular oncotic pressure, allowing even more fluid to escape to the extravascular spaces. 

Vasodilation and decreased arterial pressure are also detected centrally. The sympathetic nervous system is activated to increase blood pressure, which in turn increases portal pressure. Unchecked, these combined effects enable the cycle of portal pressure and ascites to continue, setting up a self-perpetuating loop of ascites formation. 

Hypertension, or a chronic elevation in blood pressure, is a major risk factor for coronary artery disease congestive heart failure stroke kidney failure and retinopathy. An important cause of hypertension is excessive vascular smooth muscle tone or vasoconstriction. Prazosin, an aradrenergic receptor antagonist, is very effective in management of hypertension. Because oq-receptor stimulation causes vasoconstriction, drugs that block these receptors result in vasodilation and a decrease in blood pressure. 

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