[The participation of the neurons of the caudal ventrolateral area of the medulla oblongata in the cat in regulating vascular tonus]. / Uchastie neironov kaudal'noi ventrolateral'noi oblasti prodolgovatogo mozga koshki v reguliatsii sosudistogo tonusa.

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.

[Neurohistologic and histochemical characteristics of Loeschke's zone of the medulla in the cat]. / Neirogistologicheskaia i gistokhimicheskaia kharakteristiki zony Leshke prodolgovatogo mozga u koshek.

Neuronal organization and transmitter characteristics of chemosensitive area on the ventral medulla surface (zone L) of the cat were studied using neurohistological and histochemical methods. Neurons of different shape and size are heterogeneously distributed in zone L. They are concentrated mostly at the level of the hypoglossal nerve root, their number decreasing in the rostral and caudal directions. Negligible part of zone L neurons is choline- and monoaminergic, whereas the majority of neurons appears to release other transmitters. Cholinergic and noncholinergic cholinoceptive neurons as well as neurons sensitive to catecholamines and serotonin, are found in zone L. The conclusion is made that catecholamine-, serotonin- and cholinergic fibres found in zone L may be of local origin or run from other structures.