Biomaterial Database

Comparison of the electrophysiological effects of two neuroleptics, melperone and thioridazine, on isolated rat atria. 1978

H Refsum, and M Passwal, and S O Olsson

The effects of the two neuroleptics, melperone (a butyrophenone) and thioridazine (a phenothiazine), were compared on the electrical and mechanical activity of isolated rat atria. Both electrically stimulated and spontaneously beating atria were used. Melperone was found to prolong the effective refractory period while the threshold for electrical stimulation i.e. the excitability, was almost unaffected. Thioridazine caused a similar prolongation of the effective refractory period, but also decreased the excitability significantly. In contrast to melperone, thioridazine had a negative inotropic effect. The spontaneous pacemaker activity was depressed and the sinus node recovery time increased to a greater extent after melperone than after thioridazine. The results taken together with other recent data support the hypothesis that melperone may be a type III anti-arrhythmic according to the classification of Vaughan Williams, in contrast to thioridazine which has a quinidine-like action (type I). The results also indicate that melperone in addition to prolonging the effective refractory period, may act as an anti-arrhythmic agent by depressing automaticity.

UI	MeSH Term	Description	Entries
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
D010880	Piperidines	A family of hexahydropyridines.
D012032	Refractory Period, Electrophysiological	The period of time following the triggering of an ACTION POTENTIAL when the CELL MEMBRANE has changed to an unexcitable state and is gradually restored to the resting (excitable) state. During the absolute refractory period no other stimulus can trigger a response. This is followed by the relative refractory period during which the cell gradually becomes more excitable and the stronger impulse that is required to illicit a response gradually lessens to that required during the resting state.	Period, Neurologic Refractory,Periods, Neurologic Refractory,Refractory Period, Neurologic,Tetanic Fade,Vvedenskii Inhibition,Wedensky Inhibition,Inhibition, Vvedenskii,Inhibition, Wedensky,Neurologic Refractory Period,Neurologic Refractory Periods,Neuromuscular Fade,Neuromuscular Transmission Fade,Refractory Period, Neurological,Refractory Periods, Neurologic,Electrophysiological Refractory Period,Electrophysiological Refractory Periods,Fade, Neuromuscular,Fade, Neuromuscular Transmission,Fade, Tetanic,Neurological Refractory Period,Neurological Refractory Periods,Refractory Periods, Electrophysiological,Refractory Periods, Neurological,Transmission Fade, Neuromuscular
D002090	Butyrophenones	Compounds containing phenyl-1-butanone.
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
D006321	Heart	The hollow, muscular organ that maintains the circulation of the blood.	Hearts
D006339	Heart Rate	The number of times the HEART VENTRICLES contract per unit of time, usually per minute.	Cardiac Rate,Chronotropism, Cardiac,Heart Rate Control,Heartbeat,Pulse Rate,Cardiac Chronotropy,Cardiac Chronotropism,Cardiac Rates,Chronotropy, Cardiac,Control, Heart Rate,Heart Rates,Heartbeats,Pulse Rates,Rate Control, Heart,Rate, Cardiac,Rate, Heart,Rate, Pulse
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012849	Sinoatrial Node	The small mass of modified cardiac muscle fibers located at the junction of the superior vena cava (VENA CAVA, SUPERIOR) and right atrium. Contraction impulses probably start in this node, spread over the atrium (HEART ATRIUM) and are then transmitted by the atrioventricular bundle (BUNDLE OF HIS) to the ventricle (HEART VENTRICLE).	Sinuatrial Node,Sinus Node,Sino-Atrial Node,Sinu-Atrial Node,Node, Sino-Atrial,Node, Sinoatrial,Node, Sinu-Atrial,Node, Sinuatrial,Node, Sinus,Nodes, Sino-Atrial,Nodes, Sinoatrial,Nodes, Sinu-Atrial,Nodes, Sinuatrial,Nodes, Sinus,Sino Atrial Node,Sino-Atrial Nodes,Sinoatrial Nodes,Sinu Atrial Node,Sinu-Atrial Nodes,Sinuatrial Nodes,Sinus Nodes