Olcese R, Usai C, Maestrone E, Nobile M
Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas.
Anesth Analg. 1994 May;78(5):955-60. doi: 10.1213/00000539-199405000-00021.
The action of propofol on voltage-gated calcium channels was investigated in cultured dorsal root ganglion neurons from chick embryos. The Ca2+ current was measured by using the patch-clamp technique in whole cell configuration. Low-voltage-activated (LVA) and high-voltage-activated (HVA) Ca2+ currents were selected by means of appropriate stimulation protocols. Propofol (0.3 mM) inhibited the LVA T-type current by 80% (P < 0.001). The same concentration of propofol reduced the HVA Ca2+ current with a high variability (10%-75%). The inactivation time constant of the HVA current was also shortened to 50% by propofol. omega-Conotoxin and nifedipine were used to discriminate between the HVA N- and L-type current components. Only the L-type component was strongly depressed (75%) by propofol (P < 0.001); different effects on the HVA current might, therefore, reflect different percentages of L- and N-type channels in neurons. We conclude that propofol inhibits the T-type and L-type components of the Ca2+ current. This inhibition may play a role in the cardiovascular side effects clinically observed.
在鸡胚背根神经节培养神经元中研究了丙泊酚对电压门控钙通道的作用。采用全细胞模式的膜片钳技术测量Ca2+电流。通过适当的刺激方案选择低电压激活（LVA）和高电压激活（HVA）Ca2+电流。丙泊酚（0.3 mM）使LVA T型电流抑制80%（P < 0.001）。相同浓度的丙泊酚使HVA Ca2+电流降低，变化很大（10%-75%）。丙泊酚还使HVA电流的失活时间常数缩短至50%。使用ω-芋螺毒素和硝苯地平区分HVA N型和L型电流成分。只有L型成分被丙泊酚强烈抑制（75%）（P < 0.001）；因此，对HVA电流的不同影响可能反映了神经元中L型和N型通道的不同比例。我们得出结论，丙泊酚抑制Ca2+电流的T型和L型成分。这种抑制可能在临床上观察到的心血管副作用中起作用。
