The effects of decerebration on the reflex response to pulmonary vein distension.

1. A method is described for the decerebration of dogs using high frequency coagulation. Animals made decerebrate by this method showed a slowing of the heart rate and a decrease in arterial pressure.2. Distension of the pulmonary vein-left atrial junctions by the inflation of small balloons caused an increase in heart rate in intact and decerebrate dogs. The magnitude of the response was not significantly different in the two states.3. The increase in heart rate caused by pulmonary vein distension was shown to be a reflex. It was significantly reduced by injection of propranolol both before and after decerebration. Cervical vagotomy always prevented any response.4. The similarity of the responses before and after decerebration suggests that structures rostral to the superior colliculus are not required for the appearance of the full reflex effect.5. The magnitude of the response remaining after administration of propranolol raised the question of the efficacy of propranolol as a beta-blocking agent in this experimental situation, or alternatively suggests the possibility of the existence of an efferent vagal component to the reflex response.