An intense hypotensive response evoked by medullary stimulation in the pyramidal cat

¹ Masonic Medical Research Laboratory, Utica, New York

In the pyramidal cat, point stimulation of the ventral medial portion of the dorsal medulla can result in an intense hypotensive response which may result in death of 10% of the trials or in a prolonged depression of systemic pressure in the remainder. This response was found to result from a cholinergically mediated vasodilatation in combination with a prolonged inhibition of vasoconstrictor tone. The dual hypotensive response does not result from random stimulus spread within the medulla but is rather a distinct vasomotor response. The intensity and duration of the phase of vasoconstrictor inhibition would appear to be a factor in determining the full development of the lethal response.

Key Words: medullary vasomotor control • cholinergic vasodilatation • blood pressure

Submitted on July 30, 1964