The experiments in the present work, representing a part of a wider study of the reactivity of smooth muscles of spontaneously hypertensive rats, were carried out on anococcygeal muscles of Wistar male and female normotensive rats (NTR) and on spontaneously hypertensive rats (SHR), divided in two age groups: young -2.5 to 4 months, and adult -6 to 12 months. The effects of noradrenaline (NA), isoprenaline (IPNA) and phentolamine (Ph) were studied in parallel experiments on smooth-muscle preparations of NTR and SHR. NA (1 x 10(-10)-1 x 10(-4) M) and IPNA (1 x 10(-4)) caused stronger contractions in NTR preparations. The affinity of alpha-adrenoreceptors to NA was increased in the SHR preparations. Ph (1 x 10(-8)-1 x 10(-6) M) inhibited more markedly the NA-contractile effects on smooth muscles of young male SHR. The inhibitory action of Ph On IPNA-induced contractions was less manifested on SHR anococcygeal muscles. It is seen from the results obtained that the adrenergic reactivity of SHR anococcygeal muscle is reduced, which is in agreement with the data in the literature and with our earlier assumption concerning the mosaic character of the specific features of the adrenergic transmission in SHR. The established increased affinity to the transmitter of the alpha-adrenergic receptors in SHR probably represents a peculiar compensatory mechanism for facilitating the adrenergic neurotransmission with reduced capacity of the smooth-muscle effector system to transform the stimulus generated during contraction.

Age Factors↗

PubMed1982

Interaction of histamine with adrenergic smooth muscle neurotransmission. I. Effects of histamine on smooth muscle contractions induced by exogenous or by endogenous noradrenaline.

The effects of histamine on contractions in response to exogenous noradrenaline or to electrical stimulation were studied on two smooth muscle preparations with adrenergic neurotransmission--rat anococcygeal muscle and vas deferens. Histamine (1 X 10(-6)M-1 X 10(-4)M) did not affect significantly the contractions of vas deferens induced by noradrenaline (1 X 10(-8)M-1 X 10(-4)M), but decreased in a concentration-dependent manner the contractile effects of noradrenaline on anococcygeal muscle. The EC50 of noradrenaline on the latter preparation was increased 2.6-16.2 times by histamine but the antagonism was of a noncompetitive type. Histamine exerted a biphasic effect on the smooth muscle contractions in response to square wave electrical stimulation with supramaximal voltage (vas deferens--0.1 Hz, 1 sh or 10 Hz, 20 sh; anococcygeal muscle--5 Hz, 8 sh or 10 Hz 20 sh). The lower histamine concentrations (1 X 10(-12)M-1 X 10(-7)M) slightly potentiated the contractions and the higher concentrations (1 X 10(-6)M-1 X 10(-4)M) markedly inhibited the contractions in response to electrical stimulation. The results obtained are consistent with the hypothesis that the modulatory role of histamine for the adrenergic neurotransmission is mediated via presynaptic inhibitory H2--and postsynaptic excitatory H1--histaminergic receptors.

Animals↗

PubMed1982

Interaction of histamine with adrenergic smooth-muscle neurotransmission. II. Significance of calcium ions for the effects of histamine on contractions induced by endogenous noradrenaline.

The role of Ca2+ for the effects of histamine on contractions induced by electrostimulation has been studied on smooth-muscle organs with adrenergic neurotransmission (rat anococcygeal muscle and vas deferens). The low Ca2+-concentrations in the organ bath (below 1.8 mM) reduce the amplitude of the smooth-muscle contractions in response to electrostimulation (more markedly at the low frequency), at the same time potentiating the inhibitory action of histamine on the electrostimulation-induced contractions of the isolated preparations. Raising the Ca2+-concentration in the nutrient medium increases the magnitude of the contractions in response to electrostimulation. At the same time the high Ca2+-concentrations weaken the second (inhibitory) phase of the action of histamine on the electrostimulation-induced contractions of the smooth-muscle preparations. The potentiating action of histamine on contractions in response to electrostimulation is not essentially influenced by the changes in Ca2+-concentration. The data obtained show that Ca-ions may play a role in the mechanism of the inhibitory action of histamine on the smooth-muscle adrenergic neurotransmission, which is assumed to be mediated by presynaptic H2-histaminergic receptors.

Animals↗

PubMed1982

Interaction of histamine with adrenergic smooth-muscle neurotransmission. III. Significance of magnesium ions for the effects of histamine on contractions induced by endogenous noradrenaline.

The significance of Mg2+ for the effects of histamine on smooth-muscle contractions in response to electrostimulation with different frequency has been studied in organs with adrenergic neurotransmission (prostatic part of vas deferens and anococcygeal muscle of rats). Reduction of the concentration of Mg-ions below 1.05 mM usually markedly potentiates the electrostimulation-induced contractions, whereas high Mg2+-concentrations (above 1.05 mM) sharply reduce their magnitude. The changes in the concentration of the Mg-ions in the nutrient medium do not influence essentially the inhibitory effects of histamine on smooth-muscle contractions in response to electrostimulation. In the presence of lower concentrations muscle contractions in response to electrostimulation. In the presence of lower concentrations of Mg-ions, the potentiating effect of histamine on electrostimulation does not change substantially. The rise in Mg2+-concentration above 1.05 mM considerably increases the potentiating action of the low histamine concentrations on the electrostimulation-induced contractions. This effect was more pronounced in smooth-muscle preparations stimulated with a lower frequency. The data obtained suggest that histamine counteracts the contractile response to electrostimulation induced by high concentrations of Mg-ions. It may be assumed that Ca-ions also participate in the realization of this histamine effect.

Animals↗

PubMed1982

[Embryotoxic and teratogenic effect of Pharmachem tetramisole].

Studies were carried out to establish the effect of high rates of Tetramizol Pharmachim on the embryonal and fetal development in rats. The preparation was administered orally to pregnant animals under the form of a 1 per cent solution at the rate of 1/5 LD50 (=200 mg/kg), on the fourth and the thirteenth day of gestation. It was found that the amount of the preparation applied on the fourth day after conception took place led to rise of the preimplantation loss of embryos. The rate of the total embryonal mortality also rose. Accordingly, it was concluded that in high doses Tetramizol Pharmachim could produce an embryotoxic effect on rats. The application of the preparation later during pregnacy (the 13th day) did not have an adverse effect on the normal course of gestation. No abnormal effects were demonstrated on the growth and development of fetuses during all stages of investigation, which might point to the teratogenic action of Tetramizol.

Animals↗

PubMed1981

Effect of histamine on smooth-muscle contractions induced by noradrenaline and acetylcholine.

The effects of different histamine concentrations (1 X 10(-6) to 1 X 10(-4)M) on the contractile effects of noradrenaline and acetylcholine are studied on isolated smooth-muscle preparations from rats. Histamine, applied in concentrations of 1 X 10(-5)M and 1 X 10(-4)M, markedly potentiates the contractile effects of the lower concentrations of acetylcholine on the anococcygeal muscle, without essentially changing the maximum contractions induced by it. Histamine reduces 6.5-31.6 times the acetylcholine concentrations causing 50 per cent of the maximal contractions of this smooth-muscle preparation. Application of histamine on anococcygeal muscle decreases contractile responses to noradrenaline. A dependence is found between the histamine concentration used and the shift to the right of the curve "log concentration-effect" for noradrenaline. Histamine increases 2.6 to 16.2 times the noradrenaline concentrations needed for inducing 50 per cent of the maximum contractile response of the anococcygeal muscle. The interaction between noradrenaline and histamine on this smooth-muscle preparation is not competitive. Histamine in the concentrations applied does not influence the contractile effects of noradrenaline on vas deferens and of acetylcholine on tracheal smooth-muscle preparation. In rat anococcygeal muscle histamine most probably influences the contractile effects of noradrenaline and acetylcholine through allosteric interaction with their receptors.

Acetylcholine↗

PubMed1981

On the mechanism of guinea-pig tracheal relaxation induced by high histamine concentrations.

In concentrations higher than 1 X 10(-3)M histamine relaxed guinea-pig tracheal strips previously contracted by lower histamine concentrations. The blocker of H1-histaminergic receptors diphenhydramine (1 X 10(-6)M and 1 X 10(-5)M) and the alpha-adrenoblocker phentolamine (1 X 10(-5)M) potentiated histamine-induced relaxation. The beta-blocker propranolol (1 X 10(-4)M) decreased the histamine relaxant effect. Oxprenolol (1 X 10(-4)M) that is a less potent blocker of the tracheal beta 2-adrenoreceptors and is a partial beta-agonist did not influence histamine-induced relaxation. It is suggested that high histamine concentrations relax the guinea-pig tracheal strips by activating the H2-receptors and by depleting catecholamines in the smooth muscle.

Animals↗

PubMed1981

The effect of new local anaesthetics on tracheal and anococcygeal smooth muscle.

The effects of pentacaine and heptacaine were compared with that of procaine on the isolated tracheal smooth muscle of guinea-pigs and anococcygeal muscle of rats. Pentacaine increased the initial tone of the tracheal smooth muscle. In higher concentration however pentacaine and heptacaine induced smooth muscle relaxation. Pentacaine diminished the action of histamine on the tracheal smooth muscle and both pentacaine and heptacaine depressed the effects of noradrenaline and acetylcholine on anococcygeal muscle.

Anal Canal↗

PubMed1981

[Dehiscence of episiotomies at the gynecologic-obstetrical clinic from 1975 to 1980].

Explore the source record for details and available documents.

Episiotomy↗

PubMed1980

[Transplantation method for fertilized ova at the blastocyst stage studied in experimental animals].

Explore the source record for details and available documents.

Animals↗

PubMed1980

On the interaction of histamine with the tryptaminergic smooth-muscle receptors.

The effect of histamine (1 x 10(-8) to 1 x 10(-3) M) on the contractile effects of 5-hydroxytryptamine (1 x 10(-10) to 1 x 10(-3) M) has been studied in experiments on isolated smooth-muscle preparations (rabbit duodenum and guinea-pig trachea). Applied in lower concentrations in both smooth-muscle preparations, histamine does not influence essentially or slightly lowers the contractions induced by the low concentrations of 5-hydroxytryptamine (5-HT). At the same time the contractile effects of the high 5-HT concentrations are reduced by about 15-30 per cent. Increasing the histamine concentration in the organ bath reveals a potentiation of the contractile responses caused by the low 5-HT concentrations by about 10-25 per cent. The contractile effects of the high 5-HT concentrations are reduced by 10-30 per cent on the background of the high histamine concentrations in advance. The results obtained show that histamine influences the 5-HT-induced contractions most probably through allosteric interaction with the tryptaminergic receptors in the smooth-muscle organs studied.

Animals↗

PubMed1979

[Effect of halothane (narcothane) on intrauterine fetal development].

The authors examined the effect of chalotane (narcotann ne-Spofa) on the development of a rat fetus. The rats were divided into groups and were narcotised for a period of 4 hours as well as 4.5 days. One of the group was narcotised from the 8 to the 13 day of gestation. Narcosis was made in chambers with dynamic inhalatory regimen at concentration of narcotane of 10 mg/m3 and 250 mg/m3. There was blastopathogenic effect of narcotane, manifested by an early resorption of nidaded ova, by nonspecific action on the fetus, which inhibited growth and development of the fetus and raised the mortality of the fetuses. The amount of estriol was diminished in mothers, treated with 250 mg/m3 of the drug.

Alkaline Phosphatase↗

PubMed1979

[Effect of bee venom and its low- and high-molecular fractions on embryogenesis in rats].

The authors injected 3 groups of pregnant rats with 1/5 of LD50 of whole bee venom and its low and high weight molecular fractions daily between the 6th and 14th day of gestation. The embryos of the treated animals, aged 20 days, showed a reduction of the weight and dimunution of the activity of lactate dehydrogenase and isocitrate dehydrogenase in their liver homogenate. There were autolisis and dead rats in the uterus of the treated animals (embryotoxic effect). There were no teratogenic alterations. The low weight molecular fraction of the bee venom revealed more manifested embryotoxic effect.

Animals↗

PubMed1979

Pharmacological studies of a group of semi-synthetic structural analogues of glaucine.

Glaucine and the newly-synthesized compounds possess some general properties conditioned by the common apomorphine structure - inhibition of the central nervous system, brief decrease in blood pressure and spasmolytic action. At the same time the changes in the structure of glaucine lead to quantitative or qualitative changes in some of its effects. Substitution of hydrogen in 3rd position with -CH2. NH-group reduces glaucine toxicity 3.5 times. Still greater decrease in the toxicity (7.5-10 times) is found in the case of N-oxidation or dehydrogenation of glaucine. The extension of the methyl group in 3rd position with a hydroxy group or with an amide residue of the benzoic acid, as well as the dehydrogenation and N-oxidation of glaucine, lead to intensification of the inhibitory action on the central nervous system. With the exception of 7-methyl dehydroglaucine which has antitussive action similar to glaucine, the other glaucine structural analogues do not possess this property. Both glaucine and its structural analogues exercise a bronchoconstrictor effect. 3-Aminomethyl derivatives preserve the spasmolytic activity of glaucine, and their several-fold lower toxicity makes them more promising spasmolytic agents than glaucine. Dehydrogenation and N-oxidation of glaucine reduce considerably its spasmolytic action.

Alkaloids↗