PMID: 6849253Jan 1, 1983Paper

Biphasic nature of propranolol's microelectrophysiologic effects

The American Journal of Cardiology
D H IansmithJ P Bandura


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


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


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
Atrial Function

Related Feeds

Cardiovascular Diseases: Risk Factors

Cardiovascular disease is a significant health concern. Risk factors include hypertension, obesity, dyslipidemia and smoking. Women who are postmenopausal are at an increased risk of heart disease. Here is the latest research for risk factors of cardiovascular disease.