title: [Effects of nitrous oxide and isoflurane on the L-type calcium current of rabbit ventricular myocytes and their modulation by beta-adrenoceptor stimulation].
abstract: BACKGROUND
  We compared the effects of nitrous oxide (N2O) plus isoflurane with equianesthetic isoflurane alone on the L-type calcium current (I(Ca,L)), and also investigated their modulation of beta-adrenoceptor stimulation.
  
  
  METHODS
  I(Ca,L) was recorded from enzymatically isolated rabbit ventricular myocytes using the whole-cell patch clamp technique. Ventricular myocytes were exposed to prepluses of -40 mV from a holding potential of -80 mV and then to +50 mV in 10 mV increments and thereafter the depolarization pulses that acquire peak currents were applied every 10 seconds. The changes in I(Ca,L) were measured in exposure to experimental gases of 1 MAC:1) 0.5% isoflurane and N2O:O2 (2:1) (I-N20) and 2) 1.15% isoflurane and N2:O2,(2:1) (I-N2).
  
  
  RESULTS
  I-N2O and I-N2 depressed the peak I(Ca,L) by 15.6 +/- 9.2 and 14.6 +/- 8.1%, respectively. In the presence of 1 microM isoproterenol or 10 microM forskolin, the depression by I-N20 was significantly suppressed, but not by I-N2.
  
  
  CONCLUSIONS
  The results show that I-N2O and I-N2 depressed I(Ca,L) to a similar degree without beta-adrenoceptor stimulation. The depression by I-N2O, however, was modulated by beta-adrenoceptor stimulation. Beta-adrenoceptor stimulation was thus found to modulate the effect of N2O combined with isoflurane rather than equianesthetic isoflurane alone.
authors: Department of Anesthesiology, Juntendo University School of Medicine, Tokyo.
authors: Liu
authors: L
authors: Fan
authors: Seijiro
authors: S
authors: Sonoda
authors: Makino
authors: M
authors: Watanabe
authors: Hiroto
authors: H
authors: Tsujikawa
authors: Takao
authors: T
authors: Okada
authors: Kinya
authors: K
authors: Nishimura
authors: Kenji
authors: K
authors: Takamori
authors: Hideoki
authors: H
authors: Ogawa
authors: Eiichi
authors: E
authors: Inada
authors: Toyoki
authors: T
authors: Kugimiya
mesh_terms: D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D020746:Calcium Channels, L-Type / Q000187:drug effects*; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D004338:Drug Combinations; D006352:Heart Ventricles / Q000166:cytology; D007530:Isoflurane / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology; D032383:Myocytes, Cardiac / Q000187:drug effects*; D009609:Nitrous Oxide / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D011817:Rabbits; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*
chemical_list: D000777:Anesthetics; D020746:Calcium Channels, L-Type; D004338:Drug Combinations; D011943:Receptors, Adrenergic, beta; D005576:Colforsin; D007530:Isoflurane; D009609:Nitrous Oxide; D007545:Isoproterenol