抄録
Responses of the right cervical sympathetic nerve and the systemic arterial pressure to vertebral and carotid embolism were examined in rabbits anesthetized with α-chloralose and the following results were obtained:
(1) Vertebral embolism resulted in a marked rise of blood pressure, while carotid embolism resulted a fall.
(2) Hypertension produced by vertebral embolism was converted to hypotension by carotid embolism, whereas hypotension produced by carotid embolism to hypertension by vertebral embolism.
(3) Hypertension produced by vertebral embolism disappeared on administration of hexamethonium or tetraethyl-ammonium chloride immediately after the rise of blood pressure, whereas it became more marked following the administration of the latter after several minutes indicating increased circulating vasopressor substances. After administration of either hexamethonium or phenoxybenzamine, vertebral embolism caused only a slight rise in blood pressure.
(4) The action potentials of the cervical and renal sympathetic nerves increased usually at the onset of hypertension in vertebral embolism, whereas they decreased at the onset of hypotension in carotid embolism.
In conclusions, the increased sympathetic activity participated in hypertension produced by vertebral embolism, while the decreased sympathetic activity in hypotension produced by carotid embolism. It was supposed that sympathetic function was dominant in the portions supplied by the vertebral arteries, whereas sympathetico-inhibitory function in the portions supplied by the internal carotid arteires.
