The cellular electropharmacology of mexiletine in papillary muscles of guinea pigs chronically treated with amiodarone.

The cellular electropharmacology of mexiletine in papillary muscles of guinea pigs chronically treated with amiodarone. Research Abstract Details 

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The cellular electropharmacology of mexiletine in papillary muscles of guinea pigs chronically treated with amiodarone. Abstract Text:

N D Berman,L Y Wang,R I Ogilvie,

OBJECTIVE: The combination of mexiletine and amiodarone has proved useful in the control of serious ventricular arrhythmias, but the electrophysiological basis for their effectiveness in combination is unknown. The objective of this study was to compare the effects of mexiletine on action potential parameters of papillary muscles taken from guinea pigs chronically treated with amiodarone, with tissue taken from a control group. DESIGN: The effects of 12.5 to 200 microM mexiletine on action potential parameters of papillary muscles taken from guinea pigs chronically treated with amiodarone were compared with tissue taken from a control group, at frequencies of 1.0, 1.5 and 3.0 Hz, using standard microelectrode techniques. Onset of use-dependent block was assessed by 30 beat trains, and recovery from block by extrastimuli at diastolic intervals ranging from 200 to 5000 ms at both 1.5 and 3.0 Hz. ANIMALS: Eighteen four-week-old guinea pigs were randomly divided into two groups. One group received amiodarone in a loading dose of 20 mg/kg/day by intraperitoneal injection for one week, followed by 10 mg/kg/day for 15 weeks. The control animals were given equivalent volumes of dextrose intraperitoneally for 16 weeks. MAIN RESULTS: Mexiletine depressed the maximum rate of depolarization of phase 0 of the action potential (Vmax) in a concentration- and use-dependent fashion. Whereas chronic amiodarone treatment did not alter steady-state Vmax values, the extent of tonic Vmax depression induced by mexiletine was decreased, while use-dependent depression was increased. Mexiletine combined with amiodarone increased effective refractory period prolongation from 306.7 +/- 27.2 to 348.8 +/- 37.2 ms, while action potential duration shortening of mexiletine was moderated from 134.0 +/- 19.8 to 151.0 +/- 8.3 ms (to 90% repolarization at 3 Hz in the presence of 200 microM mexiletine).

The cellular electropharmacology of mexiletine in papillary muscles of guinea pigs chronically treated with amiodarone. Publishing Authors By Initials

ND Berman,LY Wang,RI Ogilvie,

For similar musculoskeletal, neural, and ocular physiology: nervous system physiology: nervous system physiologic phenomena: refractory period, electrophysiological research abstracts see: musculoskeletal, neural, and ocular physiology: nervous system physiology: nervous system physiologic phenomena: refractory period, electrophysiological research

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The cellular electropharmacology of mexiletine in papillary muscles of guinea pigs chronically treated with amiodarone. Journal Published:

PUBLICATION TYPE: Research Support, Non-U.S. Gov

Journal: The Canadian journal of cardiology

VOLUME: 8

Page Numbers: 69-77

Journal Abbreviation:

ISSN: 1916-7075

DAY: 3

MONTH: 04

YEAR: 2008

The cellular electropharmacology of mexiletine in papillary muscles of guinea pigs chronically treated with amiodarone. Information

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LANGUAGE: eng

NlmUniqueID: 8510280

The cellular electropharmacology of mexiletine in papillary muscles of guinea pigs chronically treated with amiodarone. Keywords Mesh Terms:

KEYWORDS: Refractory Period, Electrophysiological

MESH TERMS: drug effects

Chemical & Substance for Abstract: The cellular electropharmacology of mexiletine in papillary muscles of guinea pigs chronically treated with amiodarone. Information

Substance Name: Mexiletine

Registry Number: 31828-71-4

Grant and Affiliation Information for The cellular electropharmacology of mexiletine in papillary muscles of guinea pigs chronically treated with amiodarone.

AFFILIATION: Division of Cardiology, Toronto Western Hospital, Ontario.

Country: CANADA

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MEDLINETA: Can J Cardiol

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