The general anesthetic propofol inhibits transmembrane calcium current in chick sensory neurons.
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.
Olcese
R
R
Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas.
Usai
C
C
Maestrone
E
E
Nobile
M
M
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002642:Chick Embryo; D005727:Ganglia, Spinal / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D015742:Propofol / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D015742:Propofol