[Variations in the effect of clonidine on arterial pressure in rats in the presence of various anesthetics].

The central hypotensive agent, clonidine (30 microgram/kg i.v.) has been injected in normotensive rats anesthetized with various agents. This dose of clonidine elicits usually a biphasic blood pressure response, i.e. a transient increase due to peripheral vasoconstriction, followed by a long lasting decrease. This has been observed in the animals anesthetized with pentobarbitone as well as with urethane. The hypotensive effect is abolished during chloralose, ketamine or Alfatésine anesthesia. These data emphasize that some anesthetics mays particularly modify the effects of centrally acting cardiovascular drugs.