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Chapter-19 Antianginal Drugs

BOOK TITLE: Drug Screening Methods

Author
1. Mohanty Ipseeta
ISBN
9788180613975
DOI
10.5005/jp/books/10243_19
Edition
1/e
Publishing Year
2004
Pages
15
Author Affiliations
1. MGM Medical College, Sector-16, Kamothe, Navi Mumbai 410 705, Maharashtra (India), All India Institute of Medical Sciences, New Delhi, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-110029, India
Chapter keywords
angina pectoris, severe chest pain, coronary blood flow, organic nitrates, atheromatous obstruction, large coronary vessels, positive inotropic effects, negative inotropic effects, coronary vasodilatory effect, calcium antagonism, potassium outflow, glycosides, hypoxic damage, bovine coronary artery, coronary artery ligation, isolated heart-lung preparation, pharmacological processes, cardiac output, electromagnetic blood flowmeter, mean arterial pressure

Abstract

Angina pectoris is severe chest pain that occurs when coronary blood flow is inadequate to supply the oxygen required by the heart. The organic nitrates are mainstay of therapy for immediate relief of angina. The most frequent cause of angina is atheromatous obstruction of the large coronary vessels. In vitro models discuss isolated heart (Langendorff) technique. It is useful to study positive inotropic effects, negative inotropic effects, coronary vasodilatory effect, calcium antagonism, effect on potassium outflow induced by glycosides and determination of hypoxic damage. Calcium antagonism in pitched rat, relaxation of bovine coronary artery, and coronary artery ligation in isolated rat heart are discussed. The isolated heart-lung preparation of the dog is used to study various physiological and pharmacological processes. Cardiac output is recorded with an electromagnetic blood flowmeter and mean arterial pressure from the pneumatic resistance. Coronary drug when administered for prolonged duration leads to increase in the number and size of interarterial collaterals, especially in pigs and dogs. In vivo models explain occlusion of coronary artery. Synthetic catecholamines, such as isoproterenol when injected at high dose produce cardiac necrosis. Stenosis-induced coronary thrombosis model is discussed. This model is characterized by alterations in coronary blood flow with transient platelet aggregation at the site of coronary constriction. Electrical stimulation-induced coronary thrombosis is described. Preliminary preconditioning of the myocardium reduces infarct size, reduces leakage of cellular proteins indicative of myocyte death, and so on. Models of coronary flow measurement are based on measurement of coronary outflow in open and closed chest animal preparations. Electromagnetic flowmeter is discussed. Other models to measure coronary flow are inert gas technique, radioactive technique, radioactive microsphere technique, thermodilution technique, and coronary arteriography. Now-a-days, techniques such as Nuclear Magnetic Resonance (NMR) and Positron Emission Tomography (PET) have increased the ability to study in a noninvasive manner, some aspects of cardiac metabolism, function and coronary flow.

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