Biomaterial Database

Effects of papaverine on Ca++-dependent action potentials in guinea-pig myocardium depolarized by potassium. 1981

M C Sanguinetti, and T C West

Ventricular and atrial tissues isolated from guinea-pig hearts were depolarized by exposure to 22 mM K+ to study the effects of papaverine on the Ca++-mediated slow inward current (Isi). Papaverine at 5 x 10(-6) to 5 x 10(-5) M caused a concentration-dependent decrease in the threshold current required to excite the field-stimulated tissues and an enhancement of action potential amplitude, action potential duration and maximum rate of depolarization of the Ca++-dependent action potentials. In ventricular preparations, 5 x 10(-5) and 10(-4) M papaverine invariably induced rhythmic spontaneous activity that was abolished by verapamil. It is proposed that the membranal electrical effects of papaverine in the K+-depolarized myocardium are caused by an enhancement of Isi and a decrease in K+ conductance. However, at the highest concentration studied (10(-4) M), papaverine inhibited Isi in atrial tissue, demonstrating that papaverine exerts another action on Isi opposite to that observed at lower concentrations.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D010208	Papaverine	An alkaloid found in opium but not closely related to the other opium alkaloids in its structure or pharmacological actions. It is a direct-acting smooth muscle relaxant used in the treatment of impotence and as a vasodilator, especially for cerebral vasodilation. The mechanism of its pharmacological actions is not clear, but it apparently can inhibit phosphodiesterases and it may have direct actions on calcium channels.	Cerespan,Papaverine Hydrochloride,Pavabid,Pavatym,Hydrochloride, Papaverine
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.
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
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
D006325	Heart Atria	The chambers of the heart, to which the BLOOD returns from the circulation.	Heart Atrium,Left Atrium,Right Atrium,Atria, Heart,Atrium, Heart,Atrium, Left,Atrium, Right
D006352	Heart Ventricles	The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.	Cardiac Ventricle,Cardiac Ventricles,Heart Ventricle,Left Ventricle,Right Ventricle,Left Ventricles,Right Ventricles,Ventricle, Cardiac,Ventricle, Heart,Ventricle, Left,Ventricle, Right,Ventricles, Cardiac,Ventricles, Heart,Ventricles, Left,Ventricles, Right
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential