Physiologic Antagonists
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Calcium
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Calcium channel blockers reduce the influx of calcium into myocardial cells, resulting in impaired contractility with clinical manifestations of cardiac failure or hypotension.
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Increasing the extracellular calcium concentration partly overcomes this blockade and reduces these toxic effects.
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Glucagon
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Beta-blockers bind to cardiac beta-receptors and can cause bradycardia, heart block or impaired cardiac contractility. Since they bind with a very high affinity, they are difficult to be displaced with beta agonists.
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Glucagon produces effects on myocardial cells that are similar to those of beta agonists, but it acts by binding to an unrelated class of receptors.
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Glucagon is therefore effective even when there is profound beta blockade.
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Last modified: Wednesday, 28 December 2011, 1:25 AM