The Possible Mode of Action of Antiarrhythmic Agents

Hoffman, Brian F.; Briller, Stanley A.; Conn, Hadley L.

doi:10.9783/9781512814798-011

Cited by 17 publications

(20 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the latter fibers the curve relating upstroke velocity to the level of membrane potential was displaced to the right and down. Similar effects are produced by other antiarrhythmic agents (24,25) and are considered important with regard to their action. Such changes may prolong the effective refractory period even without prolonging the action potential (25).…”

Section: Discussionmentioning

confidence: 79%

“…Similar effects are produced by other antiarrhythmic agents (24,25) and are considered important with regard to their action. Such changes may prolong the effective refractory period even without prolonging the action potential (25). If, as in the present study, duration of the action potential decreases simultaneously with the reduction in velocity of the upstroke, changes in refractoriness cannot be predicted and must be measured.…”

Section: Discussionmentioning

confidence: 79%

“…Treatment with the two higher concentrations of drug shifted the curves to the right and down, an indication of a decrease in the ability of the fiber to depolarize at given levels of membrane potential. This effect on the ability to depolarize is caused by several other agents with antiarrhythmic properties (24,25).…”

Section: Effect Of Propranolol On the Contour Of The Transmembrane Acmentioning

confidence: 99%

See 2 more Smart Citations

Effects of Propranolol on the Transmembrane Potentials of Ventricular Muscle and Purkinje Fibers of the Dog

Davis

Temte

1968

Circulation Research

195

View full text Add to dashboard Cite

Papillary muscle-false tendon tissue preparations isolated from dog hearts were perfused with Tyrode's solution containing propranolol in concentrations ranging from 0.1 to 20.0 mg/liter. Transmembrane action potentials of both ventricular muscle fibers and Purkinje fibers were recorded. With sufficient concentration of drug, the velocity of the upstroke and the overshoot of both fiber types decreased. The curve relating upstroke velocity to level of membrane potential for Purkinje fibers was displaced to the right and down. The ability of both ventricular muscle fibers and Purkinje fibers to respond to rapid frequencies of stimulation was decreased. Repolarization of Purkinje fibers was accelerated by propranolol, but repolarization of ventricular muscle fibers was unaffected. Duration of the effective refractory period of Purkinje fibers decreased; that of ventricular muscle fibers was unchanged. Graded responses and decremental impulse conduction in Purkinje fibers were abolished in the presence of propranolol. Low doses of propranolol which caused no change in the transmembrane potential completely blocked the increase in Purkinje diastolic depolarization normally induced by epinephrine. The possible mechanisms by which propranolol might exert its antiarrhythmic actions on ventricular arrhythmias were discussed. ADDITIONAL KEY WORDS cardiac arrhythmias effective refractory period epinephrine diastolic depolarization rapid electrical stimulation• A number of currently available drugs can block catecholamine beta-receptors (1-5). Many of these compounds exert actions against certain experimentally-induced cardiac arrhythmias. Dichloroisoproterenol, pronethalol, and propranolol prevent the ventricular arrhythmias induced by catecholamines (6-11) and prevent or terminate the ventricular arrhythmias induced by cardiac glycosides (8-16). Other drugs that are unrelated chemically to the above group but also block beta-receptors (4, 5) prevent the arrhythmias induced by catecholamines but not those elicited by cardiac glycosides (8, 9,

show abstract

Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 79%

Section: Effect Of Propranolol On the Contour Of The Transmembrane Acmentioning

confidence: 99%

See 1 more Smart Citation

Effects of Propranolol on the Transmembrane Potentials of Ventricular Muscle and Purkinje Fibers of the Dog

Davis

Temte

1968

Circulation Research

195

View full text Add to dashboard Cite

show abstract

“…Interpretation of the possible role of these changes can be made within a framework provided by a number of recent reviews in which the specific electrophysiological changes thought to operate in genesis of cardiac arrhythmias were classified and discussed (30)(31)(32)(33). In addition, we believe it instructive to compare the effects of lidocaine with those of other antiarrhythmic agents which differ chemically from each other but which antagonize the same types of ventricular arrhythmias.…”

Section: Davis Temtementioning

confidence: 99%

“…The importance of decremental conduction (38) in production of conduction disturbances and reentry of excitation has been emphasized repeatedly (30)(31)(32)(33). Such conduction can occur when, for any reason, a fiber is excited at a reduced level of membrane potential.…”

Section: Davis Temtementioning

confidence: 99%

Electrophysiological Actions of Lidocaine on Canine Ventricular Muscle and Purkinje Fibers

Davis

Temte

1969

Circulation Research

157

View full text Add to dashboard Cite

Isolated canine papillary muscles with attached false tendons were perfused with Tyrode's solution containing lidocaine. Transmembrane action potentials of ventricular muscle fibers and Purkinje fibers were recorded with glass microelectrodes. Repolarization of Purkinje fibers was accelerated by lidocaine but that of ventricular muscle fibers was unaffected. The maximum rate of rise of the action potential of Purkinje fibers decreased only at 50.0 mg/ liter lidocaine; that of ventricular muscle fibers was unchanged by any concentration. The curve relating rate of rise of premature responses to level of membrane potential for Purkinje fibers was unchanged with 5.0 mg/liter but shifted down and to the right with 10.0 and 50.0 mg/liter. The effective refractory period of Purkinje fibers shortened at 5.0 and lengthened at 50.0 mg/liter. The level of membrane potential needed to elicit premature propagated responses in Purkinje fibers with a standardized test stimulus increased and the earliest responses obtained in the presence of lidocaine were relatively large. Duration of the effective refractory period of ventricular muscle fibers was unchanged with 5.0 mg/liter but lengthened progressively with 10.0 and 50.0 mg/liter. Lidocaine impaired the ability of both fibers to respond to rapid frequencies of stimulation, slowed the rate of inherent diastolic depolarization of driven Purkinje fibers, decreased the rate of discharge of spontaneously beating preparations, and minimized the increase in rate and magnitude of diastolic depolarization caused normally by epinephrine. The possible role of these effects of lidocaine in regard to its antiarrhythmic actions was discussed.

show abstract

Action of some cardiovascular and neurohumoral agents on the formation of the chick embryo heart. I. Morphology

Butros

1972

Teratology

View full text Add to dashboard Cite

A study of some cardiovascular drugs was made with early chick blastoderms (stages 5–6) cultured in vitro to determine their action on the initiation of heart primordia. Ouabain (16–22 μ/ml) completely prevented the appearance of heart primordia and caused slight cytolysis of the brain and somites. Quinidine (15 μg/ml) caused swelling of the formed hearts but they were noncontracting. Atropine (100 μg/ml) had a slight cytolytic effect on the heart and more so on the brain. Epinephrine (25 μg/ml) had a strong cytolytic action but no selective action on any system. Acetylcholine (up to 500 μg/ml) had no inhibitory effect on development.

show abstract

The Possible Mode of Action of Antiarrhythmic Agents

Cited by 17 publications

References 0 publications

Effects of Propranolol on the Transmembrane Potentials of Ventricular Muscle and Purkinje Fibers of the Dog

Effects of Propranolol on the Transmembrane Potentials of Ventricular Muscle and Purkinje Fibers of the Dog

Electrophysiological Actions of Lidocaine on Canine Ventricular Muscle and Purkinje Fibers

Action of some cardiovascular and neurohumoral agents on the formation of the chick embryo heart. I. Morphology

Contact Info

Product

Resources

About