Biomedical subjects

I P Ledneva

Publications and source records attributed to I P Ledneva.

4 recordsLinked to original sources

PubMed1990

[The effect of acetylcholine and serotonin on the adrenergic reaction of the rat small intestine].

Acetylcholine and serotonine depressed the sensitivity of the rat small intestine's receptors and enhanced the maximal alpha-adrenergic response. Acetylcholine acted as a competitive inhibitor of beta-adrenergic response, the latter being insensitive to serotonine. Acetylcholine even in the threshold concentrations (1.0 x 10(11) M) increased the noradrenaline desensitization of the adrenoreceptors.

Acetylcholine↗

PubMed1986

[Desensitization of alpha-adrenoreceptors of the small intestine of the rat].

A study performed on the isolated section of the rat small intestine has shown that at a slow increase in the concentration of the specific alpha-adrenomimetic phenylephrine in the incubation medium 1.0 X 10(-8) M/sec) adrenoreceptors pass into a state of desensitization without excitation, and no reaction takes place. At 2.5 X 10(-8)-10 X 10(-8) M/sec the reaction develops depending on the rate of phenylephrine introduction and is stabilized at 5.5-5.8 X 10(-6) M. Apparently, under these conditions an equilibrium is set up between activation and desensitization of adrenoreceptors. The role of desensitization of alpha-adrenoreceptors in the regulation of adrenergic reaction is discussed.

Animals↗

PubMed1986

[Relation between adrenoreceptor desensitization and their specific sensitivity].

In isolated parts of the rat small intestine, the relationship between desensitization of alpha- and beta-adrenoreceptors and change of their specific sensitivity was studied upon a decrease in noradrenaline content and increase of the incubation medium temperature. An enhancement of the adrenomimetics affinity was always followed by an increase in their ability for desensitization, thus entailing an increased effect of adrenomimetics as the autoinhibitors of adrenergic responses. The dependence of the adrenoreceptors ability for desensitization of their affinity for noradrenaline seems to ensure the control of adrenergic response upon a change in activity of adrenoreceptors.

Animals↗

PubMed1985

[Effect of temperature on the adrenoreactivity of the small intestine in the rat].

In isolated sections of the rat small intestine, adrenergic responses to phenylephrine (P), noradrenaline (NA) and isopropylnoradrenaline (IN) were studied at various temperatures of the incubation medium. Raise of the temperature from 33 to 37 degrees C increased the sensitivity of adrenoreceptors to P and NA 3.2-and 2.1-fold but did not change the sensitivity to IN. This change of adrenoreactivity was eliminated by phentolamine blockade of alpha-adrenoreceptors, and the raise of temperature always produced a decrease in maximal reaction of the small intestine. The change of adrenoreceptors of the small intestine smooth muscles seems to be related primarily to the rearrangement of alpha-adrenoreceptors.

Adrenergic Fibers↗