Possible mechanisms for the inhibitory effect of Ruscus extract on increased microvascular permeability induced by histamine in hamster cheek pouch.

Extract of Ruscus aculeatus is used in treatment of venous insufficiency. In the present study, we used the hamster cheek pouch preparation and investigated in vivo the effects of an alpha 1 and alpha 2 adrenoceptor antagonists, a calcium blocker, Ruscus extract, and their combination on increased microvascular permeability induced by histamine. Experiments were performed on male hamsters; 30 min after completion of the cheek pouch preparation, fluorescein-labeled dextran (molecular weight 150,000) was given intravenously (i.v.). Histamine, applied topically, increased the number of fluorescent vascular leakage sites from postcapillary venules, evidence of an increase in macromolecular permeability, which was quantified by ultraviolet light microscopy as the number of leaky sites in the prepared area. Prazosin (alpha 1-adrenoceptor antagonist), diltiazem (calcium blocker), and Ruscus extract applied topically dose-dependently inhibited the macromolecular permeability-increasing effect of histamine. Rauwolscine (alpha 2-adrenoceptor antagonist), also applied topically, had no effect on histamine-induced permeability increase. Inhibition of the histamine-induced permeability increase evoked by Ruscus extract could be blocked by prazosin and by diltiazem but not by rauwolscine. These results indicate that any variation in the transmembrane flux of calcium impairs formation of microvascular leaky sites by histamine. Our results show that Ruscus extract has a protective effect against the leakage of FITC-dextran in hamster cheek pouch after administration of histamine that is modulated by calcium and selectively by alpha 1-adrenoceptors.

Possible mechanisms for the venular constriction elicited by Ruscus extract on hamster cheek pouch.

We investigated the influence of alpha-adrenoceptors blockers and calcium blockers on the effects of the venotonic agent Ruscus extract on the diameter of arterioles (ID 10-70 microns) and venules (ID 20-135 microns) of hamster cheek pouch microvasculature in vivo. For microcirculatory measurements, the preparations were placed under an intravital microscope coupled to a closed-circuit TV system. The TV monitor display was used to obtain arteriolar and venular internal diameter recordings (always at the same site) by an image shearing device. All drugs were applied topically. Ruscus extract was tested in different concentrations and in combination with prazosin (alpha 1-adrenoceptor antagonist), rauwolscine (alpha 2-adrenoceptor antagonist), or diltiazem (calcium blocker). Topical application of Ruscus extract elicited concentration-dependent responses in the studied vessels: arterioles remained unchanged in the concentration range tested, whereas venules remained unchanged or constricted depending on the concentration used. The observed venular constriction could be blocked by low concentrations (10(-9) M) of prazosin or diltiazem and by high concentrations (> 10(-6) M) of rauwolscine. Our results suggest that the venular constriction elicited by Ruscus extract in vivo, at the microcirculatory level, is mediated by calcium and by alpha-adrenoceptors and further support data previously reported on larger vessels and on patients with venous insufficiency.

Platelet inhibitory functions of aortic endothelial cells. Effects of eicosapentaenoic and docosahexaenoic acids.

The endothelial cell platelet inhibitory potential was assessed directly by measuring the platelet inhibition induced by platelet interaction with the cultured aortic endothelial cell. The prostacyclin content of the platelet suspensions after interaction was also quantified. We found that prostacyclin production accounted for the overall platelet inhibitory potential of the aortic cells since: (a) endothelial cells incubated with aspirin, which did not produce prostacyclin, did not inhibit platelets; (b) the prostacyclin content of platelet suspensions after interaction with endothelial cells correlated with the extent of the platelet inhibition; (c) such a platelet inhibition was reproduced by adding synthetic prostacyclin in amount equivalent to that produced by endothelial cells during the interaction. Eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids incorporated into endothelial phospholipids, decreased the ability of the cells to produce prostacyclin and to inhibit platelets, DHA being less effective than EPA.

Effects of Ruscus extract on the internal diameter of arterioles and venules of the hamster cheek pouch microcirculation.

In the present study, we investigated (a) the effects of the extract of Ruscus aculeatus, which is used to increase peripheral venous tone, on the diameter of arterioles (ID range 10-70 microns) and venules (ID range 20-135 microns) of hamster cheek pouch microvasculature in vivo and (b) the influence of temperature on the observed effects. For microcirculatory measurements, the preparations were placed under an intravital microscope and coupled to a closed-circuit TV (ccTV) system. The TV monitor display was used to obtain arteriolar and venular ID recordings (always at the same site) by an image shearing device. For systemic intravenous (i.v.) administration, the measurements were performed every 10 min, before (control) and after injection of the extract (5 mg/kg). During topical application, the extract was tested, in different concentrations, at 25 degrees, 36.5 degrees, and 40 degrees C. Systemic i.v. administration of Ruscus extract evoked venular constriction and did not affect the arteriolar diameter or mean arterial pressure (MAP). Topical application of Ruscus extract elicited concentration- and temperature-dependent responses in the vessels. At 25 degrees C, arterioles and venules dilated; at 36.5 degrees C, the arterioles remained unchanged while the venules constricted, and at 40 degrees C, the arterioles remained unchanged or constricted depending on the concentration used while the venules further constricted. The effects of Ruscus extract observed in vivo at the microcirculatory level further support the data previously reported on larger vessels and on patients with venous insufficiency.

Inhibitory effect of the Ruscus extract and of the flavonoid hesperidine methylchalcone on increased microvascular permeability induced by various agents in the hamster cheek pouch.

The Ruscus extract and the flavonoid hesperidine methylchalcone (HMC) are used in treatment of venous insufficiency. In the present study, we used the hamster cheek pouch preparation and investigated the effects of these substances on increased microvascular permeability induced by bradykinin, histamine, and leukotriene B4 (LTB4) applied topically. Experiments were performed on male hamsters; 30 min after completion of the cheek pouch preparation, fluorescein-labeled dextran [molecular weight (mol wt) 150,000] was given intravenously (i.v.). Bradykinin, histamine, and LTB4 increased the number of fluorescent vascular leakage sites from postcapillary venules, evidence for an increase in macromolecular permeability, which was quantified in ultraviolet (UV)-light microscope as the number of leaky sites in the prepared area. Ruscus extract and HMC, given i.v., significantly inhibited the macromolecular permeability-increasing effect of bradykinin, LTB4, and histamine. Ruscus extract, applied topically, dose dependently inhibited the macromolecular permeability-increasing effect of histamine. Our results show that Ruscus extract and HMC have a protective effect against leakage of FITC-dextran in the cheek pouch after administration of various permeability-increasing substances, which further supports data previously reported on patients with venous insufficiency.

[Comparative biochemical and ultrastructural study of the hepatic response induced in the rat by 2 hypolipemic agents: clofibrate and itanoxone]. / Etude comparative biochimique et ultrastructurale de la réponse hépatique induite chez le rat par deux agents hypolipémiants: clofibrate et itanoxone.

A comparative biochemical and ultrastructural investigation o hepatic response induced in rats by clofibrate and itanoxone, a new hypolipemic agent, was performed. Normocholesterolemic Sprague-Dawley male rats were distributed into homogeneous groups and orally treated on 10 successive days either by the vehicle alone (1%--carboxymethylcellulose), or by clofibrate (300 mg/kg/day) or by itanoxone (100 and 300 mg/kg/day). On the eleventh day, a last dose was applied after about 16 hours fasting, one hour before sacrificing the animals. Biochemical parameters (total serum cholesterol, hepatic catalase activity) and morphological ones (liver weight, ultrastructural analysis of the hepatic cell with especially cytochemical evaluation and counting of peroxisomes) were studied. The treatment with clofibrate gave the following results: fall in total serum cholesterol (-25%), increase in liver weight (+89%) and hepatic catalase activity (+69%), high proliferation of hepatic peroxisomes (+246%). These data are in agreement with literature. The following observations were noted with itanoxone: a decrease in total serum cholesterol proportional to the dose applied and of higher intensity as compared to clofibrate (-36,5% at 100 mg/kg; -54% at 300 mg/kg), a moderate increase in liver weight (+25% at 100 mg/kg; +41% at 300 mg/kg) and hepatic peroxisomes (+12% at 100 mg/kg; +85% at 300 mg/kg), no effect on hepatic catalase activity. The moderate feature of the hepatic response induced by itanoxone in spite of a marked hypocholesterolemic activity was discussed: first in connection with the hypothesis about a relation between the proliferation of hepatic peroxisomes induced by many hypolipemic agents and the advent of tumors in rats, then, in connection with the association sometimes assumed between the increased number of hepatic peroxisomes and the effect on lipids of several hypolipemic substances related or not to clofibrate.

Effect of temperature on the responsiveness of cutaneous veins to the extract of Ruscus aculeatus.

In canine cutaneous veins cooling augments and warming depresses the responses to sympathetic nerve stimulation. In these veins the extract of Ruscus aculeatus (Ruscus) causes contractions due to alpha-adrenergic activation. To determine the effects of temperature on the response to Ruscus, rings of canine saphenous veins were studied at 24 degrees, 37 degrees and 41 degrees C. At 37 degrees C, Ruscus caused an increase in isometric tension which was depressed by prazosin and rauwolscine. Cooling inhibited the response to Ruscus, while warming augmented it. Rauwolscine potentiated, and prazosin reversed the effect of cooling on contractions evoked by Ruscus. Prazosin reduced, and rauwolscine augmented the effect of warming. These experiments demonstrate that temperature affects the venoconstriction induced by Ruscus in an opposite fashion as that to sympathetic nerve activation, presumably because the alpha 1-adrenergic component of the response to Ruscus predominates.

[An experimental model of osteoarthritis. II.- Biochemical study of collagen and proteoglycans]. / Etude d'un modèle expérimental d'arthrose. II.-Etude biochimique du collagène et des protéoglycanes.

We investigated biochemical modifications of the initial phase of cartilage degradation in an osteoarthritic model developed in the rabbit by intraarticular papain injection. The amino-acid composition of the collagen did not differ significantly between control and papain-treated groups. After 3H-proline in vivo incorporation, the absence of radioactivity in peaks beta 12 and alpha 2 shows that cartilage did not synthesize type I collagen in noticeable quantity during the labelling period. The study of proteoglycans by the use of the "fixed charges density" (FCD) shows that in our model they decreased rapidly and substantially, as in human disease. The decrease was measurable from 1 h after injection with a minimum at about 24 h (54% of the normal level). However, increased 35SO4 incorporation was observed, beginning very soon after injection and passing through a maximum (500% of the normal level) around the 3rd day. The rates of 3H-proline incorporation and 3H-hydroxyproline formation were decreased in the treated cartilage in a similar way as for the proteoglycans, with a minimum (55% of the normal level) at about 24 h. The "turn-over" of 3H-hydroxyproline and "non collagen" 3H-proline were increased in the treated cartilage. The half-lives of both amino-acids went respectively from 26 to 15 days and from 14 to 10 days. Injection of papain in the rabbit knee-joint produced a major loss of ground substance and a reaction of the chondrocytes. The cells metabolism seemed modified with especially a catabolism stimulation.

[An experimental model of osteoarthritis. I. Induction and ultrastructural study]. / Etude d'un modèle expérimental d'arthrose. I.--Induction et étude ultrastructurale.

Starting from Bentley's works [2], we elaborated an experimental model of arthrosis easy to use, providing reproducibility of effects and showing the same development as the human disease, but within a far shorter time. Papain injection induced a quick, high loss in proteoglycans. A rapid, localised chondrocyte reaction in the middle layer of the support area was noted. In this area, cells rapidly showed hyperactivity signs and a crown of microfibers taking the amyloid tissue-specific staining was seen around them. The building of such crowns might result from a discrepancy between collagen and proteoglycan secretion inducing a modification in their inter-relations. We also noticed binucleate cells, someones being in process of division, which might be the beginning of clones.

Activity of anti-inflammatory drugs on an experimental model of osteoarthritis.

Osteoarthritis was induced in the rabbit by a single intra-articular injection of 0.1 ml of a 1% solution of papain. Degeneration of the cartilage was studied 3 hours, 1, 3 and 8 days after the injection by transmission electron microscopy (TEM) and quantified by measuring the fixed charge density (FCD) and 35S incorporation into glycosaminoglycans. TEM observations of chondrocytes revealed a close correlation between the development of this experimental degenerative joint disease and human osteoarthritis. The administration of CH3-prednisolone (0.1 mg/kg on the 2nd and 5th days, i.a.), of indomethacin (1 mg/kg per day X 7, i.v.), and of catalase (50,000 IU/kg per day X 7, i.m.) modified the biochemical parameters measured 8 days after the papain injection. The corticoid potentiated the action of papain (fall in GAG content and synthesis). None of the non-steroid anti-inflammatory drugs modified the FCD. On the other hand, the increase of 35S incorporation was low after indomethacin and very high after acetylsalicylic acid. Catalase brought about an almost complete recovery of GAG content, together with an important increase in 35S incorporation. This arthropathy could be widely used in experimental pharmacology as a selective test and as a means of studying the mechanism of action of osteoarthritic drugs.