Biomaterial Database

Effect of amiloride on isolated guinea-pig atrium. 1979

A Pousti, and M A Khoyi

The effect of high concentrations (62.5-500 microgram/ml) of amiloride, a potassium sparing diuretic, was investigated in the isolated guinea-pig atrium. Amiloride decreased the frequency of contractions of the spontaneously beating right atrium in a time-dependent fashion. The inotropic effect of amiloride was frequency-dependent. It increased the peak developed tension of the electrically paced left atrium with 1 Hz stimulation. This was dose and time-dependent. Stimulation at 0.35 and 0.1 Hz resulted in no effect and a negative inotropic effect respectively. The effects of amiloride were not prevented by atropine, propranolol, phenoxybenzamine, metiamide, tetrodotoxin or by pretreatment of animals with reserpine. The positive inotropic effect (at 1 Hz) was inhibited by calcium antagonists verapamil or chlorpromazine. The negative inotropic effect (at 0.1 Hz) was prevented by doubling calcium concentration of the medium. Amiloride had no significant effect on sodium, potassium and calcium content of the tissue. It is concluded that high concentrations of amiloride decreases the frequency and changes the peak developed tension of the guinea-pig atrium possibly by decreasing sodium entry and altering the availability of calcium to the contractile elements.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009200	Myocardial Contraction	Contractile activity of the MYOCARDIUM.	Heart Contractility,Inotropism, Cardiac,Cardiac Inotropism,Cardiac Inotropisms,Contractilities, Heart,Contractility, Heart,Contraction, Myocardial,Contractions, Myocardial,Heart Contractilities,Inotropisms, Cardiac,Myocardial Contractions
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D011719	Pyrazines	A heterocyclic aromatic organic compound with the chemical formula C4H4N2.	Pyrazine
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D004347	Drug Interactions	The action of a drug that may affect the activity, metabolism, or toxicity of another drug.	Drug Interaction,Interaction, Drug,Interactions, Drug
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D005260	Female		Females
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D006321	Heart	The hollow, muscular organ that maintains the circulation of the blood.	Hearts