BMS 450 Lecture Notes - Calcium Channel, Cgmp-Dependent Protein Kinase, Cardiac Glycoside
Document Summary
Inhibition of the na/ca exchanger decreases calcium efflux. Aka digitalis, is a purified cardiac glycoside extracted from the foxglove plant, digitalis lanata. Digitalis has been used for centuries to treat heart conditions. Activity is regulated solely by the concentration of sodium and calcium. Sodium in the cell will calcium efflux through the exchanger. Stretching the myocardium with increased preload increase the force of contraction. Stretching the myocardium to increase force of contraction has its limits. Too much stretching decreases the force of contraction. Stimulate the chemoreceptor trigger zone in the cns (causes vomiting) Blurred vision, color changes (everything looks yellow; xanthopsia) The desired effects and adverse effects are both concentration-dependent. Digoxin binding is enhanced by low levels of extracellular k+ (hypokalemia) Enhancing the contractile process directly avoids these problems. Increase cardiac contraction by sensitizing the contractile machinery to calcium. Related to an increased affinity of troponin c for calcium.
