[The participation of the neurons of the caudal ventrolateral area of the medulla oblongata in the cat in regulating vascular tonus].

Inhibition of the separate neuronal groups located in the caudal ventrolateral part of the cat medulla at different depths from the brain surface is followed by the development of unidirectional cardiohemodynamic reactions. Microinjection of 30 nl of 0.1 M solution of glycine in the chemosensitive area "L" at a depth not more than 700 microns is followed by an increase of the arterial pressure to 160-225%, presumably, due to enhancement of the total peripheral vascular resistance, the cardiac output and heart rate change insignificantly. Such direction of hemodynamic changes is due to activation of the neurogenic vascular tone. Data obtained give the possibility to appreciate investigated neuronal groups as tonically active, with an inhibitory influence on sympathetically activation of the vessels. The method of the retrograde axonal transport of HRP was used to determine monosynaptic projections from different neuronal pools of the caudal ventrolateral part of medulla to the subsolitary district of the reticular formation. The data obtained contribute to comprehension of mechanisms of interaction in the dorsal and ventral areas of the medulla participating in the regulation of the vascular tone.