Descending spinal pathways mediating pressor responses of cerebral origin

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Abstract
Blood pressure rises elicited by electrical stimulation of foci on the anterior sigmoid gyri of the cat''s cerebral cortex are abolished by complete transection of the spinal cord at the 6th cervical level; following the transection the arterial pressure baseline falls. Intraven. admn. of dibenamine-HCl acts similarly to cord transection. Stimulation of the brain with the Brief Stimulus Therapy Apparatus (Offner) through a pair of frontally-placed percutaneous electrodes evokes large, transient pressor responses. Following complete spinal cord transection at C6 or intraven. admn. of dibenamine-HCl, brain stimulation with the BST apparatus results in a fall of blood pressure and reduction in heart rate, eliminated by bilateral vagotomy. Following acute or chronic hemisections of the spinal cord at the lower cervical level, stimulation of the cortical focus contralateral to the cord lesion consistently resulted in elevations of blood pressure 20-60 mm. Hg less than those produced by stimulation of the ipsilateral cortical focus. From these expts. it may be concluded that the descending pressor pathway from the frontal lobe runs bilaterally in the spinal cord and that most of the fibers in the descending pressor pathway from the cerebral cortex have decussated above the level of the 6th cervical segment. Expts. involving various partial cord sections indicate that the descending pressor pathway in the cord at the lower cervical level runs in a relatively narrow zone at the junction of the dorsolateral and ventro-lateral funiculi.

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