Effects of platelet activating factor on action potentials and potassium channels in guinea-pig ventricular myocytes

( views:56, downloads:0 )
Journal Title:
Volume 56, Issue 03, 2004
Key Word:
platelet activating factor;cardiac myocyte;action potential;potassium channels;patch clamp technique

Abstract: This study was designed to investigate the effects of platelet activating factor (PAF) on the action potential and potassium currents in guinea-pig ventricular myocytes. Whole cell patch clamp techniques were used. With 5 mmol/L ATP in the pipette electrode (mimic normal condition), 1 μmol/L PAF increased APD90 from 225.8±23.3 to 352.8±29.8 ms (n=5, P<0.05), decreased IK1 and IK tail currents from -6.1±1.3 to -5.6±1.1 nA (n=5, P<0.05) at -120 mV and from 173.5±16.7 to 152.1±11.5 pA (P<0.05, n=4) at +30 mV,respectively. But PAF had no effect on IK1 at potentials within the normal range of membrane potentials (between -90 mV and +20 mV).restore prolongation of APD induced by PAF. In conclusion, in guinea-pig ventricular myocytes, with 5 mmol/L ATP in the pipette PAF hence a decrease in APD. It is suggested that PAF may amplify the heterogeneity between ischemic and normal cardiac myocytes during ischemia/reperfusion, which may play a vital role in the pathogenesis of the arrhythmias induced by ischemia/reperfusion.

  • [1]Montrucchio G, Alloatti G, Camussi G. Role of platelet-activating factor in cardiovascular pathophysiology. Physiol Rev 2000; 80(4):1669-1699.
  • [2]Flores NA, Sherian DJ. Electrophysiological and arrhythmogenic effects of platelet activating factor during normal perfusion, myocardial ischemia and reperfusion in the guinea-pig. Br J PharmocalDU Yi-Mei et al: Effects of PAF on AP and K+ Current 1990;101:734-738.
  • [3]Hoffman BF, Guo SD, Feinmark SJ. Arrhythmias caused by platelet activating factor. J Cardiovasc Electrophysiol 1996; 7(2): 120-133.
  • [4]Tristani-Firouzi M, Chen J, Mitcheson JS, Sanguinetti MC.Molecular biology of K+ channels and their role in cardiac arrhythmias. Am J Med 2001; 110(1):50-59.
  • [5]Billman GE. Role of ATP-sensitive potassium channel in extracellar potassium accumulation and cardiac arrhythmias during myocardial ischaemia. Cardiovasc Res 1994; 28(6):762-769.
  • [6]Carmeliet E. Cardiac ionic and acute ischemia:from channels to arrhythmias. Physiological Rev 1999;79(3): 917-1017.
  • [7]Du YM, Tang M, Liu C J, Luo HY, Hu XW. Inhibitory effect of adrenomedullin on L-type calcium currents in guinea-pig ventricular myocytes. Acta Physiol Sin 2002; 54 (6):479-484.
  • [8]Findlay I. Inhibition of ATP-sensitive K+ channels in cardiac muscle by the sulphonylurea drug glibenclamide. J Pharmacol Exp Ther 1992; 261(2): 540-545.
  • [9]Nichols CG, Ripoll C, Lederer WJ. ATP-sensitive potassium channel modulation of the guinea pig ventricular action potential and contraction. Circ Res 1991; 68(1): 280-287.
  • [10]Kecskemeti V, Balogh I. The role of platelet-activating factor (PAF) antagonists and nitric oxide in cardiac actions of PAF.Electrophysiological and morphological study. J Physiol Pharmacol 2000; 51:723-735.
  • [11]Hoffman BF, Feinmark SJ,Guo SD. Electrophysiologic effects of interactions between activated canine neutrophils and cardiac myocytes. J Cardiovasc Electrophysiol 1997; 8:679-687.
  • [12]Flores NA, Goulielmos NV, Seghatchian MJ, Sheridan DJ.Myocardial ischaemia induces platelet activation with adverse electrophysiological and arrhythmogenic effects. Cardiovasc Res 1994; 28:1662-1671.
  • [13]Bkaily G, Wang S, Bui M, Stankova J, Rola-Pleszynski M.Modulation of cardiac cell Ca2+ currents by PAF. Blood Pressure 1996; 5 (Suppl 3): 59-62.
  • [14]Wahler GM, Coyle DE, Sperelakis N. Effects of platelet-activating factor on single potassium channel currents in guinea pig ventricular myocytes. Molecular and Cellular Biochemistry 1990;93:67-76.
  • [15]Iharra J, Morley GE, Delmar M. Dynamics of the inward-rectifier K+ current during the action potential of guinea pig ventricular myocytes. Biophys J 1991; 60: 1534-1539.
  • [16]Jurkiewicz NK, Wang J, Fermini B, Sanguinetti MC, Salata JJ.Mechanism of action potential prolongation by RP 58866 and its active enantiomier terikalnt. Block of the rapidly activating delayed rectifier K+ current, IKr1. Circ 1996; 94:2938-2946.
WanfangData CO.,Ltd All Rights Reserved
About WanfangData | Contact US
Healthcare Department, Fuxing Road NO.15, Haidian District Beijing, 100038 P.R.China
Tel:+86-010-58882616 Fax:+86-010-58882615 Email:yiyao@wanfangdata.com.cn