Abstract
(1) The role of the carotid sinus in regulation of the blood flow of the internal carotid artery was studied in rabbits anesthetized with Nembutal and immobilized with D-tubocurarine. The blood flow and the blood pressure of the internal carotid artery were measured with a heated thermocouple and pressure transducer, respectively.
(2) Despite a reduction in the blood pressure which was induced by a gradual clipping of the common carotid artery, a fairly constant blood flow was maintained, provided that the blood pressure did not fall below a certain value. The value was termed Cr. B. P.(critical blood pressure) for convenience and ranged from 46 to 96mm Hg.
(3) Section of the ipsilateral sinus nerve resulted in an elevation of Cr. B. P. from 46-96 to 75-110mm Hg. This indicates that the capacity for keeping the constant blood flow was considerably reduced by the nerve section. From these results it was inferred that some informations detected by the sinus contributed for the maintenance of a constant blood flow in the internal carotid artery. If this is accepted, it follows that the sinus plays a role as the flow monitor in regulation of the blood flow.
