PMID: 6849253Jan 1, 1983Paper

Biphasic nature of propranolol's microelectrophysiologic effects

The American Journal of Cardiology
D H IansmithJ P Bandura

Abstract

The microelectrophysiologic effects of d,l-propranolol were observed to be biphasic when a wide range of concentrations was used in canine atrial tissue; therefore, the 2 isomers were used separately to test the hypothesis that the opposite effects of propranolol could be separated by isomeric isolation. Whole atria were detached from dog hearts and 3 by 0.5 cm strips were cut from the atria. Transmembrane action potentials were monitored from the atrial strips mounted in an isolation chamber containing Tyrode's solution. Concentrations of d-propranolol, l-propranolol, and the d,l-racemate ranging from 0.03 to 1.0 micrograms/ml were added to the bath and the effects observed for 60 minutes. In lower concentrations d,l-propranolol decreased the effective refractory period and activation time while increasing maximal rise velocity, action potential amplitude, and resting membrane potential. Higher concentrations produced the opposite effects. The l-isomer produced effects very similar to those of the lower concentrations of the racemate, whereas the d-form mimicked those effects of the higher concentrations of the racemic mixture. We conclude that d,l-propranolol is capable of exerting 2 opposite electropharmacologic actions, whi...Continue Reading

References

Sep 1, 1978·Journal of Pharmaceutical Sciences·B W Hadzija, A M Mattocks
Sep 1, 1978·Clinica Chimica Acta; International Journal of Clinical Chemistry·P S RaoH S Mueller
Mar 1, 1969·Progress in Cardiovascular Diseases·B R Lucchesi, L S Whitsitt
Feb 1, 1965·The Journal of Pharmacology and Experimental Therapeutics·P SOMANI, B K LUM

Citations

Mar 1, 1992·American Heart Journal·W R Davis, S F Schaal
Sep 1, 1986·British Journal of Pharmacology·M BoucherJ L Moundanga

Related Concepts

Nerve Impulses
Cardiac Depressants
Canis familiaris
Dose-Response Relationship, Drug
Electrophysiology (Science)
Right Atrial Structure
Isomerism
Rexigen
Atrial Function

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