[Participation of different groups of the afferent fibers of the depressor nerve in regulating blood pressure]. / Ob uchastii razlichnykh grupp afferentnykh volokon depressornogo nerva v reguliatsii arterial'nogo davleniia.

A-fibes were found to participate mainly in spontaneous discharges of the depressor nerve synchronous with the heart rhythm in cats. A raise in the blood pressure induced a considerable activation of C-fibes.

[Level at which baroreflex sympatho-inhibitory effects are achieved]. / Ob urovne realizatsii baroreflektornykh simpatoingibitornykh vliianii.

The interaction between the descending sympathoexcitatory "vasomotor" and the inhibitory baroreceptor systems was studied in cats. The spontaneous activity and reflex discharges of the identified bulbar sympathoexcitatory neurons were unaffected during the stimulation of baronlferents and the elevation of the arterial blood pressure. It was found that baroreceptor impulses inhibit the spinal interneuron system which take part in transmission of descending sympathoexcitatory influences.

[Specialization of the descending sympatho-activating pathways of the dorsolateral funiculus of the spinal cord]. / O spetsializatsii niskhodiashchikh simpatoaktiviruiushchikh putei dorso-lateral'nogo kanatika spinnogo mozga.

In anesthetized curarized cats the degree of specialization of the descending sympathoexcitatory axons which activate sympathetic preganglionic (vasomotor) B2--neurons of the lateral horn, was studied. These sympathoexcitatory fibers with conduction velocity of 4.0--8.9 m/sec activate especially onlg the sympathetic B2--units of the spinal cord. Other neurons (phrenic and intercostal mofoneurons and sacral parasympathetic preganglionic neurons) are activated by different groups of descending fibers with conduction velocity greater than that of descending sympathoexcitatory fibers.

[Identification and study of sympathoactivating neurons of the medulla oblongata]. / Identifikatsiia i issledovanie simpatoaktiviruiushchikh neironov prodolgovatogo mozga.

The neurons with descending axons which activate the lateral horn sympathetic preganglionic (vasomotor) neurons were searched in the lower brain stem of the cat. Localization of these sympathoactivatory neurons in the limit zone of medulla was outlined by means of scanning stimulation. The identification of single bulbar sympathoactivatory neurons was based on the recording of their antidromic discharges elicited by stimulation of descending sympathoactivatory pathways with conduction velocity about 4--8.9 m/s in the dorsolateral funiculi of the cervical spinal cord. The neurons studied have a very low frequency spontaneous discharges (0.1--1.0 imp/s) unrelated with cardiac and respiratory cycles. The alterations of spontaneous discharge frequency were in strict correlation with pressor phases of Maer waves and pressor reflex reactions. The inhibitory effects of the baroreceptor nerve stimulation on spontaneous and elicited discharges of these neurons were never seen. A possible role of the sympathoactivatory neurons identified as an output elements of the bulbar "vasomotor" centre is discussed.

[Further study of the descending sympathoactivating pathways of the dorsolateral funiculus of the spinal cord]. / Dal'neishee issledovanie niskhodiashchikh simpatoaktiviruiushchikh putei dorso-lateral'nogo kanatika spinnogo mozga.

The localization and conduction velocities of descending pathways which activate the different groups of sympathetic preganglionic nerons were studied in the cat cervical spinal cord. Certain evidences have been obtained that the fibres located near the dorsal surface of the dorsolateral funiculi with conduction velocities about 24--29 m/sec. can activate the ventral horn preganglionic neurons monosynaptically. In contrast to previous ideas, the sympathetic preganglionic neurons of the lateral horns seem to be activated not by different but by a single group of descending fibers with the conduction velocity 4--8.9 m/sec and localization in more ventral portions of the dorsolateral funiculus. The transmission from these fibers to the sympathetic preganglionic neurons of the lateral horns occurs in two ways: oligosynaptically (probably, disynaptically) and polysynaptically through a more complicated interneuronal chain. The sympathetic preganglionic neurons with unmyelinated axons, localized in the intermediate zone, for the first time were shown to be activated polysynaptically, probably via the same ways as the lateral horn neurons.