Template:Digoxin mechanism: Difference between revisions

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Digoxin’s inhibits of the Na+/K+ ATPase, in the myocardium causing an increase in intracellular sodium levels, resulting in a reversal of the action of the sodium-calcium exchanger. The exchanger normally imports three extracellular sodium ions into the cardiac myocyte in exchange for one intracellular calcium being exported. By inhibiting the ATPase sodium accumulates intracellularly and is exchanged for Calcium.  The reversal of this exchange causes an increase in the intracellular calcium concentration increasing contractility. There is also a lengthening of phase 4 and phase 0 of the cardiac action potential which ultimately decreases heart rate.<ref>Gheorghiade M. et al. Digoxin in the Management of Cardiovascular Disorders. Circulation. 2004; 109: 2959-2964</ref>
*Inhibits Na+/K+ ATPase in the myocardium<ref>Gheorghiade M. et al. Digoxin in the Management of Cardiovascular Disorders. Circulation. 2004; 109: 2959-2964</ref>
**Causes increase in intracellular sodium levels
**Results in reversal of sodium-calcium exchanger (normally imports three extracellular sodium ions into the cardiac myocyte in exchange for one intracellular calcium being exported)
**Sodium accumulates intracellularly and is exchanged for Calcium.   
**Causes an increase in the intracellular calcium concentration increasing contractility
***Also a lengthening of phase 4 and phase 0 of the cardiac action potential which ultimately decreases heart rate
*Summary
**Inhibits NaK pump
***Positive inotropy
**Negative chronotropy/dromotropy
***Indirect vagal stimulator

Revision as of 22:29, 12 September 2015

  • Inhibits Na+/K+ ATPase in the myocardium[1]
    • Causes increase in intracellular sodium levels
    • Results in reversal of sodium-calcium exchanger (normally imports three extracellular sodium ions into the cardiac myocyte in exchange for one intracellular calcium being exported)
    • Sodium accumulates intracellularly and is exchanged for Calcium.
    • Causes an increase in the intracellular calcium concentration increasing contractility
      • Also a lengthening of phase 4 and phase 0 of the cardiac action potential which ultimately decreases heart rate
  • Summary
    • Inhibits NaK pump
      • Positive inotropy
    • Negative chronotropy/dromotropy
      • Indirect vagal stimulator
  1. ↑ Gheorghiade M. et al. Digoxin in the Management of Cardiovascular Disorders. Circulation. 2004; 109: 2959-2964
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