Interaction of diltiazem with propranolol on atrioventricular conduction and refractoriness in the dog

Summary Propranolol pretreatment (0.1 mg·kg^–1) significantly increased the lengthening induced by diltiazem (0.15 mg·kg^–1+0.01 mg·kg^–1·min^–1, 20 min) of the A-H interval of His bundle potential recordings in the dog. In the presence of propranolol, diltiazem also significantly increased the atrioventricular effective refractory period. The results suggest the possible occurrence of AV blocks as a result of the use of a diltiazem-beta blocker combination in clinical practice.Acknowledgments. Financial support from the U.E.R. Biologie Humaine is gratefully acknowledged.     

Isolation from rat brain of a metabolic product,desmethylimipramine, that mediates the antidepressant activity of imipramine (Tofranil)

Zusammenfassung Nach Verabreichung von Imipramin (Tofranil) wurde aus dem Gehirn von Ratten Desmethylimipramin, das N-Monomethylderivat, isoliert. Dieser Metabolit beziehungsweise dessen Anreicherungin vivo scheint für die antidepressive Wirkung von Imipramin verantwortlich zu sein.

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Presented in part as an abstract in Fed. Proc.20, 321 (1961). Some of the material in this communication is taken from a dissertation byJ. V. Dingell to be submitted to the Graduate School of Georgetown University in partial fulfillment of the requirements for the degree of Doctor of Philosophy.