Saturday, August 6, 2022

Sodium and potassium channel blockade

Q: Blockade of sodium channel leads to prolongation of QT interval on EKG?

A) True
B) False

Answer: B

The rule of thumb is
  • Sodium channel blockade causes prolongation of the QRS interval
  • Potassium channel blockade causes prolongation of the QT interval
Cocaine is a classic example of sodium channel blockade. and antipsychotics are classic examples of potassium channel blockade.



1. Roden DM, George AL Jr. Structure and function of cardiac sodium and potassium channels. Am J Physiol. 1997 Aug;273(2 Pt 2):H511-25. doi: 10.1152/ajpheart.1997.273.2.H511. PMID: 9277464.

2. Balser JR. The cardiac sodium channel: gating function and molecular pharmacology. J Mol Cell Cardiol. 2001 Apr;33(4):599-613. doi: 10.1006/jmcc.2000.1346. PMID: 11273715.

3. Starmer CF, Reddy MR, Namasivayam A, Singh M. Potassium channel blockade amplifies cardiac instability numerical studies of torsades de pointes. Indian J Physiol Pharmacol. 1994 Oct;38(4):259-66. PMID: 7883289.

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