EFFECT OF ANÆSTHETICS ON BARORECEPTOR REFLEXES

¹ The Department of Physiology, University of Edinburgh

1. The carotid sinus in cats, isolated from the rest of the circulation but with its nerve supply intact, was perfused with ether and chloroform in various concentrations in buffered Tyrode solution. The increased sensitivity of the baroreceptors which these anæsthetics produce is great enough to cause reflex changes in systemic blood pressure and in heart rate under these conditions.

2. Perfusion with high concentrations of ether (300 mg. per cent W/V) and chloroform (100 mg. per cent W/V) rapidly inactivated the baroreceptors.

3. The fall in blood pressure produced by the sudden inhalation of ether, chloroform and trichlorethylene was recorded in cats before and after cutting the baroreceptors. The fall of pressure was greatly reduced in 7 of the 9 experiments by baroreceptor denervation, and it was concluded that increased sensitivity of the baroreceptors plays an important part in producing the cardiovascular changes that follow the rapid inhalation of these volatile anæsthetics.

Note:

We are grateful to Professor D. Whitteridge, F.R.S., for providing facilities for the work and for his encouragement.