Propranolol inhibits IK(Ado) by competitive A1-receptor interaction

Zeitschrift für Kardiologie
B BrandtsH-J Trappe

Abstract

Betablocking agents are known to exert anti-arrhythmic effects in ischemic myocardium due to blockade of myocardial beta-1-receptors. Since adenosine (Ado) induced muscarinic potassium current (IK(Ado)) and ATP sensitive potassium current (IK(ATP)) are discussed to be activated during ischemia we studied the effect of propranolol on IK(Ado) and IK(ATP). The effect of propranolol on muscarinic potassium current and IK(ATP) was studied in isolated rat atrial myocytes by means of the whole-cell voltage clamp tech- nique. Propranolol (50 microM) completely inhibited IK(Ado). IC50 was 7 microM. Inhibition of acetylcholine induced current (IK(ACh)) and GTP-gamma-S induced muscarinic potassium current was less potent (IC50 29 microM and 31 microM respectively). Propranolol was active from the outside only. Intracellular application did not significantly affect muscarinic potassium current. (+)-propranolol, an isomer without beta-blocking properties, was as effective as (+/-)-propranolol. The inwardly rectifying potassium current IK(ATP) showed minor sensitivity to the compound (10% current reduction, propranolol 50 microM). Propranolol inhibits IK(Ado). Inhibition is not due to beta-receptor blockade. Predominantly an interaction with...Continue Reading

Citations

Jan 29, 2013·Daru : Journal of Faculty of Pharmacy, Tehran University of Medical Sciences·Babak FallahiMohammad Eftekhari
Aug 3, 2005·Journal of Experimental Psychology. Learning, Memory, and Cognition·Michael R HealyChristie Chung

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