Magnesium Potentiates Imipramine Toxicity in the Isolated Rat Heart

Jeffrey Kline, Amy A. DeStefano, JD D. Schroeder, RM M. Raymond

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Study objective: To study the effect of magnesium on cardiac function and hemodynamics during imipramine toxicity. Design: After stabilization, isolated, beating rat hearts were perfused with Krebs-Henseleit bicarbonate buffer (KHB) solution containing 2.0 mg/L imipramine (IMIP) and 2.4 mEq [Mg2+ ] until toxicity, defined as 25% widening of the ventricular depolarization duration (VDD). Experiments were performed at either constant coronary perfusion pressure or flow. Setting: Animal research laboratory of a large, urban hospital. Measurements: Heart rate, VDD, left ventricular pressure and ±dP/dt, and coronary flow. Interventions: On onset of toxicity, KHB+IMIP was switched to either control (KHB+IMIP), magnesium (KHB+IMIP+4.0 or 6.0 mEq/L [Mg2+]), or hypertonic alkaline treatment (165 mEq/L [Na+], pH 7.55). Results: At a constant coronary perfusion pressure of 100 mm Hg, magnesium at 6.0 mEq produced significant decreases in heart rate, left ventricular pressure, +dP/dt, and increase in VDD versus control. With coronary flow held constant, magnesium reduced left ventricular pressure and +dP/dt but not heart rate or VDD. Incidences of electromechanical dissociation and asystole were higher with magnesium versus control. Hypertonic alkaline treatment tended to improve all parameters in constant pressure and constant flow experiments. Conclusion: Magnesium potentiates IMIP-induced negative inotropic effects and cardiac conduction defects in isolated rat hearts. [Kline JA, DeStefano AA, Schroeder JD, Raymond RM: Magnesium potentiates imipramine toxicity in the isolated rat heart. Ann Emerg Med August 1994;24:224-232.].

Original languageEnglish
Pages (from-to)224-232
Number of pages9
JournalAnnals of Emergency Medicine
Volume24
Issue number2
DOIs
StatePublished - 1994
Externally publishedYes

Fingerprint

Imipramine
Magnesium
Bicarbonates
Ventricular Pressure
Heart Rate
Pressure
Perfusion
Urban Hospitals
Heart Arrest
Hemodynamics
Krebs-Henseleit solution
Incidence

ASJC Scopus subject areas

  • Emergency Medicine

Cite this

Magnesium Potentiates Imipramine Toxicity in the Isolated Rat Heart. / Kline, Jeffrey; DeStefano, Amy A.; Schroeder, JD D.; Raymond, RM M.

In: Annals of Emergency Medicine, Vol. 24, No. 2, 1994, p. 224-232.

Research output: Contribution to journalArticle

Kline, Jeffrey ; DeStefano, Amy A. ; Schroeder, JD D. ; Raymond, RM M. / Magnesium Potentiates Imipramine Toxicity in the Isolated Rat Heart. In: Annals of Emergency Medicine. 1994 ; Vol. 24, No. 2. pp. 224-232.
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abstract = "Study objective: To study the effect of magnesium on cardiac function and hemodynamics during imipramine toxicity. Design: After stabilization, isolated, beating rat hearts were perfused with Krebs-Henseleit bicarbonate buffer (KHB) solution containing 2.0 mg/L imipramine (IMIP) and 2.4 mEq [Mg2+ ] until toxicity, defined as 25{\%} widening of the ventricular depolarization duration (VDD). Experiments were performed at either constant coronary perfusion pressure or flow. Setting: Animal research laboratory of a large, urban hospital. Measurements: Heart rate, VDD, left ventricular pressure and ±dP/dt, and coronary flow. Interventions: On onset of toxicity, KHB+IMIP was switched to either control (KHB+IMIP), magnesium (KHB+IMIP+4.0 or 6.0 mEq/L [Mg2+]), or hypertonic alkaline treatment (165 mEq/L [Na+], pH 7.55). Results: At a constant coronary perfusion pressure of 100 mm Hg, magnesium at 6.0 mEq produced significant decreases in heart rate, left ventricular pressure, +dP/dt, and increase in VDD versus control. With coronary flow held constant, magnesium reduced left ventricular pressure and +dP/dt but not heart rate or VDD. Incidences of electromechanical dissociation and asystole were higher with magnesium versus control. Hypertonic alkaline treatment tended to improve all parameters in constant pressure and constant flow experiments. Conclusion: Magnesium potentiates IMIP-induced negative inotropic effects and cardiac conduction defects in isolated rat hearts. [Kline JA, DeStefano AA, Schroeder JD, Raymond RM: Magnesium potentiates imipramine toxicity in the isolated rat heart. Ann Emerg Med August 1994;24:224-232.].",
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AB - Study objective: To study the effect of magnesium on cardiac function and hemodynamics during imipramine toxicity. Design: After stabilization, isolated, beating rat hearts were perfused with Krebs-Henseleit bicarbonate buffer (KHB) solution containing 2.0 mg/L imipramine (IMIP) and 2.4 mEq [Mg2+ ] until toxicity, defined as 25% widening of the ventricular depolarization duration (VDD). Experiments were performed at either constant coronary perfusion pressure or flow. Setting: Animal research laboratory of a large, urban hospital. Measurements: Heart rate, VDD, left ventricular pressure and ±dP/dt, and coronary flow. Interventions: On onset of toxicity, KHB+IMIP was switched to either control (KHB+IMIP), magnesium (KHB+IMIP+4.0 or 6.0 mEq/L [Mg2+]), or hypertonic alkaline treatment (165 mEq/L [Na+], pH 7.55). Results: At a constant coronary perfusion pressure of 100 mm Hg, magnesium at 6.0 mEq produced significant decreases in heart rate, left ventricular pressure, +dP/dt, and increase in VDD versus control. With coronary flow held constant, magnesium reduced left ventricular pressure and +dP/dt but not heart rate or VDD. Incidences of electromechanical dissociation and asystole were higher with magnesium versus control. Hypertonic alkaline treatment tended to improve all parameters in constant pressure and constant flow experiments. Conclusion: Magnesium potentiates IMIP-induced negative inotropic effects and cardiac conduction defects in isolated rat hearts. [Kline JA, DeStefano AA, Schroeder JD, Raymond RM: Magnesium potentiates imipramine toxicity in the isolated rat heart. Ann Emerg Med August 1994;24:224-232.].

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