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Biomedical subjects

V I Ovsiannikov

Publications and source records attributed to V I Ovsiannikov.

At least 19 recordsLinked to original sources
PubMed2005

[Mechanisms of serotonin effect on motility of ileocaecal zone in alert rabbits].

I.V. administration of serotonin (2 mg kg(-1)) to alert rabbits changed the ileal, caecal, and colon motility including excitatory and inhibitory components. Initial rise of contractile activity was quickly replaced by its diminishing followed by a longer enhancement of the motility, and then by the final, inhibitory, phase. Under blockade of beta1- and beta2-adrenoreceptors with propranolol inhibition of ileal and caecal contractile activity with serotonin was preserved, the effect of circulating catecholamines on beta-adrenoreceptors of smooth muscle cells seems to be excluded as a cause of the serotonin inhibitory effect. In conditions of blockade of pre- and postsynaptic alpha-adrenoreceptors with phentolamine, there was no significant diminishing of the contractile activity in the ileo-caecal zone below the initial level induced by serotonin in control experiments. Intensification of the ileo-caecal zone contractile activity under the effect of serotonin persisted in conditions of blockade of muscarinic cholinoreceptors and was proceeding with participation of non-cholinergic excitatory mechanism.

Adrenergic alpha-Antagonists↗
PubMed2005

[Mechanisms of inhibition of the contractile activity in the ileo-caecal zone in rabbits under psychogenic stress].

In experiments on unanaesthetized rabbits, myoelectric activity (contractile activity index) of distal ileum, caecum, and proximal colon in two sites was studied under stress induced by fastening a rabbit to the table in supine position. The stress caused sharp decrease (up to complete disappearance) of the contractile activity in all studied compartments of the ileocaecal intestine with partial or complete restoration after release of the animal. Nonselective blockade of pre- and postsynaptic alpha-adrenoceptor with dihydroergotoxin abolished the initial component of the specified inhibitory response. The latter was caused by "adrenergic inhibition" as a result of action of catecholamines circulating in blood on inhibitory smooth muscle alpha-adrenoceptor. Against the background of muscarinic cholinoceptor blockade, the stressor inhibition of ileocaecal contractile activity observed in control experiments was completely preserved. The periods of supression of ileoceacal contractile activity under stress resistant to blockade of alpha-, beta-adrenoceptor and muscarinic cholinoceptor, are caused by the mechanism of "nonadrenergic noncholinergic inhibition", which is realized at the expence of activation of the enteric inhibitory neurones.

Adrenergic alpha-Antagonists↗
PubMed2002

[Mechanism of the serotonin effect on motility of the duodenum, ileum, and jejunum in awake rabbits].

I. v. administration of serotonin to alert rabbits produced a phasic change of contractile activity of duodenum, ileum, and jejunum including excitatory and inhibitory components. It is shown that stimulation of the small bowel motility is caused by serotonin activation of non-cholinergic excitatory mechanism with participation of effector cholinergic neurones. The initial suppression of the motility is caused by participation of nonadrenergic noncholinergic inhibitory mechanism, and the secondary inhibition of contractile activity of a small bowel with serotonin has an adrenergic nature.

Adrenergic alpha-Antagonists↗
PubMed2001

[Non-adrenergic mechanisms of inhibition of the contractile activity of the cat small intestine by histamine, bradykinin, and met-enkephalin].

I. a. histamine and bradykinin caused both an activation and an inhibition of jejunal contractile activity. The inhibitory effect was preserved after blockade of muscarinic cholinoreceptors, alpha- and beta-adrenoceptors, and abolished with the nicotinic cholinoceptor blockade. Metenkephalin inhibited the jejunal contractile activity after first activating it. The inhibitory effect of the peptide was preserved after blockade of alpha- and beta-adrenoceptors as well as the nicotinic cholinoceptors. The data obtained suggest that the non-adrenergic inhibitory effect of metenkephalin on intestinal contractions was the result of its depressing action on motor cholinergic neurons, whereas the inhibition of intestinal contractile activity with histamine and bradykinin resulted from their activating action on cholinergic interneurons which activate non-adrenergic inhibitory neurons through nicotinic cholinoceptors.

Adrenergic alpha-Antagonists↗
PubMed2001

[Stress-induced inhibition of the ileal, caecal, and colonic contractile activity in rabbits].

In alert rabbits, immobilisation stress decreased the spike burst rate and amplitude in ileum, caecum, and colon for 20 min. Following beta-adrenoceptor blockade, the contractile activity suppression was aggravated. The stress seems to lead to suppression of the ileal, caecal, and colonic contractile activity for up to 40 min which is unrelated to adrenergic inhibition of the smooth muscle activity mediated by beta-adrenoceptors.

Action Potentials↗
PubMed1999

[Myoelectrical activity in the stomach during ulcerogenic exposure in rabbits].

Stomach myoelectrical activity changed the slow wave frequency and spike discharges under the effect of experimental injury in rabbits. High-amplitude fluctuations named the "injury potentials" appeared. Bensohexonium prevented the changes as well as ulceration. Metacin combined with proserin accelerated healing of the ulcer and the rate of stomach myoelectrical activity.

Animals↗
PubMed1998

[Adrenergic mechanism of the stimulation of the small intestine motor activity].

Myoelectrical activity of the duodenum and ileum was recorded in rabbits with implanted electrode. Acute haemorrhage caused either elevation or reduction of the firing rate, the responses being abolished with a combined blockade of alpha- and beta-adrenoreceptors. Beta-adrenoreceptors agonist isoproterenol resulted in a biphasic (decrease-increase) change of the myoelectrical activity which could be abolished with blockade of beta-adrenoreceptors. The character of the small intestine motor responses to acute haemorrhage and isoproterenol infusion depended on the initial level of the intestinal contractile activity. The findings suggest that catecholamines induce a small intestinal motor effect via stimulation of both inhibitory adrenoreceptors and excitatory presynaptic adrenoreceptors.

Action Potentials↗
PubMed1996

[I.P. Pavlov at the Imperial Institute of Experimental Medicine and his contribution to digestive physiology].

The paper presents the previously unknown facts of Pavlov's scientific life, which covers his work at the Institute of Experimental Medicine. It also reviews the studies made at Pavlov's laboratory whose results were combined by I. P. Pavlov in his book "Lectures on the Work of Major Digestive Glands" in 1887. It also contains the data obtained before 1904 when I. P. Pavlov was awarded the first Russia's Nobel prize for his studies of digestive physiology.

Academies and Institutes↗
PubMed1996

[The integration of neuromediators and hormones in the digestive system].

The review gives the current data on the gastrointestinal regulatory systems, characterizes the functional links and mechanisms of neurotransmitter and hormonal factors, summarizes the data on the mechanisms of the coupling of the sympathoadrenal system with the cholinergic neurons in the enteric nervous system.

Animals↗
PubMed1996

[From Pavlov's recording of time and conditioned reflexes to the chronophysiology of human nutrition].

That I. P. Pavlov understood how important to record the time factor allowed him to anticipate the chronobiological approach in physiology. As compared to the conditioned reflexes, the body's biological rhythms appeared to have a deeper basis - chronomes coded in the genes. The authors comparatively characterize the homeostatic approach used by I. P. Pavlov and the chronobiological approach proposed by F. Halberg both for biology and medicine.

Animals↗
PubMed1994

[The role of the beta-adrenoreceptors in the manifestation of the peristaltic reflex].

Distension of the ileal segment was shown to induce its contraction in isolated portion of the cat ileum, the response being abolished by M-cholinergic blockade and preserved after N-cholinergic blockade. Blockade of the beta-adrenoreceptors or their stimulation did not affect the peristaltic reflex. The findings suggest that the excitatory beta-adrenoreceptors are not directly involved in the first phase of peristaltic reflex.

Animals↗
PubMed1993

[The excitatory effects of stimulating the presynaptic beta-adrenoreceptors of the ileum in unanesthetized rabbits].

Experiments were performed on unanaesthetized rabbits. It has been shown that beta-adrenergic stimulation by isoprenaline can lead to decreasing as well as increasing of spike activity of the ileum. Pretreatment with propranolol completely prevented both effects of isoprenaline. Administration of isoprenaline both during M-cholinergic and N-cholinergic blockades resulted in decreased spike activity alone. These results suggest that isoprenaline-induced increase in spike activity is mediated by excitatory beta-adrenoceptors localized on the presynaptic cholinergic interneurons of the enteric nervous system.

Action Potentials↗
PubMed1993

[The role of adrenoreceptors in the manifestation of the smooth-muscle reactions of the pyloric sphincter and small intestine to acute blood loss].

Acute blood loss evoked an increase in the spike activity of the pyloric sphincter' smooth muscles, those of the duodenum and ileum. No such effect was found in joint blockade of alpha- and beta-adrenoreceptors. The increase in the spike activity seems to be due to an effect of endogenous catecholamines upon activating alpha- and beta-adrenoreceptors of the pyloric sphincter, duodenum and ileum.

Action Potentials↗