Abstract
Clinical studies have shown age related differences in the cardiac electrophysiologic responses to some cardioactive drugs. We used standard microelectrode techniques to determine whether there are age related changes in the effects of lidocaine (L) and quinidine (Q) on cardiac cellular electrophysiologic properties. Neonatal (N) and adult (A) canine cardiac Purkinje fibers were superfused with L 2-40mg/1 or Q 0.5-20mg/1. The threshold concentration for L effects on action potential (AP) amplitude was 40 mg/1 for N and 20mg/1 for A; on maximum upstroke velocity of phase 0 depolarization (Vmax) 5mg/1 for N and 2mg/1 for A; on action potential duration (APD) 2mg/1 for both N and A. The threshold concentration for Q effects on AP amplitude was 2.5mg/1 for both N and A; on V max 1.25/1 for both N and A; on APD 1.25mg/1 for both N and A. For all variables studied the maximum effects of L on A action potential characteristics were greater than on N. For Q, the maximum effects were greater on N than on A. These studies indicate that there are significant age related differences in the cellular electrophysiologic responses to L and Q which vary depending on the drug studied. The ionic mechanisms underlying these observations remain to be determined.
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Hordof, A., Mary-Rabine, L., Rosen, M. et al. 120 EFFECTS OF LIDOCAINE AND QUINIDINE ON THE ELECTROPHYSIOLOGIC PROPERTIES OF NEONATAL AND ADULT CANINE CARDIAC PURKINJE FIBERS. Pediatr Res 12 (Suppl 4), 383 (1978). https://doi.org/10.1203/00006450-197804001-00125
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DOI: https://doi.org/10.1203/00006450-197804001-00125