Cardiac glycoside
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223054797
2008-07-02T10:56:29Z
BOTarate
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robot Adding: [[es:Glucósido cardiaco]]
'''Cardiac glycosides''' are [[medication|drugs]] used in the treatment of [[congestive heart failure]] and cardiac [[arrhythmia]]. These [[glycoside]]s are found as [[secondary metabolite]]s in several [[plant]]s, but also in some animals. Some of these compounds ([[ouabain]] and some frog poisons) are used in Africa as arrow-poisons for hunting.
==Function==
Cardiac glycosides work by inhibiting the [[NaKATPase|Na<sup>+</sup>/K<sup>+</sup> pump]]. This causes an increase in the level of [[sodium]] [[ion]]s in the myocytes, which then leads to a rise in the level of [[calcium]] ions. This inhibition increases the amount of [[Calcium|Ca]]<sup>2+</sup> [[ion]]s available for contraction of the heart [[muscle]], improves cardiac output and reduces distention of the heart.
They do this by stabilizing the E2-P transition state of the [[NaKATPase|Na<sup>+</sup>/K<sup>+</sup> pump]]. The proposed mechanism is the following: inhibition of the Na<sup>+</sup>/K<sup>+</sup> pump leads to increased Na<sup>+</sup> levels, which in turn slows down the extrusion of Ca<sup>2+</sup> via the [[Sodium-calcium exchanger|Na<sup>+</sup>/Ca<sup>2+</sup> exchange pump]]. Increased amounts of Ca<sup>2+</sup> are then stored in the [[sarcoplasmic reticulum]] and released by each [[action potential]].
They have an [[antiarrhythmic]] effect by prolonging the refractory period of the AV node ([[Atrioventricular node]]), reducing the number of impulses reaching the [[Ventricle (heart)|ventricle]]s. Cardiac output is restored but [[atrial fibrillation]] or atrial flutter are not abolished.
==Examples==
Examples of plants producing cardiac glycosides:
* ''[[Strophanthus]]'' - [[ouabain]] g/k/e-strophanthin
* ''[[Digitalis]] lanata'' and ''Digitalis purpurea'' - [[digoxin]], [[digitoxin]]
* ''[[Urginea maritima|Scilla maritima]]'' - proscillaridine A
* ''Adonis vernalis, Adonis aestivalis''
* ''Acokanthera oblongifolia''
* ''[[Convallaria]]'' (lily of the valley)
Some frog-poison contain [[bufalin]], [[marinobufagenin]] and [[bufadienolide]]s, cardiac glycosides.
==See also==
*[[Cardenolide aglycones]]
==External links==
{{Glycosides}}
{{Cardiac glycosides}}
[[Category:Cardiac glycosides| ]]
[[Category:Glycosides]]
[[cs:Srdeční glykosidy]]
[[de:Herzglykoside]]
[[et:Südameglükosiidid]]
[[es:Glucósido cardiaco]]
[[fr:Glycoside cardiotonique]]
[[ja:強心配糖体]]
[[pl:Glikozydy nasercowe]]
[[pt:Cardioglicosideo]]
[[vi:Glicozit tim]]
[[zh:强心甙类]]