Effects of the calcium channel activator Bay K 8644 on general anaesthetic potency in mice.

1. The effects of the calcium channel activator, Bay K 8644, on the anaesthetic potencies of ethanol, argon and pentobarbitone were examined in mice. 2. Bay K 8644, at 1 mg kg-1 i.p., significantly antagonized the general anaesthetic potencies of ethanol and argon, but at 5 and 10 mg kg-1 this compound increased the general anaesthetic potency of these drugs. 3. At doses of 1, 5 and 10 mg kg-1 Bay K 8644 antagonized the anaesthetic effects of pentobarbitone. Bay K 8644, at the highest dose used, did not alter the brain concentrations of pentobarbitone or the blood concentrations of ethanol. 5. The effects of the different doses of Bay K 8644 on the actions of ethanol and of argon are compatible with the known partial agonist properties of this compound on calcium channels in vitro. 6. The actions of Bay K 8644 on the anaesthetic effects of pentobarbitone suggests that specific interactions may be involved in the anaesthetic actions of this compound.