Control of cerebral vascular smooth muscle during general anaesthesia.
The effects of some general anaesthetics, for example thiopentone, Althesin (alphaxalone + alphadolone) and ketamine, on cerebral vascular smooth muscle are those which would be expected from their metabolic actions. With other anaesthetics, mainly those administered by inhalation, and especially the volatile agents, cerebral blood flow increases in excess of the metabolic activity, which is usually depressed to varying degrees. During general anaesthesia with any of these agents, responses to changes in arterial Pco2 or blood pressure are maintained. Furthermore, when seizure activity occurs during enflurane administration, there is a flow response to the associated metabolic stimulation. The time course of the flow response to the metabolically depressant drug Althesin has been measured in baboons and shown to be very rapid. Wtih this drug cerebrovascular resistance begins to increase within 2 s of its arrival in the brain. This rapid flow change occurs also after sympathetic denervation. Extracellular fluid pH of the cortex does not alter until after the initiation of the vascular smooth muscle response.
D000530:Alfaxalone Alfadolone Mixture; D000768:Anesthesia, General; D000818:Animals; D001794:Blood Pressure; D001921:Brain / Q000378:metabolism; D002245:Carbon Dioxide / Q000097:blood; D002536:Cerebral Arteries / Q000187:drug effects*; D002560:Cerebrovascular Circulation / Q000187:drug effects; D004569:Electroencephalography; D005110:Extracellular Space; D000882:Haplorhini; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007649:Ketamine; D009130:Muscle, Smooth / Q000187:drug effects*; D010215:Papio; D010313:Partial Pressure; D013874:Thiopental; D014655:Vascular Resistance / Q000187:drug effects
D002245:Carbon Dioxide; D007649:Ketamine; D000530:Alfaxalone Alfadolone Mixture; D013874:Thiopental