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M Nechifor

Publications and source records attributed to M Nechifor.

At least 19 recordsLinked to original sources
PubMed2006

Effects of novel leukotriene receptor antagonists in the isolated rat aorta.

We screened 14 novel antagonists of the LTB(4) and LTD(4) receptors (also inhibitors of LTB(4) synthesis) for their vasoactive properties in the isolated rat aorta. The compounds belong to three classes, e.g. quinoline (Q), phenetylamido (P), and resatophenone (R) derivatives. They are effectiveless in resting conditions and generally display a weak relaxing ability against contraction by either high K(+) or alpha(1) adrenoceptor activation, either in the presence or absence of a functional endothelium. There is little overlap with the generally lower concentration range where their anti-LT properties are already manifested. We could not find any correlation between any of the anti-LT properties and the vasorelaxant effects. Concerning the non-specific vasoactive properties, choice compounds of the examined groups could be further tested regarding the mechanisms of their relaxing effects. Given the many uncertainties concerning LT and vascular physiology, it may be worthy to proceed with this line of investigation.

Acetophenones↗
PubMed1995

Effects of liposome-entrapped platelet-activating factor in the isolated rat trachea.

The effects of platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine)-filled liposomes upon rat tracheal rings in vitro were examined. The capture of liposomes by the smooth muscle cells of the isolated tracheal rings as well as the release of their content into the cytoplasm was shown by using Evans blue (5 x 10(-4) M)-loaded liposomes. Administration of PAF (10(-3) M)-filled liposomes contracted the preparations, in contrast with extracellular administration of PAF and control liposomes, which had no effect. Administration during the plateau or pretreatment with liposomes containing BN 52021 (3-t-butylhexahydro-4,7b-trihydroxy-8-methyl-9H-1,7a-epoxymethano- 1H,6aH- cyclopenta[c]furo(2,3-b)furo[3',2':3,4]cyclopental [1,2-d]furan-5,9,12(4H)-trione) ((10(-3) M, a selective PAF receptor antagonist) or heparin (5 x 10(-5) M) blocked this contraction. BN 52021 and heparin, not entrapped in liposomes, had no such effect. Our data suggest an intervention of PAF in the mechanisms of contraction of tracheal smooth muscle, involving a direct or indirect intervention (intracellular receptors for PAF cannot be excluded). At the same time, the rat trachea contraction induced by PAF-loaded liposomes could be linked to the PtdIns(1,4,5)P3-dependent Ca2+ channels from the endoplasmic reticulum and/or to the interaction with G proteins, as shown by the blocking effects of heparin-containing liposomes.

Animals↗
PubMed1992

Influence of cloprostenol in the experimentally induced ulcer in rats.

We have tested the action of cloprostenol a relatively stable analogue of PGF2 alpha in experimentally induced gastric ulcer in rats by contention stress or indomethacin. Our results show that CIPG, administered at higher doses than those inducing an luteolytic effect, has a gastroprotective effect both in the contention stress-induced ulcer (2.30 + 0.26 in series III as compared to 3.80 +/- 0.73 in series III, p < 0.01) and in indomethacin-induced ulcer (2.69 +/- 0.38 in series V as compared to 3.61 +/- 0.34 in series IV, p < 0.01).

Animals↗
PubMedDate not supplied

[Experimental ethanol poisoning in rats].

Ethanol is one of the most used substances that produce liver lesions. The differences between species, the pathway of administration and the genetic variation are factors that influence the response of liver to ethanol. The experiment used adult male Wistar rats and the hepatic lesions were assessed using standard histological examination. The results show an increase of triglycerides in liver cells even in acute intoxication, the most affected cells being located in the periphery of the hepatic lobule, associated with a dilatation of blood vessels.

Animals↗
PubMedDate not supplied

The influence of some prostaglandin analogous on the female rat ovary and uterine tube epithelium.

The synthetic analogous of the prostaglandins are utilized in the obstetrical and gynecological therapy for multiple purposes. 4 lots with 12 nonpregnant female rats were use: the Ist received 25 g/kg/day isopropyl ester PGF2; the IInd lot received 50 g/kg/day isopropyl ester PGF2; the IIIrd lot received 50 g/kg/day optic active cloprostenol; the IVth lot was the witness lot. The medication was intraperitoneally (i.p.) administrated in a unique daily dose. Prostaglandin F2 analogous at small doses (25 micrograms/kg/day) induce vasodilating effects on the ovary blood vessels and functional luteolysis rather than structural luteolysis. Both of the prostaglandins analogous at doses of 50 micrograms/kg/day present obvious vasodilating and luteolytic effects, although the intensity of the phenomenon is not the same, cloprostenol is more active, inducing a more obvious vasodilatation and luteolysis.

Animals↗
PubMedDate not supplied

[The luteolytic action of prostaglandin F2-alpha analogues in guinea pig's ovary].

The role of prostaglandin at the level of the female genital system is multiple; they are involved in ovulation, luteolysis, contractility of the tube muscles, contraction of the gravid uterus, dilatation of the cervix. The synthetic analogous of the prostaglandin F2 alpha are utilized in a large area of treatments, for multiple purposes. The study was made on 2 lots with 10 non pregnant female guinea pig: the first lot was the witness lot and didn't receive any substance. The second lot received 100 micrograms/kg/day Isopropyl ester PGF2 alpha. The prostaglandin analogous produces vasodilating effects on the ovary blood vessels and luteolytic effects with the destruction of the ovarian follicles.

Animals↗
PubMedDate not supplied

[The influence of some synthetic prostaglandin F2alpha analogous on rat lung].

The role of prostaglandins and their synthetic analogous at the level of the female genital system is multiple. The synthetic analogous of the prostaglandin F2 alpha are utilised in a large area of treatments, for multiple purposes, but their influence on the lung is not so well known. The study was made on 2 lots with 12 non pregnant female rats: the first lot was the witness lot and didn't receive any substance. The second lot received 25 micrograms/kg/day Flavoliz (synthetic analogous of the prostaglandin F2 alpha). The prostaglandinic analogous produces vasodilating effects on the lung blood vessels and moderate pulmonary destruction.

Animals↗
PubMedDate not supplied

Implications of imidazolines and imidazoline receptors role at the vascular level.

There are both post- and pre-synaptic vascular imidazoline (IM) binding sites. The importance of direct IM actions and that of peripheral imidazoline receptors (IRs) are shadowed by the central effects of IMs and by their interaction with alpha 2 adrenoceptors. Since the discovery of clonidine the many studies on IMs have been focused on their hypotensive effect, with rilmenidine and moxonidine as representative drugs. Formerly called IM preferring alpha 2 or IM/guanidium sites, the IRs (idazoxan-sensitive) are the plasmalemmal I1 (clonidine-sensitive) and the various I2 (one structure identified as MAO). I1 signaling includes activation of phosphatidylcholine-selective phospholipase C and inhibition of some ligand-gated channels. Inhibitory IRs on postganglionic sympathetic terminals, are not alpha 2, H3, I1 or I2. Some IMs directly affect CaL, while others inhibit K+ efflux. Clonidine-displacing substances including agmatine are endogenous ligands at IRs and alpha 2 and may participate in arterial pressure control. Beside few speculations, the roles of vascular IRs are largely unknown.

Antihypertensive Agents↗
PubMedDate not supplied

The apoptosis of the rat and mouse testicular cells could be induced by synthetic analogous of the prostaglandin F2 alpha?

Numerous actions of the synthetic analogous of the prostaglandins were used in human and veterinary therapy. The action of these analogous (even, initially the prostaglandins were put in evidence in the seminal plasma) on the male reproductive system are little known. This is the reason for our study, which tried to emphasize the effects of analogous of the prostaglandin F2 alpha on the apoptosis of the rat and mouse testicular cells. Optic active Cloprostenol and Cloprostenol Isopropyl ester, in a dose of 100 micrograms/kg/day induces significant histopathologic modifications in the testis of rats and mice. These changes are evident after 14 days of treatment, but especially after 28 days of treatment.

Animals↗
PubMedDate not supplied

[Imidazoline receptors-normal and pathological factors].

Imidazolinic receptors I1 and I2A and I2B different from alpha 2 receptors and by any other type of receptors were identified in the last years in many tissues from human body and in cells of a great number of animals. There are agonists and antagonists on I1 receptors (e.g., agonists like moxonidine, rilmenidine and antagonists like efaroxan, BAF 6143 etc.) and also on I2 receptors (e.g., agonist-idazoxan, etc.). There are many actions performed by stimulation of imidazolinic receptors like: decreasing of blood pressure (I1 stimulation from midbrain), decreasing of noradrenaline plasmatic level, antiarrhythmic actions in experimental arrhythmias etc. Imidazolinic receptors are involved in natriuresis, pancreatic insulin production, some superior nervous activities, regulation of food intake etc. We consider that imidazolinic receptors and their endogenous agonists (e.g. agmatine) represent an important system involved in modulation of cell function.

Adrenergic Agonists↗
PubMedDate not supplied

Role of the epithelial derived factors on airway reactivity.

A tracheobronchial smooth muscle reactivity study on isolated guinea pig tracheal rings was done. The existence of two different factors active on the smooth muscle, an inhibiting one as well as an activating one were identified. Generated on different pathways, the epithelial derived relaxing factor is a cyclooxygenase dependent prostaglandin, while the activating epithelial factor seems to be a thromboxane derivative.

Airway Resistance↗