The purpose of this study was to evaluate the effect of two local anaesthetics, mepivacaine and lidocaine with epinephrine, on the isolated heart of the frog in vitro, using basic electrophysiological methods.
Materials and Methods: The atria of the heart of 20 frogs were removed and the force and frequency of heart contraction was measured using appropriate data acquisition software. The isolated heart was first bathed in a control saline for 20 min. The control saline was then replaced with saline containing the compound under investigation and after 30 min. incubation the preparation was washed with saline for 20 min. Ten different experiments were conducted for each of the two applied local anaesthetics, mepivacaine and lidocaine with epinephrine 1:80000 having a concentration of 0.81 mM.
Regarding mepivacaine, force and frequency measurements presented a negative inotropic action, while lidocaine with epinephrine revealed a positive one. After the preparation was washed with the control saline, both anaesthetics revealed similar recovery patterns.
In our experiment, the force of heart contraction induced by lidocaine was increased by about 40%, suggesting that lidocaine with epinephrine is more beneficial for the healthy myocardium.
mepivacaine, lidocaine, epinephrine, myocardium, heart contraction, heart rate