[Effect of medullary chemosensitive structures on vascular neurogenic tonus].

In anesthetized cats, blockade of the intermediate chemosensitive area (area "S") of the ventral medulla by means of local cooling to 20-22 degrees C induced drop of arterial blood pressure by 22% as well as of the perfusion pressure in hind-limb skin-muscular and muscular preparations by 24% and 12%, resp. Analogous cooling of the caudal chemosensitive area (area "L") increased the BP by 6% as well as the perfusion pressure. Decentralizing of the hind-limbs prevented the perfusion pressure changes but did not affect the BP shifts. Raise of the temperature in the "S" area up to 41 degrees C increased both the BP and the perfusion pressure. Functional heterogeneity and role of the above chemosensitive areas in modulation of neurogenic vascular tone, are discussed.