Edematogenic Activity of Scorpion Venoms from the Buthidae Family and the Role of Platelet-Activating Factor and Nitric Oxide in Paw Edema Induced by <Emphasis Type="Italic">Tityus</Emphasis> Venoms

We compared the edematogenic activity of venoms of scorpions from the Buthidae family, Tityus bahiensis (Tbv), Tityus serrulatus (Tsv) and Rhopalurus rochai (Rrv). Three doses (20, 40 and 80 μg/kg sc) of each venom were administrated in hind paw of mice and edema was measured from 5 min to 24 h. Tbv and Tsv both induced edema of rapid onset (135% of increase at 15 min); Rrv induced only a mild edema (40% of increase). We then investigated the involvement of platelet-activating factor (PAF) and endogenous nitric oxide (NO) in Tbv and Tsv-induced paw edema. Pretreatment of mice with a PAF antagonist (WEB-2170) inhibited Tsv but not Tbv-induced edema. Pretreatment with a non selective inhibitor of NO-synthases (l-NAME) inhibited or increased the edema depending on the dose and the time the edema was measured. In conclusion, the venoms from Tityus are stronger inducers of edema than the venom from the Rhopalurus scorpion. The venoms of Tityus species are similar in potency and time-course edema development. PAF is involved in the edema induced only by Tsv.     

Anti-allergic effects of natural tetranortriterpenoids isolated from Carapa guianensis Aublet on allergen-induced vascular permeability and hyperalgesia

Objective: We investigated the anti-allergic and analgesic properties of an oil and a derived fraction of tetranortriterpenoids (TNTP) obtained from the seeds of Carapa guianensis Aublet.Materials and methods: Pleurisy, paw and ear edema were induced in Swiss and C57/Bl10 mice mice, whereas thermal hyperalgesia was assessed in Wistar rats (n = 6−10 per group). Values of p < 0.05 were regarded as significant.Results: C. guianensis oil (100 to 400 mg/kg, p.o.) and TNTP (12.5 to 100 mg/kg, p.o.) inhibited pleural exudation, paw and ear edema induced by ovalbumin (OVA) in sensitized mice. TNTP (12.5 to 100 mg/kg, p.o.) also inhibited paw edema induced by histamine, PAF and bradykinin. TNTP (100 mg/kg, p.o.) inhibited prostaglandin E₂ generation in the pleural cavity in response to antigenic challenge. Moreover, C. guianensis oil (100 to 400 mg/kg) and TNTP (12.5 to 100 mg/kg) decreased OVA- and histamine-induced hyperalgesia.Conclusion: Taken together, these findings demonstrate the anti-edematogenic and analgesic effects of C. guianensis oil, and points out TNTP as the responsible bioactive compounds.Received 24 November 2004; returned for revision 4 January 2005; returned for final revision 4 March 2005; accepted by N. Boughton-Smith 30 March 2005     

Preventive actions of a high dose of glucosamine on adjuvant arthritis in rats

Objective: Glucosamine, a naturally occurring amino monosaccharide has been used to treat or prevent osteoarthritis in humans. In this study, we evaluated the effect of glucosamine on rat adjuvant arthritis, a model of rheumatoid arthritis.Materials and methods: Adjuvant arthritis was induced in male Wistar rats by injection of Freunds complete adjuvant (FCA) into the right hind paw, and 300 mg/kg of glucosamine, an extra-dose compared with a regular dose for osteoarthritis patients (1.5 g/day, approximately 25 mg/kg), was orally administered once a day to the arthritic rats for 22 days.Results: Glucosamine significantly suppressed the increase in arthritis score (p < 0.05) after day 10 of adjuvant injection, and inhibited the swelling of FCA-injected right and -uninjected left hind paws (p < 0.01) after day 18. In addition, histopathological examination of the arthritic joints revealed that glucosamine suppressed synovial hyperplasia, cartilage destruction and inflammatory cell infiltration. Furthermore, glucosamine reduced the production of nitric oxide and prostaglandin E₂ in plasma (p < 0.05).Conclusions: These observations suggest that glucosamine is able to suppress the progression of adjuvant arthritis in rats. Glucosamine may be expected as a novel anti-inflammatory agent for treatment of rheumatoid arthritis.Received 4 July 2004; returned for revision 8 October 2004; accepted by M. Katori 10 November 2004     

Neutralization of the oedematogenic activity of Bothrops Jararaca venom on the mouse paw by an antibothropic fraction isolated from Opossum (Didelphis Marsupialis) serum

The pharmacological modulation of mice paw oedema produced byBothrops jararaca venom (BJV) has been studied. Intraplantar injection of BJV (1–30 g/paw) produced a dose-and time-related oedema, which was maximal 30 min after injection, reduced gradually thereafter and disappeared over 48h. BJV heated at 100°C for 5 or 15 min blocked local hemorrhage and caused partial inhibition of its oedematogenic activity. The BJV oedema was not inhibited by the anti-histamine meclizine, the inhibitor of histamine and serotonin, cyproheptadine, PAF-acether antagonist WEB 2170 or by the anti-leukotrienes C₄/D₄, LY 171883. Dexamethasone, aspirin, indomethacin, and the dual cyclooxygenase and lipoxygenase inhibitor BW 755C inhibited BJV-induced oedema indicating that arachidonic acid metabolism products via the cyclooxygenase pathway participate in its genesis and/or maintenance. The antibothropic fraction (ABF) (25–200 g/paw) isolated fromDidelphis marsupialis serum neutralized the oedema induced by the venom with and without heating, the hemorrhage induced by BJV and partially blocked the oedema induced by bradykinin and by cellulose sulphate. The oedema produced by histamine, serotonin, PAF-acether or leukotriene C₄ was not inhibited.     

Pharmacologic modulation of D-49 phospholipase A2-induced paw edema in the mouse

Paw edema was produced in CD-1 mice by the injection of 0.3 g of snake venom PLA₂ (A.p. piscivorus D-49) into the hind paw. Edema peaked at 10 min, remained elevated until 60 min, and then declined slowly. The PLA₂ inhibitors, luffariellolide and aristolochic acid, reduced the edema but only when coinjected with the PLA₂. The histamine/serotonin antagonists were the most effective drug class against PLA₂-induced paw edema. The PAF antagonists, CV-6202 (iv) and kadsurenone (coinjected) reduced the PLA₂-induced edema, whereas high doses of the corticosteroids, dexamethasone and hydrocortisone, were also effective. NSAIDs only partially inhibited the paw edema. The LO/CO inhibitors yielded varying activities, with only BW755C and NDGA inhibiting the edema. These results suggest that PLA₂ induces paw edema in the mouse via the action of several classes of inflammatory mediators.     

Anti-inflammatory effect of polyamines in serotonin and carrageenan paw edemata—possible mechanism to increase vascular permeability inhibitory protein level which is regulated by glucocorticoids and superoxide radical

Serotonin paw edema of mice and carrageenan paw edema of rats were inhibited by subcutaneously or orally administered certain polyamines. They must be given at least 2 h before serotonin challenge to get inhibitions which were blocked by the concomitant injections of cycloheximide. Thirty percent inhibitory dose (ID₃₀) of polyamines (s.c.) 3 h before serotonin (s.c.) were: spermidine (8 mg/kg), spermine 28 mg/kg) and putrescine (55 mg/kg). Agmatine, cadaverine, ornithine, citrulline, lysine and arginine were not inhibitory even at 200 mg/kg. Three inhibitory polyamines were effective by oral administration but were not inhibitory by local administration into the paws. Intravenous injections of spermidine also required 2 h of lag period for inhibitions. Serotonin edema was inhibited by dexamethasone (1 mg/kg), predonisolone (1 mg/kg) or by superoxide dismutase (SOD, 5 mg/kg) in lag period requiring manner (s.c. and i.v.). High dose of cyclo-oxygenase inhibitors indomethacin and diclofenac sodium, lipo-oxygenase inhibitor BW755C (30 mg/kg s.c., respectively) and phospholipase A₂ inhibitor quinacrine (100 mg/kg s.c.) failed to inhibit serotonin edema, suggesting that arachidonate metabolites are not participating in this model. ID₃₀ of polyamines which were administered (s.c. and oral) to rats 3 h before carrageenan and determined at 3 h by paw weight were: spermidine (28 and 100 mg/kg), spermine (18 and 90 mg/kg) and putrescine (both>200 mg/kg).Adrenalectomized rats responded to polyamines just as normal rats. Local vascular permeability, irritancy and acute toxicity were also tested in mice. Polyamines were proved to be glucocorticoid-type anti-inflammatory drugs. Polyamines may be mediators of glucocorticoids for the synthesis of the postulated vascular permeability inhibitory protein (called as vasoregulin for convenience). Antiinflammatory effect of glucocorticoid is recently explained by its capacity to induce phospholipase A₂ inhibitory protein(s), (macrocortin or lipomodulin). However, this hypothesis has not yet been proved byin vivo experiment and our data suggest that there is induction by glucocorticoid of another kind of protein which does not inhibit phospholipase A₂ activity.     

Effect of H1- and H2-receptor antagonists on the hemodynamic changes induced by the intravenous administration of ketamine in sevoflurane-anesthetized cats

Objective: The anesthetic ketamine has been reported to cause both an increase of the plasma histamine concentration, notably in cats, and a cardiovascular depression. The latter has been described in humans and in other species. However the relevance of the histamine fluctuation for the ketamine-induced hemodynamic changes has not been determined.Subjects and treatment: We studied the contribution of histamine to the hemodynamic effects induced by IV ketamine (7 mg/kg) in 12 sevoflurane anesthetized cats, of which half had been pre-treated with combined H₁- and H₂ -receptor antagonists.Methods: The mean arterial pressure (MAP) and the heart rate (HR) from both untreated (group C) and pre-treated (group AH) cats were recorded before and after the ketamine administration. The plasma histamine concentration was also measured.Results: Plasma histamine fluctuations in the control and the antihistamine-treated group followed a similar pattern (no statistical differences); an initial rise that peaked 2 min after ketamine injection (from 0.63 ± 0.11 ng/ml to 2.22 ± 0.69 ng/ml in the C group, and from 0.71 ± 0.10 ng/ml to 1.09 ± 0.28 ng/ml in the AH group) followed by an immediate decrease in plasma concentrations. As for the hemodynamic variables under analysis, in the control group ketamine administration was followed by an early 30.3 ± 8.1% reduction (p < 0.005) in the MAP with no associated changes in the HR. In the antihistamine pre-treated group, ketamine caused a further decrease of the MAP (41.7 ± 2.3%), and a significant (p < 0.01) 11.6 ± 2.9% reduction of the HR.Conclusion: Ketamine in anesthetized cats triggers histamine release and induces cardiovascular depression. The depression is more pronounced under the blockade of histamine activity through histamine receptor antagonists.Received 22 October 2004; returned for revision 5 January 2005; accepted by A. Falus 14 February 2005     

Electrophysiological investigation of microdissected gastric glands of bullfrog II. Basolateral membrane properties in the presence of histamine

Following the technical approach described in the preceding publication we have investigated if, and how, stimulation of gastric HCl secretion affects the basolateral ion transport properties of oxyntopeptic cells of Rana catesbeiana stomach. To this end microdissected gastric glands were punctured with conventional or H⁺-sensitive glass microelectrodes and the effects of changing bath ion concentrations on the cell membrane potential (V _b) and cell pH (pH_i) were determined. Except for a transient alkalinization, histamine (0.5 mmol/l) did not significantly affect V _b or pH_i. The latter averaged 7.18±0.03 (mean±SEM, n=5) under resting conditions (0.1 mmol/l cimetidine) and 7.21±0.07 (n=5) in the presence of histamine. In addition, neither the initial velocity nor the final steady-state value of the cell alkalinization following a 101 reduction of bath Cl^– concentration changed in the presence of histamine, and the same holds true for the cell acidification following a 101 reduction of bath HCO₃ ^– concentration. These observations indicate that the basolateral Cl^–/HCO₃ ^– exchanger was not stimulated by histamine, and that no other base transporters were activated. By contrast, the V _b response to elevation of bath K ⁺ concentration decreased, and so did the initial depolarizing V _b response to bath Cl^– substitution, while the secondary hyperpolarizing response increased. The latter observations are compatible with the notion that stimulation by histamine reduced a pH-insensitive part of the basolateral K⁺ conductance and reduced also the basolateral Cl^– conductance.     

Plasma histamine and clinical tolerance to infused histamine in normal,atopic and urticarial subjects

Five subjects with a recent history of urticaria (U), five atopic (A) subjects and a non-atopic (NA) control group were given intravenous infusions of histamine starting at 0.05 g/kg/min, increasing by 0.05 g/kg/min every 30 minutes to a maximum of 0.35 g/kg/min. Plasma histamine levels were monitored every 15 minutes. The infusion was stopped when an objective clinical endpoint was reached, involving either evidence of peripheral vasodilatation (rise of skin temperature by at least 1 °C) or a 20% fall of peak expiratory flow rate.There were no significant differences in resting plasma histamine in the three groups. Those with urticaria reached the clinical endpoint at a lower infusion rate than non-atopic subjects (U 0.22±0.02 g/kg/min; A 0.26±0.02 g/kg/min; NA 0.32±0.2 g/kg/min.p<0.008) they also received a lower total histamine dose (U 1.12±0.33 mg; A 1.42±0.38 mg, NA 2.2±0.51 mg,p<0.008). Atopic subjects with a history of asthma, eczema or rhinitis also tolerated histamine poorly, some subjects reaching a clinical endpoint while the plasma histamine level was still relatively low (U 1.52±0.4 ng/ml, A 0.85±0.19 ng/ml, NA 1.4±0.44 ng/ml,p=0.05). After the histamine infusion was stopped, the fall in the blood level of histamine was slower in urticarial subjects than in the other two groups, with a half-life of 6.2±1.3 min (A 3.0±1.2 min, NA 4.0±0.7 min,p<0.02). There were thus differences in the metabolism of histamine in our non-atopic urticarial subjects and increased histamine sensitivity in atopic subjects which require further study.     

The anti-inflammatory and analgesic profile of 6,11-dihydrodibenzo-[b.e.]-thiepin-11-one-3-acetic acid (Tiopinac)

Tiopinac displayed marked anti-inflammatory activity when given p.o. in rat models of acute and chronic inflammation. It inhibited carrageenan-induced paw edema (40 x phenylbutazone), and cotton-pellet-induced granuloma (0.8 x indomethacin). In an 18-day test, tiopinac prevented the development of adjuvant-induced arthritis (10–15 x naproxen) and had similar activity versus pre-induced arthritis. Tiopinac exhibited antiphlogistic activity in adrenalectomized rats. It did not have corticosteroid activity. Depending upon the type of analgesic test used, the potency of tiopinac varied. When given p.o. it inhibited henylquinone-induced writhing in the mouse and rat (respectively 16 and 10 x aspirin). In contrast, tiopinac had 10 times the potency of indomethacin in increasing the pain threshold when yeast-inflamed paws were compressed. The pain threshold of the noninflamed paw was not increased. Tiopinac was highly active versus pain induced by flexing the adjuvant arthritic-inflamed paw (1000 x aspirin). It was inactive in the mouse hotplate test in which opiate-like agents are active. Tiopinac, p.o., lowered yeast-induced pyrexia (130 x aspirin). Tiopinac did not have significant cardiovascular or CNS activity. Whereas the ED₅₀ versus adjuvant arthritis in rats was 0.1 mg/kg/day p.o., rats tolerated up to 20 mg/kg/day p.o. in the 8-day cotton-pellet test. Lack of anorexia and emesis in dogs with up to 30 mg/kg p.o. and mild oral activity in producing gastric erosion in acute and subacute studies in rats suggests that tiopinac may have relatively little gastrointestinal irritating activity.A preliminary presentation of this study was delivered at the Federation of American Societies of Experimental Biology Meeting, Atlantic City, N.J., 1978 (Fed. Proc.37, 662 (1978).     

The analgesic and anti-inflammatory profile of (±)-5-benzoyl-1,2-dihydro-3H-pyrrolo[1,2a]pyrrole-1-carboxylic acid (RS-37619)

RS-37619 showed highly potent analgesic activity when given p.o. in tests utilizing underlying inflammation. It inhibited phenylquinone-induced writhing in the mouse and rat (350 and 180×aspirin respectively) and the pain induced by flexing the adjuvant-inflamed rat paw ( 800×aspirin). The agent increased the pain threshold of compressed yeast-inflamed rat paws (3–10 ×naproxen). RS-37619 did not increase the pain threshold of the noninflamed paw and was inactive in the mouse hot plate test; therefore it is probably not a centrally acting or morphinelike agent. RS-37619 was also highly active p.o. in rat models of acute and chronic inflammation. It inhibited carrageenan-induced paw edema (36×phenylbutazone), cotton pellet-induced granuloma (1×indomethacin) and in an 18-day test, prevented the development of adjuvant-induced arthritis (2×naproxen). RS-37619 exhibited antiphlogistic activity in adrenalectomized rats. It did not have corticosteroid activity. When given p.o., RS-37619 lowered yeast-induced pyrexia (20×aspirin). Gastro-intestinal irritation was seen in the rat with doses 6.4 mg/kg/day p.o. The agent elicited mild CNS and cardiovascular activity only at doses far in excess of those required for analgesic and anti-inflammatory activity.A preliminary presentation of this study was delivered at the Federation of American Societies of Experimental Biology Meeting, Dallas, Texas, 1979 (Fedn Proc.38, 440 (1979)).     

β2-microglobulin and other proteins in serum and urine during preeclampsia

Summary Serum and urine samples of 5 patients with preeclampsia, an equal number with preeclampsia superimposed upon chronic pyelonephritis, and 20 normal pregnant women were analysed for fibrin split products (immunoelectrophoresis) and other proteins (Oudin-method) including ₂-microglobulin (radioimmunoassay).No fibrin split products could be detected in normal pregnant women or those with preeclampsia superimposed upon chronic pyelonephritis. Distinctly abnormal values were found, however, in the patients with preeclampsia (split D, 27.2±5.1 mg% (S.D.) in serum and 162±55mg/24 h (S.D.) in urine; split E, 0.3±0.1 mg% (S.D.) in serum and 4.2±3.1 mg%/24 h (S.D.) in the urine; fibrinogen in serum 532±146 mg% and in urine 340±78 mg/24 h (S.D.).Mean total protein excretion of patients with preeclampsia (1951±322 mg S.D./24 h) was not different from the value of patients with preeclampsia superimposed upon chronic pyelonephritis (1781±289 mg S.D./24 h).Urinary ₂-microglobulin excretion of patients with simple preeclampsia (glomerular filtration rate 100 ml/min) was 4 to 5-fold increased at term but more than 100-fold in patients whose preeclampsia was superimposed upon chronic pyelonephritis (glomerular filtration rate 30–70 ml/min).The transient urinary excretion of fibrin split products and other proteins in patients with preeclampsia and normal glomerular filtration rate is an indication of a reversible glomerular lesion, whereas the increased ₂-microglobulin excretion in this group of patients is due to a tubular lesion. In patients with preeclampsia superimposed upon chronic pyelonephritis the excretion of ₂-microglobulin is further increased which may be explained by an additional lesion of the already impaired tubular function during delivery.In serum, prealbumin was decreased to about 55% and albumin to 60% in the patients with preeclampsia and preeclampsia superimposed upon chronic pyelonephritis which cannot be explained by renal loss alone but is very likely due to an inhibition of protein synthesis in the liver cell.Contains parts of the Doctoral Thesis of D. Prüfer     

No Causal Association Between Inflammation and Chlamydia Pneumoniae in Patients with Chronic Ischemic Arterial Disease

The C-reactive protein, Chlamydia-specific IgG antibody, and fibrinogen were assayed in the serum of 159 patients with arterial disease (the arterial group) and 203 patients with heart valve prostheses (the valvular group) and no demonstrable coronary disease. In the arterial group, the Chlamydia pneumoniae antibody was 1 : 32 for 67.3% (107/159) of the patients, the C-reactive protein was elevated in 41.5% (66/159), and the fibrinogen was elevated in 27.7% (44/159). In the valvular group, the C. pneumoniae antibody was 1 : 32 for 59.1% (120/203) of the patients; the C-reactive protein was elevated in 34.0% (69/203), and the fibrinogen was elevated in 17.2% (35/203). Of 107 patients in the arterial group with C. pneumoniae titers 1 : 32, only 26 (24.3%) had elevated fibrinogen (426 ± 29 mg/dL) and 44 (41.1%) had elevated C-reactive protein (1.06 ± 0.52 mg/dL). Similarly, of the 120 patients in the valvular group with C. pneumoniae titers 1 : 32, 17 (14.2%) had elevated fibrinogen (409 ± 29 mg/dL) and 34 had elevated C-reactive protein (0.99 ± 1.1 mg/dL). Correlated poorly was C. pneumoniae with C-reactive protein and fibrinogen levels. Only the fibrinogen level could be discriminated between the arterial and the valvular group. These results suggest that no causal association exists between inflammation and C. pneumoniae. A highly significant correlation between C-reactive protein and fibrinogen levels was found.     

Activity and expression of Na+/H+ exchanger isoforms in the syncytiotrophoblast of the human placenta

The purpose of this study was to compare Na⁺/H⁺ exchanger (NHE) activity in the microvillous (MVM) and basal (BM) plasma membrane of the human placental syncytiotrophoblast and to determine the relative contribution of various NHE isoforms to this activity. Uptake of ²²Na into isolated MVM vesicles in the presence of a H⁺ gradient, at initial rate, was four- to fivefold higher than that by BM vesicles (214±28 vs. 49±9 pmol/mg protein per 30 s, respectively, means±SEM, n=8, 6, P<0.001). The ²²Na uptake by MVM, but not by BM, was reduced in the absence of a H⁺ gradient and in the presence of 500 M amiloride. To determine the contribution of NHE1, NHE2 and NHE3 isoforms to NHE activity in MVM, we investigated the effect of amiloride analogues which show isoform selectivity. HOE 694, an analogue selective for NHE1 at low concentrations, inhibited ²²Na uptake with an EC₅₀ of 0.13±0.05 M (n=6), whereas S3226, an analogue selective for NHE3 at low concentrations had an EC₅₀ of 3.01±0.85 M (n=5). To investigate this further, we measured recovery of syncytiotrophoblast intracellular pH (pH_i) from an acid load using a H⁺-selective, fluorescent dye (BCECF) loaded into isolated intact placental fragments. This recovery was blocked in the absence of Na⁺ and the presence of amiloride (500 M) and concentrations of HOE 694 and S3226 were comparable to those used in vesicle experiments. Overall these data show that under the conditions used NHE activity in the term placental syncytiotrophoblast is absent from BM. NHE activity in the MVM is attributable predominantly to NHE1.     

Differential involvement of central 5-HT<Subscript>1B</Subscript> and 5-HT<Subscript>3</Subscript> receptor subtypes in the antinociceptive effect of paracetamol

Objective: We investigated the effect of pre-treatment with ondansetron or CP 93129 (a 5-HAT_1B agonist) on the antinociceptive activity of paracetamol and the changes in central 5-HT₃ receptors induced by paracetamol alone or co-administered with ondansetron.Materials and Subjects: Male Wistar rats (eight per group) were injected with ondansetron (2 and 4 mg/kg s.c.) or CP 93129 (0.5, 1 and 2 mg/kg s.c.) 15 min before paracetamol (400 mg/kg, i.p.).Methods: Pain threshold was evaluated in the hot-plate or in the paw pressure test 30 min after the last treatment. 5-HT₃ receptor binding capacity was measured in the frontal cortex, temporal-parietal cortex and midbrain by means of radioligand binding technique. Statistical analysis was done using ANOVA followed by Student-Newman-Keuls test and 2 X 2 factorial analysis when appropriate.Results: Pre-treatment with ondansetron, at doses of 2 and 4 mg/kg, did not affect the antinociceptive activity of paracetamol in the hot-plate test and in the paw pressure test. Paracetamol did not change the characteristics of 5-HT₃ receptors in all the areas investigated. Ondansetron (4 mg/kg s.c) per se significantly increased the 5-HT₃ receptor number in the areas used, the effect not being modified by co-administration with paracetamol. On the other hand, CP 93129 (2 mg/kg s.c.) significantly prevented the effect of paracetamol in both algesimetric tests used.Conclusions: Our data indicate that 5-HT_1B but not 5-HT₃ receptors are involved in the antinociceptive effect of paracetamol in our experimental conditions.Received 25 November 2002; returned 10 April 2003; accepted by G. Geisslinger 22 April 2003     

Adrenaline-stimulated,aspirin-sensitive synthesis of histamine in the rat

The intravenous injection of 40 g/kg of adrenaline raised total rat lung histamine from 5.3±0.7 g, to 8.4±0.7 g and rat skin histamine from 624±51 g to 835±85 within 5 min. These changes were no longer apparent after 10 min. Stomach histamine was unaffected. Blood drawn 2 min after the injection of adrenaline failed to show an increased content of histamine. Rats given 1 mg/kg of compound 48/80, had greatly elevated levels of histamine in blood, but exhibited no increase in lung histamine. This result, as well as the extent of the increase of histamine observed in skin, which cannot be accounted for in any other way, point towards stepped-up local synthesis as the origin of the effect of adrenaline. Aspirin (20 mg/kg, intravenously 10 min prior to adrenaline), prevented increases of skin histamine. Evidence suggesting mast cells as the site of action of adrenaline, is discussed.     

The involvement of the HO-1 pathway in the anti-inflammatory action of a sulfated polysaccharide isolated from the red seaweed Gracilaria birdiae

Objectives

The aim of this study was to investigate the involvement of the hemoxigenase-1 (HO-1) pathway in the anti-inflammatory action of a sulfated polysaccharide from the red seaweed Gracilaria birdiae (SP-Gb).

Methods

SP-Gb (5, 10 and 20?mg/kg) was administered to Wistar rats in a peritonitis model using carrageenan or a paw edema model using carrageenan or dextran. To analyze the involvement of HO-1 in the anti-inflammatory activity of SP-Gb, the animals were pretreated subcutaneously with a specific HO-1 inhibitor (ZnPP IX). To evaluate the systemic effects, SP-Gb (10?mg/kg) was administered to mice intraperitoneally before waiting for 48?h or for 14?days.

Results

SP-Gb (10?mg/kg) caused an anti-inflammatory effect that was evidenced by a decrease in leukocytes in the peritoneal cavity. SP-Gb also reduced the paw edema induced by carrageenan and inhibited the paw edema induced by dextran in the first half-hour. After being inhibited by ZnPP IX, the anti-inflammatory effect of SP-Gb on carrageenan-induced rat paw edema was not observed. SP-Gb did not cause mortality or significant changes in the biochemical, hematological and histopathological parameters.

Conclusion

SP-Gb may be used as a tool for further investigations into the inflammatory processes associated with the hemoxigenase-1 pathway.     

Histamine release with intravenous narcotics: Protective effects of H1 and H2-receptor antagonists

Summary High dose narcotic anesthesia with fentanyl or morphine is not associated with significant direct myocardial depression. Morphine is reported to produce arteriolar dilatation and a decrease in SVR (probably due to histamine release) while fentanyl is not. Studies were undertaken to determine if morphine or fentanyl caused histamine release; if such a release correlated with hemodynamic changes, and if H₁ and H₂ antagonists could provide protection. In a randomized double blind study of 40 patients in 4 groups, patients who received morphine (1 mg/kg) demonstrated significant increases in plasma histamine (880±163 to 7,437±2,684 pg/ml–p<0.01) accompanied by an increase in CI (2.4±0.2 to 3.0±0.2 l/min/m²–p<0.01) and decreases in (88±4 to 61±4 torr–p<0.01) and SVR (15.5±1 to 9.0±1 torr-l-min^–1 p<0.01). The prior administration of H₁ (dyphenhydramine 1 mg/kg) and H₂ (cimetidine 4 mg/kg) antagonists provided significant protection (SVR 17.4±1 to 14.6±1 torr-l-min^–1–p<0.05) although histamine increased comparably (1,059±22 to 7,653±4,242 pg/ml–p<0.05). In a separate study, seven patients receiving fentanyl 50 µg/kg showed no histamine changes (935±51 to 685±51 pg/ml) and no significant hemodynamic response. Eight patients receiving morphine 1 mg/kg again showed significant increases in plasma histamine (880±163 to 7,480±2,230 pg/ml–p<0.05) which collelated with the decrease in SVR (r=0.81). These data demonstrate that morphine releases histamine in amounts which correlate with the hemodynamic changes seen. Prior administration of H₁ and H₂ histamine antagonists provide significant protection — more so than either alone. Fentanyl produced no histamine release which may account for much of the cardiovascular stability reported with this drug.     

pH dependence of K+ conductances of rat cortical collecting duct principal cells

The K⁺ channels of the principal cells of rat cortical collecting duct (CCD) are pH sensitive in excised membranes. K⁺ secretion is decreased with increased H⁺ secretion during acidosis. We examined whether the pH sensitivity of these K⁺ channels is present also in the intact cell and thus could explain the coupling between K⁺ and H⁺ secretion. Membrane voltages (V _m), whole-cell conductances (g _c), and single-channel currents of K⁺ channels were recorded from freshly isolated CCD cells or isolated CCD segments with the patch-clamp method. Intracellular pH (pH_i) was measured using the pH-sensitive fluorescent dye 2-7-bis(carboxyethyl)-5-6-carboxyfluorescein (BCECF). Acetate (20 mmol/l) had no effect on V _m, g _c, or the activity of the K⁺ channels in these cells. Acetate, however, acidified pH_i slightly by 0.17±0.04 pH units (n=19). V _m depolarized by 12±3 mV (n=26) and by 23±2 mV (n=66) and g _c decreased by 26±5% (n=13) and by 55±5% (n=12) with 3–5 or 8–10% CO₂, respectively. The same CO₂ concentrations decreased pH_i by 0.49±0.07 (n=15) and 0.73±0.11 pH units (n=12), respectively. Open probability (P _o) of all four K⁺ channels in the intact rat CCD cells was reversibly inhibited by 8–10% CO₂. pH_i increased with the addition of 20 mmol/l NH₄ ⁺/NH₃ by a maximum of 0.64±0.08 pH units (n=33) and acidified transiently by 0.37±0.05 pH units (n=33) upon NH₄ ⁺/NH₃ removal. In the presence of NH₄ ⁺/NH₃ V _m depolarized by 16±2 mV (n=66) and g _c decreased by 26±7% (n=16). The activity of all four K⁺ channels was also strongly inhibited in the presence of NH₄ ⁺/NH₃. The effect of NH₄ ⁺/NH₃ on V _m and g _c was markedly increased when the pH of the NH₄ ⁺/NH₃-containing solution was set to 8.5 or 9.2. From these data we conclude that cellular acidification in rat CCD principal cells down-regulates K⁺ conductances, thus reduces K⁺ secretion by direct inhibition of K⁺ channel activity. This pH dependence is present in all four K⁺ channels of the rat CCD. The inhibition of K⁺ channels by NH₄ ⁺/NH₃ is independent of changes in pH_i and rather involves an effect of NH₃.     

Anti-inflammatory and antipyretic effects of boldine

Boldine, and antioxidant alkaloid isolated fromPeumus boldus, exhibits a dose-dependent anti-inflammatory activity in the carrageenan-induced guinea pig paw edema test with an oral ED₅₀ of 34 mg/kg. Boldine also reduces bacterial pyrogen-induced hyperthermia in rabbits to an extent which varied between 51% and 98% at a dose of 60 mg/kg p.o.In vitro studies carried out in rat aortal rings revealed that boldine is an effective inhibitor of prostaglandin biosynthesis, promoting 53% inhibition at 75 M. The latterin vitro effect may be mechanistically linked to the anti-inflammatory and antipyretic effects of boldine exertedin vivo.