In vivo and in vitro bradycardia induced by local anesthetics is potentiated by calcium channel blockers.
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Date
2009-04
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Abstract
The present study examined the interactions of local anesthetics
(LA) and calcium channel blockers (CCBs) on rhythmicity of heart using
in vivo and in vitro experiments. ECG recordings were made from the
anesthetized rats for in vivo preparations and spontaneously beating isolated
rat right atrial potential for the in vitro experiments. The in vivo
experiments with LA showed dose-dependent bradycardia with lignocaine
(LIG, 100-500 μg/kg) and bupivacaine (BUP, 10-100 μg/kg). BUP was 4-5
times more potent than LIG. Verapamil (VML) and diltiazem (DTZ), CCBs
also produced dose (10-100 μg/kg) -dependent bradycardia. However, none
of them affected the PR/QT interval or QRS complex. Further, LA-induced
bradycardia was potentiated by CCBs. In addition, flattening of P-wave in
ECG was observed with doses (10-25 μg/kg) of LA in the presence of CCBs.
Similarly, the in vitro experiments demonstrated a concentration-dependent
decrease in atrial rate by BUP or VML. The BUP-induced decrease was
potentiated in the presence of VML. Thus, the results suggest that CCBs
potentiate the LA-induced bradycardia by involving pacemaker activity.
Further, the flattening of P-wave in ECG serves as an early indicator of
the cardiotoxicity produced by these drugs.
Description
Keywords
local anesthetic, calcium channel blockers, bradycardia, bupivacaine, lignocaine, verapamil, diltiazem
Citation
Mandal Maloy B, Sahu Manoj K, Mandal Sanchayan, Gupta P K. In vivo and in vitro bradycardia induced by local anesthetics is potentiated by calcium channel blockers. Indian Journal of Physiology and Pharmacology. 2009 Apr-June; 53(2): 155-162.