title: Effect of melittin on potassium currents and action potential in ventricular myocytes of guinea pig.
abstract: OBJECTIVE
  To examine the effects of melittin (Mel), the major component of bee venom, on delayed rectifier K+ current (Ik), inward rectifier K+ current (Ikl) and action potential (AP) in guinea pig ventricular myocytes.
  
  
  METHODS
  Ik, Ikl, and AP were recorded using the whole-cell patch-clamp technique.
  
  
  RESULTS
  The action potential duration (APD) was shortened by Mel in a concentration-dependent manner. Mel 0.05, 0.1, 0.2 mumol.L-1 shortened APD50 from (520 +/- 55) to (459 +/- 91) (n = 5, P > 0.05), (385 +/- 102) (n = 5, P < 0.01), and (281 +/- 81) ms (n = 5, P < 0.01), respectively; and APD90 from (613 +/- 96) to (536 +/- 93) (n = 5, P > 0.05), (467 +/- 96) ms (n = 5, P < 0.01), and (354 +/- 95) ms (n = 5, P < 0.01), respectively. Mel increased the amplitude of Ik also in a concentration-dependent manner. Mel 0.05, 0.1, 0.2 mumol.L-1 increased Ik from (295 +/- 109) to (371 +/- 142) (n = 5, P < 0.05), (467 +/- 180) (n = 5, P < 0.05), (552 +/- 248) pA (n = 5, P < 0.05), respectively at testing potential of + 40 mV. But no significant effect of Mel on Ikl was observed at these concentrations.
  
  
  CONCLUSIONS
  Mel significantly increased Ik in a concentration-dependent manner which contributed to shortening of APD.
authors.affiliation: Department of Pharmacology, School of Pharmacy, State Key Laboratory of Medical Neurobiology, Shanghai Medical University, Shanghai 200032, China.
authors.forename: X M
authors.initials: XM
authors.lastname: Zhang
authors.forename: S
authors.initials: S
authors.lastname: Yang
authors.forename: X J
authors.initials: XJ
authors.lastname: He
authors.forename: P
authors.initials: P
authors.lastname: Zheng
authors.forename: M H
authors.initials: MH
authors.lastname: Jiang
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002469:Cell Separation; D006168:Guinea Pigs; D008555:Melitten / Q000494:pharmacology*; D009206:Myocardium / Q000166:cytology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects*; D016276:Ventricular Function
chemical_list: D015221:Potassium Channels; D008555:Melitten