Response of bronchial smooth muscle to mast cell degranulation in situ

We studied the response of bronchial smooth muscle to mast cell degranulation with Ascaris suum antigen (AA) and compound 48/80 (48/80) in 26 mongrel dogs in situ. Bronchial smooth muscle response was measured isometrically in situ from a segment of the right middle lobe bronchus; tracheal response was monitored isometrically as a control. After intra-arterial (ia) injection of AA into the bronchial circulation, bronchial contraction preceded tracheal contraction by 19.2 +/- 4.6 s (P less than 0.002). Bronchial contraction to AA (21.7 +/- 3.4 g) was substantially greater than to 48/80 (10.5 +/- 1.8 g, P less than 0.05) corresponding to differences in maximal systemic histamine concentrations (146 +/- 24.1 vs. 1000 +/- 236 ng/ml, P less than 0.01). In 5 dogs, the effect of leukotriene D4 (LTD4) and FPL 55712 was studied. Injection of 10(-8) mol ia LTD4 caused no bronchial contraction. In four dogs, 10(-7) mol FPL 55712 caused no bronchial relaxation after initial precontraction during immune degranulation with AA; intravenous chlorpheniramine (5 mg/kg) caused 69.7 +/- 9.4% relaxation. We demonstrate a model that permits selective immune degranulation of a single major resistance bronchus in situ. We conclude that AA-induced degranulation in dogs caused bronchial contraction predominantly by secretion of preformed mediator.     

Stabilization of mast cells by heme oxygenase-1: an anti-inflammatory role

This study examined the role of bilirubin in heme oxygenase (HO)-1-mediated amelioration of mast cell (MC)-elicited inflammatory responses. Pretreatment of rats with an intraperitoneal injection of hemin, an inducer of HO-1, evolved a marked induction of the enzyme in MCs. Intravital videomicroscopy revealed that hemin pretreatment attenuated compound 48/80-elicited degranulation of MCs and resultant leukocyte adhesion in venules. Superfusion with biliverdin or bilirubin, but not with carbon monoxide (CO), another product of the HO reaction, mimicked suppressive actions of the HO-1 induction on both the cell degranulation and leukocyte adhesion elicited by the stimulus, suggesting a requirement of the enzyme reaction to generate bilirubin in the inhibitory mechanisms. Such MC-desensitizing actions of bilirubin were observed in primary-cultured MCs and reproduced irrespective of the choice of stimuli, such as compound 48/80, calcium ionophore, and anti-IgE serum. Furthermore, MC-stabilizing effects of HO-1 were reproduced by the gene transfection of the enzyme into mastocytoma cell line RBL2H3. These results suggest that bilirubin generated through HO-1 serves as an anti-inflammatory substance that desensitizes MCs and ameliorates leukocyte recruitment.     

Elevated blood glucose after compound 48/80 treatment is not related to hepatic mast cell degranulation in rats

Blood glucose, hepatic glycogen, and the histological integrity of hepatic mast cells, were evaluated in anesthetized rats receiving iv injections of 0.125 mg/kg body weight compound 48/80 (a mast cell degranulator) and/or of 0.001 to 10.0 mg/kg body weight lodoxamide tromethamine (an inhibitor of mast cell degranulation). A nonglucogenic dose of lodoxamide, 0.001 mg/kg body weight, prevented dissipation of histochemically demonstrable fluorescence in mast cells (degranulation) without inhibiting compound 48/80-induced hyperglycemia and hepatic glycogenolysis. These results suggest that this glucotropic response is independent of compound 48/80-evoked release of mediators such as serotonin from mast cells.     

Inhibitory function of Shikonin on MRGPRX2-mediated pseudo-allergic reactions induced by the secretagogue

BackgroundMast cells (MCs) are crucial effectors in allergic disorders by secreting inflammatory mediators. The Mas-related G-protein-coupled receptor X2 (Mrgprx2) was shown to have a key role in IgE-independent allergic reactions. Therefore, potential drug candidates that directly target Mrgprx2 could be used to treat pseudo-allergic diseases. Shikonin, an active ingredient derived from Lithospermum erythrorhizon Sieb. et Zucc has been used for its anti-inflammatory properties since ancient China.PurposeTo investigate the inhibitory effects of Shikonin on IgE-independent allergy both in vitro and in vivo, as well as the mechanism underlying its effects.Methods/study designsThe anti-anaphylactoid activity of Shikonin was evaluated in PCA and systemic anaphylaxis models, Calcium imaging was used to assess intracellular Ca²⁺ mobilization. The release of cytokines and chemokines was measured using enzyme immunoassay kits. Western blot analysis was conducted to investigate the molecules of PLCγ-PKC-IP3 signaling pathway. The analytical method of surface plasmon resonance was employed to study the interaction between Shikonin and potential target protein Mrgprx2.ResultsShikonin can suppress compound 48/80 (C48/80)-induced PCA, active systemic anaphylaxis, and MCs degranulation in mice in a dose-dependent manner. In addition, Shikonin reduced C48/80-induced calcium flux and suppressed LAD2 cell degranulation via PLCγ-PKC-IP3 signaling pathway. Moreover, Shikonin was found to inhibit C48/80-induced Mrgprx2 expression in HEK cells, displaying specific interactions with the Mrgprx2 protein.ConclusionShikonin could be a potential antagonist of Mrgprx2, thereby inhibiting pseudo-allergic reactions through Ca²⁺ mobilization.     

Influence of the intensity of a conditioning contraction on the subsequent twitch torque and maximal voluntary concentric torque

This study aimed to clarify the influence of the intensity of a conditioning contraction on subsequent isometric twitch and maximal voluntary concentric torques. Subjects (n=12men) performed voluntary isometric plantar flexion for six seconds as a conditioning contraction, at intensities of 40%, 60%, 80% and 100% of a maximal voluntary isometric contraction (MVIC). Before and immediately after the conditioning contraction, isometric twitch and maximal voluntary concentric (180°/s) plantar flexion torques were determined. Surface electromyograms were recorded from the triceps surae muscles and M-wave amplitudes and root-mean-square values of the electromyographic signals (RMS(EMG)) were calculated. The isometric twitch torque increased significantly after conditioning contraction at all intensities (P<0.05), whereas maximal voluntary concentric torque increased significantly only at 80% and 100% MVIC conditions (P<0.05). It is concluded that during a six second conditioning contraction, the effect of the intensity of a conditioning contraction on subsequent torque development is different between an isometric twitch and maximal voluntary concentric contractions, with the latter being less affected.     

Proliferative potential of murine peritoneal mast cells after degranulation induced by compound 48/80, substance P, tetradecanoylphorbol acetate, or calcium ionophore A23187.

Proliferative potential of degranulated mast cells was investigated. Mast cells were collected from the peritoneal cavity of mice, and degranulation was induced by compound 48/80, substance P, 12-O-tetradecanoylphorbol 13-acetate (TPA), or calcium ionophore A23187. The potentiality of colony formation in methylcellulose was not reduced by treatment of various concentrations of compound 48/80, substance P and TPA. When degranulation was induced by compound 48/80, substance P or TPA, proportion of highly degranulated mast cells containing less than five granules was rather small. In contrast, considerable proportion of highly degranulated mast cells was obtained after the treatment with the low concentration (0.1 microgram/ml) of A23187. These highly degranulated mast cells, which were individually picked up by the micromanipulator, proliferated not only in methylcellulose but also in the skin of mast cell-deficient WBB6F1-W/Wv mice. Inasmuch as we have already shown the proliferation of IgE-sensitized and Ag-stimulated mast cells, degranulated mast cells appear to retain the proliferative potential in general.     

Late phase bronchial obstruction following nonimmunologic mast cell degranulation

Immunologic degranulation of airway mast cells after antigen inhalation produces early and late airway obstructions in allergic sheep. In this study we determined whether nonimmunologic degranulation of airway mast cells by inhalation of compound 48/80 had similar effects. In five sheep, pulmonary flow resistance (RL), thoracic gas volume (Vtg), and arterial O2 tension (Pao2) were determined prior to and at predetermined times after inhalation of 48/80 aerosol. Immediately after challenge mean specific lung resistance (sRL = RL X Vtg) increased by 259% and mean Pao2 decreased by 29%. All values returned to normal by 3 h. By 5-h postchallenge sRL again increased significantly; this second increase in sRL (92% above base line) was maximal at 7 h and was accompanied by a 17% drop in Pao2. In these same sheep inhalation of Ascaris suum antigen produced comparable early changes in sRL, but the onset of the late response was somewhat delayed and more pronounced. In a second group of sheep (n = 5), pretreatment with the mast cell stabilizer cromolyn sodium prevented both early and late responses by compound 48/80. Pretreatment with the histamine H1-antagonist chlorpheniramine had no significant effect on either response, whereas pretreatment with FPL 55712, an antagonist of slow-reacting substance of anaphylaxis (SRS-A), slightly but not significantly attenuated the early response and completely prevented the late response. We conclude that, like immunologic stimuli, nonimmunologic mast cell degranulation produces early and late bronchial obstructions in allergic sheep; that these responses are mediator dependent; and that while histamine and SRS-A contribute to the early response, it is the early appearance of SRS-A which is an important prerequisite for the late response.     

Bronchial smooth muscle mechanics of a canine model of allergic airway hyperresponsiveness.

Although we have reported that tracheal smooth muscle from sensitized dogs shows altered mechanical properties, we did not know, because of technical difficulties with the preparation, whether similar changes occur in the properties of sensitized central bronchial smooth muscle (BSM), the site at which the acute asthmatic response is believed to develop. We have now succeeded in developing a cartilage-free BSM preparation that retains optimal mechanical properties. Such strips were obtained from mongrel dogs that had been sensitized to ragweed pollen. Controls were littermates injected with adjuvant alone. Length-tension relationships were obtained for both control and sensitized BSM strips (CBSM and SBSM, respectively). The maximal active stresses were the same (P greater than 0.05) when normalized to muscle fraction in total tissue cross-sectional area [6.2 +/- 0.6 x 10(4) and 5.9 +/- 0.6 x 10(4) (SE) for SBSM and CBSM, respectively]. This suggests that optimal tension is an insensitive indicator of bronchial hyperresponsiveness and that isotonic studies might be more revealing. The maximal shortening velocity (Vo) for SBSM at 2 s [0.35 +/- 0.017 (SE) lo/s, where lo signifies optimal muscle length], in the course of a 10-s contraction, was significantly greater (P less than 0.05) than Vo measured for CBSM (0.27 +/- 0.015 lo/s). However, Vo did not differ at the 8-s point of contraction. The sensitized group demonstrated a statistically significantly greater maximal shortening capacity (0.67 +/- 0.04 lo) than the control group (0.51 +/- 0.04 lo). At 2 s of contraction, 80% of maximal SBSM shortening had been completed and was significantly greater than for CBSM.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunomodulatory activity of boswellic acids of Boswellia serrata Roxb

Extract of gum resin of B. serrata containing 60% acetyl 11-keto beta boswellic acid (AKBA) along with other constituents such as 11-keto beta-boswellic acid (KBA), acetyl beta-boswellic acid and beta-boswellic acid has been evaluated for antianaphylactic and mast cell stabilizing activity using passive paw anaphylaxis and compound 48/80 induced degranulation of mast cell methods. The extract inhibited the passive paw anaphylaxis reaction in rats in dose-dependant manner (20, 40 and 80 mg/kg, po). However, the standard dexamethasone (0.27 mg/kg, po) revealed maximum inhibition of edema as compared to the extract. A significant inhibition in the compound 48/80 induced degranulation of mast cells in dose-dependant manner (20, 40 and 80 mg/kg, po) was observed thus showing mast cell stabilizing activity. The standard disodium cromoglycate (50 mg/kg, ip) was found to demonstrate maximum per cent protection against degranulation as compared to the extract containing 60% AKBA. The results suggest promising antianaphylactic and mast cell stabilizing activity of the extract.     

Exogenous dendritic cell homing to draining lymph nodes can be boosted by mast cell degranulation

Dendritic cells (DCs), as potent antigen presenting cells, are increasingly used for immunotherapeutic approaches, predominantly in oncology. Low efficiency of injected Ag-pulsed DC homing to draining lymph nodes (DLNs) is one of the factors that affect the efficacy of therapy. As Langerhans cell emigration was enhanced after skin mast cell degranulation, we investigated the effect of local mast cell activation on exogenous bone marrow-derived DCs (BM-DCs) homing to DLNs. Product of activated MC/9 mast cells enhanced chemotaxis of BM-DCs to CCL21 in vitro. Intradermal injection of compound 48/80 (c48/80) induced local skin mast cell obvious degranulation and boosted exogenous BM-DC homing to DLNs. Both Ag-specific lymphocyte proliferation and TH1/TH2 cytokine production increased after HBsAg-pulsed BM-DC was injected into c48/80 pretreated mice. These results suggest that transferred DC homing to DLNs promoted by local mast cell degranulation may have potential application to improve DC-based immunotherapy.     

Effect of disodium cromoglycate on mast cell-mediated immediate-type allergic reactions

We investigated the effect of disodium cromoglycate (DSCG) on mast cell-mediated immediate-type hypersensitivity. DSCG inhibited systemic allergic reaction induced by compound 48/80 dose-dependently. Passive cutaneous anaphylaxis was inhibited by 71.6% by oral administration of DSCG (1 g/kg). When DSCG was pretreated at concentration rang from 0.01-1000 g/kg, the serum histamine levels were reduced in a dose dependent manner. DSCG also significantly inhibited histamine release from rat peritoneal mast cell (RPMC) by compound 48/80. We confirmed that DSCG inhibited compound 48/80-induced degranulation of RPMC by alcian blue/nuclear fast red staining. In addition, DSCG showed a significant inhibitory effect on anti-dinitrophenyl IgE-mediated tumor necrosis factor-alpha production. These results indicate that DSCG inhibits mast cell-mediated immediate-type allergic reaction.     

姜黄素对小鼠离体十二指肠平滑肌舒缩活动的影响

目的:本研究采用小鼠离体十二指肠平滑肌观察姜黄素对胃肠道蠕动的影响,探讨其作用机制。方法:取小鼠离体十二指肠平滑肌条,放入37℃Krebs液浴槽中,通入95%氧气和5%二氧化碳混合气体,分组进行下列实验:对照组和分别加入10-40 M姜黄素组,测量记录十二指肠平滑肌的自主收缩变化;另取一组平滑肌条,分对照组、乙酰胆碱组、乙酰胆碱+姜黄素组、阿托品组、阿托品+姜黄素组,采用张力换能器连接多通道生理信号采集处理系统,测量比较十二指肠平滑肌舒缩的变化。结果:小鼠十二指肠平滑肌加入姜黄素孵育后,其自主收缩幅度有明显下降(P0.01),而且降低的幅度与姜黄素剂量相关;给与乙酰胆碱引起十二指肠收缩后,再加姜黄素孵育,十二指肠平滑肌的收缩幅度明显的下降(P0.01);给予阿托品引起小鼠平滑肌舒张后,再给予姜黄素孵育,平滑肌收缩幅度进一步降低。结论:姜黄素对小鼠离体十二指肠平滑肌具有直接舒张作用。     

The cannabinoid CB2 receptor selective agonist JWH133 reduces mast cell oedema in response to compound 48/80 in vivo but not the release of beta-hexosaminidase from skin slices in vitro

In a recent study so far published in abstract form, it was reported that the CB(2) receptor selective agonist AM1241 diminishes oedema produced as a result of mast cell degranulation in vivo. It is, however, not known whether other structurally different CB(2) agonists share this effect, and whether this is due to a direct effect on mast cell function. In the present study, we have investigated the effects of JWH133, a CB(2) receptor selective agonist, together with the anti-inflammatory agent palmitoylethanolamide and its analogue palmitoylisopropylamide, on compound 48/80-induced oedema and degranulation in vivo and in vitro. JWH133 (20 and 200 microg/mouse i.p.) significantly reduced the ability of compound 48/80 to induce oedema in vivo in the anaesthetised mouse following its injection into the ear pinna. Palmitoylethanolamide (200 microg/mouse i.p) also reduced the response to compound 48/80, whereas no firm conclusions could be drawn for palmitoylisopropylamide (20 and 200 microg/mouse i.p.). The CB(2) selective antagonist/inverse agonist SR144528 (60 microg/mouse i.p.) appeared to produce anti-inflammatory effects per se in this model, making it hard to interpret the effects of JWH133 in terms of CB(2) receptor mediated activation. In contrast to the situation in vivo, neither JWH133 (0.3 and 3 microM) nor palmitoylethanolamide (10 microM) affected mast cell degranulation, measured by following the release of the granular protein beta-hexosaminidase, produced by compound 48/80 in vitro in mouse skin slices. The two compounds were also ineffective in inhibiting the binding of [(3)H]pyrilamine to histamine H(1) receptors in vitro. It is concluded that the ability of JWH133 to affect mast cell dependent inflammation in vivo may be mediated by an indirect action upon the mast cells.     

Modulation of cardiac mast cell-mediated extracellular matrix degradation by estrogen

There are fundamental differences between males and females with regard to susceptibility to heart disease. Although numerous animal models of heart failure have demonstrated that premenopausal females are afforded cardioprotection and, therefore, fare better in the face of cardiac disease than their male counterparts, many questions as to how this occurs still exist. Recently, we showed that 1) increased mast cell density is associated with adverse ventricular remodeling and 2) chemically induced mast cell degranulation using compound 48/80 resulted in remarkable changes in matrix metalloproteinase (MMP) activity, cardiac collagen structure, and cardiac diastolic function in normal male rats. With the known gender differences in cardiac disease in mind, we sought to examine the effects of chemically induced cardiac mast cell degranulation in isolated, blood-perfused hearts of intact female rats, ovariectomized female rats, and ovariectomized female rats treated with 17beta-estradiol. In response to mast cell degranulation, no significant differences in cardiac function, MMP-2 activity, or collagen volume fraction were observed between intact female rats and ovariectomized female rats treated with estrogen. In the ovariectomized female group, a significant rightward shift in the left ventricular pressure-volume relation, accompanied by a marked 133% increase in active MMP-2 values over that in the intact female group, was noted after treatment with compound 48/80 (P < or = 0.05), along with a significant reduction in collagen volume fraction below control (0.46 +/- 0.23 vs. 0.73 +/- 0.13%, P < or = 0.05). These findings indicate that estrogen's cardioprotective role can be partially mediated by its effects on cardiac mast cells, MMPs, and the extracellular matrix.     

腹腔镜手术联合微生态制剂对结直肠癌患者肠道菌群和肠道屏障功能的影响

目的观察腹腔镜手术联合微生态制剂对结直肠癌患者肠道菌群和肠道屏障功能的影响,为临床治疗提供依据。方法选择我院2016年12至2018年12月收治的84例结直肠癌患者为研究对象。入选患者分为观察组和对照组。观察组患者采用腹腔镜手术联合口服益生菌治疗,对照组患者单纯采用腹腔镜手术治疗。比较两组患者术后恢复情况、并发症情况、肠道菌群变化和肠道屏障功能。结果观察组患者第1次完全进食时间、术后住院总时间(d)均短于对照组(9.54±0.52 vs 11.56±0.24、11.61±2.14 vs 14.94±3.65,P<0.05);观察组患者术后并发症总发生率低于对照组(9.5%vs 28.6%,P<0.05)。观察组患者术后第1次排便时肠道乳杆菌、双歧杆菌数量(lg CFU/g)大于对照组(7.21±0.35 vs 6.78±0.21、7.12±0.23 vs 6.84±0.25,P<0.05),大肠埃希菌、球杆菌数量低于对照组(8.12±0.56 vs 9.55±0.54、8.24±0.24 vs 8.85±0.25,P<0.05)。观察组患者术后第15天肠道乳杆菌、双歧杆菌数量大于对照组(9.51±0.56 vs 8.21±0.45、9.61±0.44 vs 7.85±0.23,P<0.05),大肠埃希菌、球杆菌数量低于对照组(7.22±0.36 vs 9.15±0.35、7.68±0.54 vs 8.25±0.55,P<0.05)。观察组患者术后第15天粪便sIgA水平(mg/g)大于对照组(1.21±0.13 vs 1.05±0.14,P<0.05);血清D-乳酸、尿L/M水平(μg/mL)低于对照组(5.48±0.85 vs 0.62±0.54、3.24±0.28 vs 2.68±0.54,P<0.05)。结论腹腔镜手术联合益生菌制剂可纠正并改善结直肠癌患者术后肠道微生态失调,修复并增强肠道屏障功能。     

Involvement of veratridine-induced increase of reverse Na(+)/Ca(2+) exchange current in intracellular Ca(2+) overload and extension of action potential duration in rabbit ventricular myocytes

The objectives of this study were to investigate the effects of veratridine (VER) on persistent sodium current (I(Na.P)), Na(+)/Ca(2+) exchange current (I(NCX)), calcium transients and the action potential (AP) in rabbit ventricular myocytes, and to explore the mechanism in intracellular calcium overload and myocardial contraction enhancement by using whole-cell patch clamp recording technique, visual motion edge detection system, intracellular calcium measurement system and multi-channel physiological signal acquisition and processing system. The results showed that I(Na.P) and reverse I(NCX) in ventricular myocytes were obviously increased after giving 10, 20 μmol/L VER, with the current density of I(Na.P) increasing from (-0.22 ± 0.12) to (-0.61 ± 0.13) and (-2.15 ± 0.14) pA/pF (P < 0.01, n = 10) at -20 mV, and that of reverse I(NCX) increasing from (1.62 ± 0.12) to (2.19 ± 0.09) and (2.58 ± 0.11) pA/pF (P < 0.05, n = 10) at +50 mV. After adding 4 μmol/L tetrodotoxin (TTX), current density of I(Na.P) and reverse I(NCX) returned to (-0.07 ± 0.14) and (1.69 ± 0.15) pA/pF (P < 0.05, n = 10). Another specific blocker of I(Na.P), ranolazine (RAN), could obviously inhibit VER-increased I(Na.P) and reverse I(NCX). After giving 2.5 μmol/L VER, the maximal contraction rate of ventricular myocytes increased from (-0.91 ± 0.29) to (-1.53 ± 0.29) μm/s (P < 0.01, n = 7), the amplitude of contraction increased from (0.10 ± 0.04) to (0.16 ± 0.04) μm (P < 0.05, n = 7), and the baseline of calcium transients (diastolic calcium concentration) increased from (1.21 ± 0.08) to (1.37 ± 0.12) (P < 0.05, n = 7). After adding 2 μmol/L TTX, the maximal contraction rate and amplitude of ventricular myocytes decreased to (-0.86 ± 0.24) μm/s and (0.09 ± 0.03) μm (P < 0.01, n = 7) respectively. And the baseline of calcium transients reduced to (1.17 ± 0.09) (P < 0.05, n = 7). VER (20 μmol/L) could extend action potential duration at 50% repolarization (APD(50)) and at 90% repolarization (APD(90)) in ventricular myocytes from (123.18 ± 23.70) to (271.90 ± 32.81) and from (146.94 ± 24.15) to (429.79 ± 32.04) ms (P < 0.01, n = 6) respectively. Early afterdepolarizations (EADs) appeared in 3 out of the 6 cases. After adding 4 μmol/L TTX, APD(50) and APD(90) were reduced to (99.07 ± 22.81) and (163.84 ± 26.06) ms (P < 0.01, n = 6) respectively, and EADs disappeared accordingly in 3 cases. It could be suggested that: (1) As a specific agonist of the I(Na.P), VER could result in I(Na.P) increase and intracellular Na(+) overload, and subsequently intracellular Ca(2+) overload with the increase of reverse I(NCX). (2) The VER-increased I(Na.P) could further extend the action potential duration (APD) and induce EADs. (3) TTX could restrain the abnormal VER-induced changes of the above-mentioned indexes, indicating that these abnormal changes were caused by the increase of I(Na.P). Based on this study, it is concluded that as the I(Na.P) agonist, VER can enhance reverse I(NCX) by increasing I(Na.P), leading to intracellular Ca(2+) overload and APD abnormal extension.     

Resistance exercise load does not determine training-mediated hypertrophic gains in young men

We have reported that the acute postexercise increases in muscle protein synthesis rates, with differing nutritional support, are predictive of longer-term training-induced muscle hypertrophy. Here, we aimed to test whether the same was true with acute exercise-mediated changes in muscle protein synthesis. Eighteen men (21 ± 1 yr, 22.6 ± 2.1 kg/m(2); means ± SE) had their legs randomly assigned to two of three training conditions that differed in contraction intensity [% of maximal strength (1 repetition maximum)] or contraction volume (1 or 3 sets of repetitions): 30%-3, 80%-1, and 80%-3. Subjects trained each leg with their assigned regime for a period of 10 wk, 3 times/wk. We made pre- and posttraining measures of strength, muscle volume by magnetic resonance (MR) scans, as well as pre- and posttraining biopsies of the vastus lateralis, and a single postexercise (1 h) biopsy following the first bout of exercise, to measure signaling proteins. Training-induced increases in MR-measured muscle volume were significant (P < 0.01), with no difference between groups: 30%-3 = 6.8 ± 1.8%, 80%-1 = 3.2 ± 0.8%, and 80%-3= 7.2 ± 1.9%, P = 0.18. Isotonic maximal strength gains were not different between 80%-1 and 80%-3, but were greater than 30%-3 (P = 0.04), whereas training-induced isometric strength gains were significant but not different between conditions (P = 0.92). Biopsies taken 1 h following the initial resistance exercise bout showed increased phosphorylation (P < 0.05) of p70S6K only in the 80%-1 and 80%-3 conditions. There was no correlation between phosphorylation of any signaling protein and hypertrophy. In accordance with our previous acute measurements of muscle protein synthetic rates a lower load lifted to failure resulted in similar hypertrophy as a heavy load lifted to failure.     

Mast cells are not required for anaphylatoxin-induced ileal smooth muscle contraction

The complement-derived anaphylatoxin peptides, C3a and C5a, have long been considered to manifest their spasmogenic activities primarily through stimulation of mast cells. Although mast cells represent the major non-circulating repository for histamine, these cells also elaborate a number of additional, highly potent spasmogenic mediators derived from arachidonic acid. The same lipid mediators can be released by many other cell types. As a result, evaluation of the role of mast cells in anaphylatoxin-dependent responses cannot be based exclusively upon an analysis of the mediators released. We evaluated the role of mast cells in anaphylatoxin-induced ileal smooth muscle contractions by testing isolated segments of ileal tissues derived from genetically mast cell-deficient mice and their congenic normal (+/+) littermates. Isolated tissues from either congenic normal (+/+) or mast cell-deficient Sl/Sld mice responded similarly to acetylcholine, histamine, serotonin, prostaglandin E2, and the thromboxane A2 analog, U-46619. At 1 microgram/ml, histamine induced contractions of greater magnitude in tissues from mast cell-deficient animals; however, this mediator also desensitized the tissues to repeat challenge with histamine at the same concentration. C5a at 1 nM resulted in contractions equivalent to approximately 50% of the maximal KCl response; normal and mast cell-deficient tissues responded in a similar manner. C5a also released histamine from the normal mouse ileum, in addition to causing contraction of the tissues. C3a at 200 nM also produced similar contractile responses in both +/+ and S1/S1d tissues. These studies show that the anaphylatoxin peptides C3a and C5a are capable of contracting smooth muscle-containing tissues by a mechanism completely independent of mast cells. In addition, we also demonstrated that mast cell degranulation does not necessarily provoke ileal contraction. Thus compound 48/80, a mast cell degranulating agent unrelated to the anaphylatoxins, did not induce contractions in ileal tissues, even when used at concentrations as high as 100 micrograms/ml. Compound 48/80 did release histamine from the +/+ ileum, however, indicating that the agent was able to cause degranulation of ileal mast cells. Taken together, these data indicate that spasmogenic responses to anaphylatoxins (and possibly other agents) that are associated with mast cell degranulation need not necessarily require mast cell mediator release for their expression.     

Biochemical effects of 12-O-tetradecanoylphorbol-13-acetate, retinoic acid, phenobarbital, and 5-azacytidine on a normal rat liver epithelial cell line

Compound 48/80 (poly-p-methoxyphenethylmethylamine), an agent commonly used to trigger degranulation of mast cells, at concentrations of 5-20 micrograms/ml suppresses the proliferation of L1210 and Friend leukemic cells in vitro, inducing the formation of giant cells, which are polykaryons. Both the proportion of polykaryons in cultures and their size (which reflects the number of nuclei per polykaryon) increase during growth in the presence of 48/80 up to 48 hr; thereafter, the cells lose viability. A predominant number of nuclei in these polykaryons contain a 4C, or higher DNA content. The data indicate that compound 48/80 impairs the cleavage (cytokinesis) and perhaps mitotic processes. Mechanisms by which compound 48/80 induces the described effects are unknown but may be related to the polycationic nature of the polymer and its interaction with the cell membrane. Certain attributes of compound 48/80 suggest that this or similar polymers may have value as research tools for the study of regulatory mechanisms involved in cell division.     

Propofol prevents lung injury after intestinal ischemia–reperfusion by inhibiting the interaction between mast cell activation and oxidative stress

Aims

Both mast cells and oxidative stress are involved in acute lung injury (ALI) induced by intestinal ischemia–reperfusion (IIR). The aim of this study was to investigate whether propofol could improve IIR-induced ALI through inhibiting their interaction.

Main methods

Repetitive, brief IIR or IIR + compound 48/80 was performed in adult Sprague–Dawley rats pretreated with saline, apocynin or propofol. And their lungs were excised for histology, ELISA and protein-expression measurements 2 h after reperfusion.

Key findings

Rats pretreated with saline developed critical ALI 2 h after IIR. We found significant elevations in lung injury scores, lung wet/dry ratio and gp91phox, p47phox, intercellular cell adhesion molecule-1 protein expressions and higher level of malondialdehyde, interleukin-6 contents, and myeloperoxidase activities, as well as significant reductions in superoxide dismutase activities, accompanied with increases in mast cell degranulation evidenced by significant increases in mast cell counts, β-hexosaminidase concentrations, and tryptase expression. And the lung injury was aggravated in the presence of compound 48/80. However, pretreated with propofol and apocynin not only ameliorated the IIR-mediated pulmonary changes beyond the biochemical changes but also reversed the changes that were aggravated by compound 48/80.

Significance

Propofol protects against IIR-mediated ALI, most likely by inhibiting the interaction between oxidative stress and mast cell degranulation.