Cardiac glycosides are drugs used in the treatment of
congestive heart failureand cardiac arrhythmia. These glycosides are found as secondary metabolites in several plants, but also in some animals. Some of these compounds ( ouabainand some frog poisons) are used in Africa as arrow-poisons for hunting.
Cardiac glycosides work by inhibiting the Na+/K+ pump. This causes an increase in the level of
sodium ions in the myocytes, which then leads to a rise in the level of calciumions. This inhibition increases the amount of Ca2+ ions 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 Na+/K+ pump. The proposed mechanism is the following: inhibition of the Na+/K+ pump leads to increased Na+ levels, which in turn slows down the extrusion of Ca2+ via the Na+/Ca2+ exchange pump. Increased amounts of Ca2+ are then stored in the
sarcoplasmic reticulumand released by each action potential.
They have an
antiarrhythmiceffect by prolonging the refractory period of the AV node ( Atrioventricular node), reducing the number of impulses reaching the ventricles. Cardiac output is restored but atrial fibrillationor atrial flutter are not abolished.
Examples of plants producing cardiac glycosides:
Strophanthus" – ouabaing/k/e-strophanthin
Digitalislanata" and "Digitalis purpurea" – digoxin, digitoxin
* "Scilla maritima" – proscillaridine A
* "Adonis vernalis, Adonis aestivalis"
* "Acokanthera oblongifolia"
Convallaria" (lily of the valley)
Some frog-poisons contain
bufalin, marinobufageninand bufadienolides, cardiac glycosides.
Wikimedia Foundation. 2010.
Look at other dictionaries:
cardiac glycoside — noun obtained from a number of plants and used to stimulate the heart in cases of heart failure • Syn: ↑cardiac glucoside • Hypernyms: ↑steroid • Hyponyms: ↑digitalis, ↑digitalis glycoside, ↑digitalin * * * … Useful english dictionary
cardiac glycoside — any of a group of glycosides characterized by an aglycone consisting of a steroid nucleus with an α,β unsaturated lactone ring attached at the C 17 position, occurring in certain plants (e.g., Digitalis, Strophanthus, Urginea). Cardiac… … Medical dictionary
cardiac glycoside — Pharm. any of a group of drugs used to stimulate the heart in cases of heart failure, obtained from a number of plants, as the foxglove, squill, or yellow oleander. Also, cardiac glucoside. * * * … Universalium
cardiac glycoside — /kadiæk ˈglaɪkəsaɪd/ (say kahdeeak gluykuhsuyd) noun one of a group of sugar containing drugs used to stimulate the heart in cases of heart failure, obtained from a number of plants, as the foxglove, squill, or yellow oleander. Also, cardiac… … Australian English dictionary
cardiac glycoside — Specific blockers of the > especially of heart muscle, eg. strophanthin … Dictionary of molecular biology
Glycoside — Genin redirects here. For the ninja rank, see Ninja#Development. Salicin, a glycoside related to aspirin … Wikipedia
cardiac glucoside — noun obtained from a number of plants and used to stimulate the heart in cases of heart failure • Syn: ↑cardiac glycoside • Hypernyms: ↑steroid • Hyponyms: ↑digitalis, ↑digitalis glycoside, ↑digitalin … Useful english dictionary
glycoside — glycosidic /gluy keuh sid ik/, adj. /gluy keuh suyd /, n. Biochem. any of the class of compounds that yield a sugar and an aglycon upon hydrolysis. [1925 30; GLYCOSE + IDE] * * * Any of a wide variety of naturally occurring organic compounds in… … Universalium
glycoside — Condensation product of a sugar with any other radical involving the loss of the OH of the hemiacetal or hemiketal of the sugar, leaving the anomeric carbon as the link; thus, the condensation through the carb … Medical dictionary
cardiac glycosides — see glycoside, digoxin … The new mediacal dictionary