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V I Sviriaev

Publications and source records attributed to V I Sviriaev.

8 recordsLinked to original sources
PubMed1992

[The vagotropic action of peptides isolated from the brain of hibernating susliks].

Dipeptide ASP-TYR extracted from the brain of hibernating squirrels was found to potentiate vagal effect on the cardiac rhythm, whereas pentapeptide neokyotorphin--to diminish it. In both cases the effect was due to an alteration of the tonic component's strength in the vagal chronotropic effect. The selective peptidergic modulation of the vagal effect on the cardiac rhythm suggests different physiological roles of the tonic and synchronizing components in regulation of the heart.

Animals↗
PubMedDate not supplied

[Isolation, structure and properties of new endogenous peptides].

Large scale isolation and determination of amino acid sequences of endogenous peptides from various biological sources (bovine brain and red bone marrow, siberian ground squirrel brain) were carried out. A number of earlier unknown peptides were identified, many of them showing distinct activity in vivo and/or in vitro. Analysis of more than 170 isolated peptide structures resulted in the hypothesis suggesting functional proteins, in particular hemoglobin, to serve also as a source of the peptide "background" which has its own biological significance. Further directions of investigating the endogenous peptide material are mapped. Its potential for developing diagnostics for somatic diseases is demonstrated on patients with CNS disorders.

Amino Acid Sequence↗
PubMedDate not supplied

[The hypometabolic effect of the blood plasma from a hibernating suslik Citellus undulatus. Neokyotorphin activates cardiac and respiratory activities in the suslik during arousal from hibernation].

The effect of intraabdominal injection of the blood serum from ground squirrels Citellus undulatus obtained at various stages of the baut has been studied on the level of oxygen consumption in albino mice. The strongest hypometabolic effect exhibited the blood plasma from animals at the beginning of the baut. The onset of baut was used in further experiments on C. undulatus for investigation of activating effects of neokiotorphin (Thr-Ser-Lys-Tyr-Arg) which was earlier found in the brain of the ground squirrel. It was shown that intraabdominal injection of this peptide to hibernating animals facilitates their arousal stimulating both the cardiac activity and respiration. The strongest effect was noted with neokiotorphin of [D-Ser] 2-modification which is more stable to proteolysis.

Animals↗
PubMedDate not supplied

[The cardiotropic, hypometabolic and hypothermic activity of peptide fractions from the tissues of hibernating cold-adapted animals].

From tissues of hibernating and active long-tailed ground squirrels and from the brain of cold-adapted Yakut horses, low molecular peptide fractions were obtained which, after injection to albino mice, decreased oxygen consumption and rectal temperature in them. The same fractions exhibited negative chrono- and inotropic effects on isolated hearts of ectothermic and endothermic animals. Fractions from the brain of ground squirrels and the brain of horse exhibited similar pattern of the activity. The activity of fractions was subjected to seasonal changes and depended on the degree of their purification. Provisional intracellular microelectrophysiological analysis of the effect of these fractions on the frequency and strength of contractions in isolated heart was made.

Adaptation, Physiological↗
PubMedDate not supplied

[Biologically active peptides isolated from the brain of hibernating ground squirrels].

More than 20 peptides have been isolated and sequenced from the brain of hibernating ground squirrel Citellus undulatus. Some of the isolated peptides were chemically synthesized and investigated for the spectrum of biological activity. One of the isolated peptides, neokyotorphin (Thr-Ser-Lys-Tyr-Arg), earlier known as a weak analgetic, is found to have a cardiotropic and thermoregulatory activity. Neokyotorphin activates in vitro voltage-dependent calcium and blocks ATP-dependent potassium currents in the frog atrial fibres. Intraperitoneal injection of this peptide in hibernating ground squirrels speeds up the arousal of animals increasing sharply the heart rate and oxygen consumption. Intraperitoneal and intranasal administrations of neokyotorphin in rats raises body temperature in thermoneutral conditions (26-28 degrees C) exerting no effects at low (4-6 degrees C) and high (31-32 degrees C) environmental temperatures. Another isolated peptide, Asp-Tyr, blocks the inward voltage-dependent calcium current in the frog atrial fibres and slightly increases the outward potassium current. Sulfated analogue of this dipeptide (aspartyl-O-sulfate-tyrosine) more effectively blocks the inward voltage-dependent calcium current in the frog atrial fibres and have no effects on the outward potassium current.

Amino Acid Sequence↗