Effect of thiopentone, etomidate and propofol on carotid body chemoreceptor activity in the rabbit and the cat.

The response of the carotid body chemoreceptors to intracarotid administration of thiopentone, etomidate and propofol was tested in the rabbit and cat. Thiopentone 3-6 mg min-1 and etomidate 300-600 micrograms min-1 were mildly excitatory, shifting the oxygen and carbon dioxide response curves upwards. Propofol 1.5-3.0 mg min-1 was a potent chemodepressant and abolished discharge at PaO2 values greater than 8 kPa. Prolonged infusion of propofol at higher rates (6 mg min-1) abolished the response to hypoxia completely. The significance of these results is discussed in relation to the known ventilatory effects of the three anaesthetics.