title: Stimulation by melittin of Na+-Ca2+ exchange current in ventricular myocytes of guinea pigs.
abstract: OBJECTIVE
  To study the mechanism of calcium overload induced by melittin in myocytes.
  
  
  METHODS
  Whole cell patch-clamp technique was applied for recording the currents.
  
  
  RESULTS
  Mel 0.05, 0.1 micromol/L increased the peak amplitude of I(Na) (nA) from -2.1+/-0.8 to -3.2+/-1.0 (n=7, P < 0.05) and -3.7+/-1.5 (n=7, P < 0.05) respectively at testing potential of -40 mV. Mel 0.05, 0.1, 0.2 micromol/L had no significant effect on I(Ca), but enhanced I(Na-Ca) (pA) from 53+/-21 to 427+/-256 (n=5, P < 0.05), 349+/-147 (n=5, P<0.01) and 320+/-97 (n=5, P < 0.05) respectively at a testing potential of +50 mV.
  
  
  CONCLUSIONS
  The stimulating effect of Mel on I(Na-Ca) rather than the effect on I(Ca) contributes to the calcium overload of myocytes.
authors.affiliation: Department of Pharmacology, School of Pharmacy, Fudan 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: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: P
authors.initials: P
authors.lastname: Zheng
authors.forename: M H
authors.initials: MH
authors.lastname: Jiang
authors.forename: Z N
authors.initials: ZN
authors.lastname: Zhou
mesh_terms: D000818:Animals; D002469:Cell Separation; D004594:Electrophysiology; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000166:cytology; D008555:Melitten / Q000494:pharmacology*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D019831:Sodium-Calcium Exchanger / Q000187:drug effects / Q000378:metabolism*
chemical_list: D019831:Sodium-Calcium Exchanger; D008555:Melitten