[The role of endogenous bioregulators in formation of cardiogenic reflex effects on circulation].

The possible role of endogenous endothelium-derived bioactive substances in organization of cardiogenic depressor reflexes under cardiac receptor stimulation (by veratrine and bradykinin) was investigated in acute experiments on anesthetized rats. The results have shown that endothelium-derived bioactive substances take part in forming of the cardiogenic depressor reflex humoral components of nervous response or nervous modulators. These data contribute to understanding of the role of endogenous endothelium-derived bioactive substances (prostacyclin) and different NOS isoforms in mechanisms of depressor reflex development and species differences in their involvement in reflex vasomotor reactions.

[Role of nitric oxide in the mechanisms of formation of reflex vasomotor responses].

This review focuses on modem data concerning the role of nitric oxide (NO) in the mechanisms of vasomotor regulation. On the background of the literature data and own experimental results, we have discussed some questions of NO integration into transmission of impulses in central and autonomic nervous system under condition of realization of cardiogenic and sinocarotid pressor and depressor reflexes, reflectory vasomotor responses formation under acute myocardial ischemia. According to literature and own functional and morphological data we suggest species differences in NO participations in mechanisms of reflex self--regulation of circulation.

[Central neuronal pathways in the Bezold-Jarisch reflex in rats].

The distribution of the Fos-immunoreactive (Fos-ir) and NADPH-diaphorase-positive/NOS-containing neurons in the medulla and thoracic spinal cord in rats was studied after the veratrine injection into v. jugularis ext. followed by reproduction of the Bezold-Jarisch reflex. Fos-ir neurons were found in the nucleus tractus solitarius (Sol), coudoventrolateral (CVL) and rostroventrolateral (RVL) areas, intermediate reticular nucleus (IRt), and lateral paragiganrocellular nucleus (LPGi) of the medulla. The intensity of c-fos expression was as follows: Sol > CVL > RVL > LPGi. The intensity of NADPH-diaphorase reactivity was manifested in the following sequence: Sol > IRt > LPGi > RVL. In comparison to sham-operated animals, application of veratrine is associated with a statistically significant increase (P < 0.01) of the mean number of Fos-ir neurons in the Sol and CVL, but not in the RVL. Double-labelling (Fos + NA DPH) was found in a small number (about 2%) of neurones in the Sol, IRt and LPGi. In the thoracic spinal cord Fos-ir neurons were predominantly detected in the superficial layers of the dorsal horn, area around the central canal and the intermediate lateral or medial nuclei (IMl and IMM), where NOS-containing neurons in the thoracic spinal cord were accumulated. Received data show that signals arising from the veratrine-activated cardiopulmonary afferents activate neurons of the Sol and CVL that together with the RVL are incorporated into neuronal circuits for generation of the Bezold-Jarisch reflex. In the medulla NOS-containing neurons activated by input from cardiopulmonary receptors can contribute to the enhancement of cardioprotective depressor reflexes in the rats.

[Characteristics of distribution of nitric oxide synthase containing neurons in the medullary cardiovascular centers of dogs and rats]. / Osoblyvosti rozpodilu neironiv, shcho mistiat' syntazu oksydu azotu v meduliarnykh sertsevo-sudynnykh tsentrakh sobak i shchuriv.

The aim of the study was to characterize species-related differences in the distribution of nitric oxide synthase (NOS)-containing neurons in the medullary structures of dogs and rats involved in the regulation of the sympathetic or parasympathetic drives. Two main results have been obtained, namely: (i) the average number of NOS-containing neurons in the dorsomedial and ventrolateral medulla per section in dog was larger than that in rat, while the density of the positive cells in the both regions in dog was less than that in rat. (ii) Within the dorsal motor nucleus of vagus a lot of NOS-containing cells (preganglionic vagal neurons) were observed only in dog. Differences in the distribution of NO-generating neurons in the medullary cardiovascular centers, and heterogeneity in the basal level of NO release may contribute to the peculiarities of the hemodynamic responses induced by NOS inhibitors in these species.

[Role of biologically active substances in the formation of cardiogenic reflex effects on circulation]. / Rol' biolohichno aktyvnykh rechovyn u formuvanni kardiohennykh reflektornykh vplyviv na krovoobih.

Analysis of the literary and own authors data about the participation some endogenous bioregulators (prostacyclin, bradykinin, nitric oxide) in the cardiogenic depressor reflexes formation is represented in this review. Possibility of chemosensitivity of the vagal afferent fibers for this substances and its role in the formation of cardiogenic effects on circulation is discussed.

[The role of endothelium-dependent factors in realizing cardiogenic reflexes under normal and pathological conditions]. / Doslidzhennia roli endoteliizalezhnykh faktoriv u realizatsiï kardiohennykh refleksiv za normal'nykh i patolohichnykh umov.

We have investigated the role of NO-dependent mechanisms in the realization of cardiogenic reflexes (pressor and depressor) during the action of veratrin and serotonin on cardiac receptors, adrenergic changes of the myocardial contractile activity or the short-term period of myocardial ischemia on anaesthetized dogs cats and rats. NO take place in the development of cardiogenic depressor reflexes and decreases pressor reflexes from the cardiac receptors in dogs. Specific characteristics of these influences were asserted: the depressor reflexes decrease after systemic inhibition of NOS by L-NNA in dog but they are increased or are not altered in rats. The depressor reaction in rats diminished after inhibition of nNOS performing by 7-nitroindazole. We affirm that NO-dependent influences have a compensatory effect in the course of acute alterations of the coronary blood flow and our statement concerning the advantageous role of NO-dependent mechanisms in the realization of self-regulatory reactions of circulation that connected with vagus nerve.