Background:To determine if the decrease in blood pressure produced by propofol, thiopental, and etomidate is associated with changes in the peripheral serotonin system.
Material/Methods: 24 patients undergoing induction for general anesthesia with propofol, thiopental, and etomidate (8 with each drug) were studied. Measurements of heart rate (HR), systolic blood pressure (SAP), platelet aggregation induced by ADP, collagen, and adrenaline, 5HT aggravation of induced platelet aggregation, and platelet 5HT content were performed before induction, one minute, and three minutes after drug administration.
Results: HR did not change during induction, but SAP decreased significantly during induction with propofol and thiopental. Propofol produced no changes in platelet aggregation or platelet 5HT content. Thiopental inhibited all types of platelet aggregation and decreased 5HT platelet content. Etomidate inhibited only ADP platelet aggregation, increased 5HT aggravation of platelet aggregation, and decreased platelet 5HT content.
Conclusions: Decreased SAP during propofol induction appears not to be associated with changes in the peripheral serotonin system. Decreased SAP from thiopental is associated with stimulation of the peripheral serotonin system.

Keywords: anaesthetics, intravenous - propofol, intravenous - thiopental, intravenous - etomidate, serotonin - aggregation, serotonin - platelet content