Cyclic stretch reduces myofibrillar protein synthesis despite increases in FAK and anabolic signalling in L6 cells.

Muscle protein synthesis is increased after exercise, but evidence is now accruing that during muscular activity it is suppressed. In life, muscles are subjected to shortening forces due to contraction, but may also be subject to stretching forces during lengthening. It would be biologically inefficient if contraction and stretch have different effects on muscle protein turnover, but little is known about the metabolic effects of stretch. To investigate this, we assessed myofibrillar and sarcoplasmic protein synthesis (MPS, SPS, respectively) by incorporation of [1-13C]proline (using gas chromatography-mass spectrometry) and anabolic signalling (by phospho-immunoblotting and kinase assays) in cultured L6 skeletal muscle cells during 30 min of cyclic stretch and over 30 min intervals for up to 120 min afterwards. SPS was unaffected, whereas MPS was suppressed by 40 +/- 0.03% during stretch, before returning to basal rates by 90-20 min afterwards. Paradoxically, stretch stimulated anabolic signalling with peak values after 2-30 min: e.g. focal adhesion kinase (FAK Tyr576/577; +28 +/- 6%), protein kinase B activity (Akt; +113 +/- 31%), p70S6K1 (ribosomal S6 kinase Thr389; 25 +/- 5%), 4E binding protein 1 (4EBP1 Thr37/46; 14 +/- 3%), eukaryotic elongation factor 2 (eEF2 Thr56; -47 +/- 4%), extracellular regulated protein kinase 1/2 (ERK1/2 Tyr202/204; +65% +/- 9%), eukaryotic initiation factor 2alpha (eIF2alpha Ser51; -20 +/- 5%, P < 0.05) and eukaryotic initiation factor 4E (eIF4E Ser209; +33 +/- 10%, P < 0.05). After stretch, except for Akt activity, stimulatory phosphorylations were sustained: e.g. FAK (+26 +/- 11%) for > or =30 min, eEF2 for > or =60 min (peak -45 +/- 4%), 4EBP1 for > or =90 min (+33 +/- 5%), and p70S6K1 remained elevated throughout (peak +64 +/- 7%). Adenosine monophosphate-activated protein kinase (AMPK) phosphorylation was unchanged throughout. We report for the first time that acute cyclic stretch specifically suppresses MPS, despite increases in activity/phosphorylation of elements thought to increase anabolism.

Stability of ascorbic acid and uptake of the vitamin by embryonic chick femurs during long-term culture.

Ascorbic acid was added to organ cultures of 15-day-old embryonic chick femurs. The ascorbate that was taken up into the cultured tissue reached maximal concentrations after 1.5 h. The half-life of tissue ascorbate was 12-24 h, whereas the half-life of medium ascorbate was 1-2 h. 24 h after supplementing with ascorbate, the tissue concentrations were still 30-60-fold higher than the medium concentrations at that time. If no ascorbate was added to the culture medium, the tissue concentration declined over a period of days: after 6 days 2-7% of the pre-culture tissue concentrations were still present. Embryonic chick femurs in vitro are therefore shielded from massive fluctuations in the concentration of ascorbic acid in the medium, resulting from intermittent supplementation. Hence, feeding a culture with the vitamin once every 24 h is sufficient to ensure adequate levels in the tissue.

Ascorbic acid requirements for collagen synthesis (proline hydroxylation) during long-term culture of embryonic chick femurs.

Although ascorbate is essential for collagen synthesis, especially the hydroxylation of prolyl residues, femurs from 15-day-old chick embryos could be cultured for at least 5 days without ascorbate additions to the medium before the hydroxylation of proline was significantly impaired. Only when the ascorbate concentration in the tissue was less than 6 micrograms/g wet weight (compared with 50-70 micrograms/g wet weight in fresh tissue), was hydroxyproline formation reduced by 75-85%. When sufficient ascorbate was present in the culture medium, the femurs accumulated and stored the vitamin at concentrations which were 5-10-fold above the threshold required for collagen synthesis. This may represent an adaptive mechanism to the instability of the vitamin. Above the minimum required level, synthesis of collagen was not quantitatively related to ascorbate concentration. To obtain comprehensive data on changes in collagen content and collagen synthesis during culture, total hydroxyproline was measured as well as [3H]proline uptake and the formation of [3H]hydroxyproline. These three parameters were assessed with a new combined assay, which was modified from existing methods, yet was more sensitive and less tedious.

Effect of polyunsaturated fatty acids of the n-3 and n-6 series on lipid composition and eicosanoid synthesis of platelets and aorta and on immunological induction of atherosclerosis in rabbits.

The effect of dietary fish oil (rich in n-3 polyunsaturated fatty acids (PUFA], corn oil (rich in n-6 PUFA) and coconut oil (low in n-3 and n-6 PUFA) on the induction of atherosclerosis by serum sickness in rabbits was investigated over a 12-month period. Dietary fish oil led to a significant increase in the level of eicosapentaenoic acid (EPA) in all platelet phospholipid fractions and to a significant reduction in the level of platelet phosphatidylethanolamine arachidonic acid (AA). In aortic total phospholipids, rabbits given fish oil showed a significant reduction in AA and a significant increase in EPA. Rabbits given fish oil showed significantly lower collagen-induced platelet thromboxane A2 release and aortic production of 6-keto-PGF1 alpha. Serum total immune complex levels and anti-horse serum IgG levels were not influenced by diet. There was a significant reduction in total aortic atherosclerosis in fish oil-fed animals compared with coconut oil fed animals.

Effect of sucralfate and cimetidine on rheumatoid patients with active gastroduodenal lesions who are taking nonsteroidal anti-inflammatory drugs. A pilot study.

In a pilot study, 26 rheumatoid arthritic patients taking continuous, stable dosage regimens of nonsteroidal anti-inflammatory drugs and with developed gastric and duodenal lesions were administered sucralfate 1 g four times per day (14 patients) or cimetidine 400 mg twice daily (12 patients) in a single-blind regimen for six weeks. Eleven of the patients given sucralfate and eight of the patients taking cimetidine had improved lesion scores. The lesion score of 10 of the 14 patients taking sucralfate and four of the 12 patients taking cimetidine improved by 50 percent or better (not significant). The antrum and body of the gastric mucosa and the mucosa of the duodenum synthesized prostanoids and thromboxane A2, and there was no significant difference in the synthesis of individual prostanoids at entry to the trial in the groups assigned to sucralfate or cimetidine. After six weeks of administration of sucralfate, prostaglandin E2 (PGE2) synthesis by the antrum and body, but not the duodenum, was significantly greater than observed in the biopsy specimens at entry despite continuation of non-steroidal anti-inflammatory drug therapy. After six weeks of cimetidine treatment, no change in PGE2 synthesis was noted in any biopsy specimens when compared with the synthesis at entry. No change in the synthesis of PGF2 alpha, 6-oxo-PGF1 alpha, or thromboxane B2 was noted in gastric or duodenal biopsy specimens in any treatment group. Sucralfate and cimetidine administration resulted in improved gastroduodenal lesion scores in rheumatoid arthritic patients continuing with nonsteroidal anti-inflammatory drug therapy.

Regulation of noradrenaline overflow in rat cerebral cortex by prostaglandin E2.

1 The effects of prostaglandin E2 (PGE2), PGF2 alpha and PGI2 and of inhibitors of prostaglandin synthesis and action, on the K+-evoked [3H]-noradrenaline ([3H]-NA) overflow from rat cerebral cortex slices have been investigated. 2 PGE2 reduced, while indomethacin (a prostaglandin synthesis inhibitor) or SC 19220 (a prostaglandin receptor antagonist) increased, the evoked overflow compared with controls. 3 The inhibition of [3H]-NA overflow by PGE2 was dose-dependently antagonized by SC 19220. 4 The results indicate that PGE2 modulates NA release in rat cerebral cortex in vitro.

Characterization of the 5-hydroxytryptamine receptor type involved in inhibition of spontaneous activity of human isolated colonic circular muscle.

1. Experiments were carried out to characterize pharmacologically the 5-hydroxytryptamine (5-HT) receptor types which mediate inhibition of spontaneous contractions of the intertaenial circular muscle in human isolated colon. 2. 5-HT caused a reproducible concentration-dependent inhibition of spontaneous contractions of the circular muscle of human colon in vitro with a mean EC50 value of 0.2 microM and 95% confidence limits of 0.1-0.5 microM. No evidence for a contractile action of 5-HT was found. Tetrodotoxin (TTX, 1.5 microM) caused a rightward shift of the concentration-response curve of 5-HT with a concentration-ratio of 2.9. 3. The inhibitory response to 5-HT was mimicked by several indoles with the rank order of potency 5-HT > 5-methoxytryptamine = alpha-methyl-5-HT > 5-carboxamidotryptamine >> 2-methyl-5-HT. 5-Hydroxyindalpine was inactive. 4. The substituted benzamides were agonists with the following rank order of potency, 5-HT > renzapride > zacopride > metoclopramide > cisapride. 5. The inhibitory responses to 5-HT were not inhibited by methysergide (10 microM) or methiothepin (1 microM), which are antagonists selective for 5-HT1-like and 5-HT2 receptors, nor by ondansetron (10 microM) which is an antagonist at 5-HT3 receptors. 6. The inhibitory responses induced by 5-HT and 5-methoxytryptamine were competitively antagonized by a weak 5-HT4 receptor antagonist, tropisetron, with pKB values of approximately 6. Tropisetron had no significant effect on the inhibitory response curve produced by isoprenaline (0.01-100 microM). 7. The pharmacological profile of the 5-HT-evoked relaxations of human colon circular muscle are consistent with activation of a 5-HT4-like receptor.

Investigation of the effects of platelet-activating factor (PAF) on ion transport and prostaglandin synthesis in human colonic mucosa in vitro.

1 We have investigated the effects of platelet-activating factor (PAF), an endogenous mediator of inflammation, on ion transport and prostaglandin synthesis in the human isolated colon. 2 Application of PAF to the serosal surface of human colonic mucosa induced a marked, concentration-dependent increase in ion transport. Mucosal application was without effect. 3 The secretory response to PAF was significantly inhibited by prior application of a specific PAF receptor antagonist WEB 2170, indicating that the response is dependent on PAF receptor activation. 4 The response to PAF was attenuated by prior application of indomethacin or piroxicam, implicating products of the cyclo-oxygenase pathway in the response. 5 The response to PAF was attenuated by the loop diuretic bumetanide, indicating an involvement of chloride ion secretion in the response. 6 Addition of PAF to the serosal surface induced a significant increase in serosal prostaglandin E2 (PGE2), but not 6-oxo-PGF1alpha release. There was no effect on mucosal application of PAF. 7 In summary, we have shown that PAF is a potent secretagogue in isolated preparations of human colon and that the response is dependent on a specific PAF receptor, cyclo-oxygenase products and bumetanide-sensitive chloride ion transport.

Differences in response to 5-HT4 receptor agonists and antagonists of the 5-HT4-like receptor in human colon circular smooth muscle.

1. In isolated circular smooth muscle strips of human colon 5-hydroxytryptamine (5-HT) produced a concentration-related inhibition of spontaneous motility. 2. The azabicycloalkyl benzimidazolones, BIMU 8 and BIMU 1, which have 5-HT4 receptor stimulant properties, inhibited motility with EC50 values of 0.76 microM and 3.19 microM respectively and their Emax values were not significantly different from 5-HT (EC50, 0.13 microM). 3. The 5-HT4 receptor antagonist, DAU 6285 (1-10 microM), displaced the 5-HT concentration-response curve to the right in a parallel concentration-dependent manner without depressing the maximum. The Schild plot was linear and the slope did not differ significantly from unity giving a pA2 value of 6.32. 4. The high affinity selective 5-HT4 receptor antagonist, GR 113808, at a concentration of 3 nM displaced the 5-HT concentration-response curve in a parallel manner giving an apparent pKB estimate of 8.9 +/- 0.24. However, higher concentrations of 10-100 nM GR 113808 did not result in a further significant displacement of the 5-HT concentration-response curve and there was no suppression of Emax. 5. GR 113808 (10 nM) also caused a parallel displacement of the concentration-response curve to the 5-HT4 receptor agonist, 5-methoxytryptamine (5-MeOT) giving apparent pKB values ranging from 8.3-9.3. 6. GR 113808 (3-100 nM) failed to displace 5-HT or 5-MeOT concentration-response curves in tissue strips from 3 patients out of a total of 10 patients studied in whom the response to 5-HT and 5-MeOT was normal. 7. The 5-HT4 receptor antagonist, SDZ 205-557 (0.3-10 microM), had no significant effect on 5-HT-induced inhibition of spontaneous motility.8. The present results are discussed in the light of variability of response to GR 113808 and SDZ205-557 in other tissues.9. Overall, our data indicate that human colon circular smooth muscle can be regarded as a site in which 5-HT4-like receptors are present but it is as yet unclear whether these results are also an indication of receptor variation.

Characterization of muscarinic receptors mediating contractions of circular and longitudinal muscle of human isolated colon.

1. The effects of seven muscarinic receptor antagonists were used to characterize the receptors which mediate carbachol-evoked contractions of intertaenial circular and taenial longitudinal muscle in human isolated colon. The effects of these antagonists were studied upon colon contractions induced by cumulatively added carbachol which had mean EC50 values of 11.7 +/- 2.3 microM (n = 8) and 12.6 +/- 2.3 microM (n = 8) respectively upon circular and longitudinal smooth muscle. 2. All antagonists displaced concentration-response curves to carbachol to the right in a parallel manner. The maximum concentration of each antagonist added (30 nM-10 microM) did not significantly suppress the maximum response. 3. In circular muscle, the M3 muscarinic receptor antagonists, 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP), hexahydrosiladiphenidol (HHSiD) and para-fluoro-hexahydrosiladiphenidol (p-F-HHSiD) inhibited responses with pA2 values of 9.41 +/- 0.23, 7.17 +/- 0.07, 6.94 +/- 0.18 respectively. The M2 muscarinic receptor antagonist, AF-DX 116, the M2/M4 muscarinic receptor antagonist, himbacine, and the M1 muscarinic receptor antagonist, pirenzepine, yielded pA2 values of 7.36 +/- 0.43, 7.47 +/- 0.14 and 7.23 +/- 0.48 respectively. The non-selective antagonist, atropine, had a pA2 of 8.72 +/- 0.28. 4. In longitudinal muscle 4-DAMP, HHSiD, p-F-HHSiD, AF-DX 116, himbacine and pirenzepine gave pA2 values of 9.09 +/- 0.16, 7.45 +/- 0.43, 7.44 +/- 0.21, 6.44 +/- 0.1, 7.54 +/- 0.40, 6.87 +/- 0.38 respectively. Atropine yielded a pA2 value of 8.60 +/- 0.08. 5. The pharmacological profile of antagonist affinities at the muscarinic receptor population responding to muscarinic agonist-evoked contraction is similar to that widely accepted as characterizing the activation of an M3 muscarinic receptor subtype, although pA2 values of some antagonists are lower than that seen in other investigations.

Ulcerative colitis: effect of sulphasalazine, its metabolites and indomethacin on the ability of human colonic mucosa to metabolize prostaglandins in vitro.

1 Homogenates of mucosa from human colon metabolize [3H]-prostaglandin E1 in the presence of nicotinamide adenine dinucleotide to 15-oxo prostaglandin E1 or 15-oxo, 13,14 dihydro prostaglandin E1. 2 Metabolic capacity of tissue from patients with active ulcerative colitis under treatment with sulphasalazine (0.021 +/- 0.004 nmol/Mg protein +/- s.e. mean) did not differ from mucosa of normal patients (0.02 +/- 0.004 nmol/mg protein) during 1 h incubation. 3 Sulphasalazine inhibits prostaglandin E1 metabolism by mucosal homogenates in a dose-dependent manner with an ID50 of 125 microM. Its therapeutically active metabolite, 5-aminosalicylic acid (2.6 mM) was without significant inhibitory activity. 4 Indomethacin inhibits prostaglandin E1 metabolism by colonic mucosa with an ID50 of 388 microM. 5 At present we cannot clearly relate the therapeutic benefit of sulphasalazine and its therapeutically active metabolite, 5-aminosalicylic acid, in ulcerative colitis to their effects on prostaglandin E synthesis or metabolism in vitro.

Collagen solubility and tensile properties of the rat uterine cervix in late pregnancy: effects of arachidonic acid and prostaglandin F 2 alpha.

The collagen concentration in rat uterine cervix was less on day 18 of pregnancy than in the non-pregnant animal but did not diminish further as pregnancy proceeded. The solubility of cervical collagen in warm acetic acid (0.5 mol/l) was increased on day 22 compared with days 19, 20 and 21 of pregnancy, and there was a positive correlation of increasing solubility with the tissue rate of creep (a measure of reducing stiffness of the cervix). Treatment of rats subcutaneously with arachidonic acid or prostaglandin F 2 alpha (PGF 2 alpha) on day 18 of pregnancy decreased the stiffness of the tissue when assessed on day 19 and this was accompanied by increased solubility in cold saline (0.45 mol/1), cold acetic acid and warm acetic acid and a reduction in collagen concentration. These results suggest that collagen properties rather than concentration are important in determining the stiffness of the rat uterine cervix at term and that exogenous PGF 2 alpha and arachidonic acid cause biochemical changes in collagen structure unlike those seen at term in untreated animals.

Production of prostaglandins E and Falpha by corpora lutea, corpora albicantes and stroma from the human ovary.

This study has shown that corpora lutea, stromal tissue and corpora albicantes from human ovaries contain prostaglandin E (PGE) and PGFalpha, and that the two former tissues can synthesize these prostaglandins during incubation. Enhanced syntheses, especially of PGE, occurred on adding arachidonic acid to the incubation medium, and the presence of prostaglandin synthetase activity was conclusively demonstrated. In corpora lutea obtained during the early and mid-luteal phase, the mean concentrations of PGE and PGFalpha were 34.3 and 9l9 ng/g respectively (mean ratio PGE:PGFalpha = 3.7); similar values were found in three corpora lutea from women at 10-12 weeks of pregnancy. All these corpora lutea contained appreciable amounts of progesterone and oestradiol-17beta. Prostaglandin levels were generally lower in corpora lutea obtained during the late luteal phase, although the PGE:PGFalpha ratio had increased to a mean value of 8.4. In corpora albicantes, the concentrations of both PGE and PGFalpha were significantly higher than the levels found in corpora lutea (P less than 0.01), whilst the mean ratio of PGE:PGFalpha had fallen significantly to 1.8 (P less than 0.01). Prostaglandin levels in stromal tissue varied considerably between individuals. The mean values were significantly lower than those of the corpora albicantes (P less than 0.01) but not significantly different to corpora lutea at any stage. These findings are discussed in relation to the possible role of prostaglandins in ovarian steroidogenesis and corpus luteum regression in man.

Prostaglandins: pharmacology and clinical application.

PIP: Prostaglandin research has been 1 of the most stimulating features of biomedical investigation in the past decade. Interest developed at a time of expanding knowledge of hormonal and neurohormonal behavior and research work received a tremendous impetus in the early 1960s with the elucidation in Sweden of the chemical structures of prostaglandins, followed by the discovery of their biosynthetic pathways. The original findings of large amounts of prostaglandin in the male accessory genital glands and their secretions, and subsequent discovery in the menstrual and amniotic fluids linked these substances with human production. As a result of further investigation, clinical applications of prostaglandins for the induction of labor and termination of early unwanted pregnancies have been developed. Apart from the functions of the prostaglandins in the reproductive area, they have been shown to have a widespread distribution in the body and produce many different pharmacological effects. Prostaglandins are thought to be involved in the regulation of blood pressure and through their vascular effects have therapeutic potential in the treatment of hypertension and peripheral vascular disease. Through their bronchodilator effect, some prostaglandins may become useful in the treatment of asthma.^ieng

Catabolism of platelet-activating factor by human colonic mucosa. Calcium dependence of the catabolizing enzymes.

The catabolism of platelet-activating factor (PAF) and lyso PAF by a supernatant fraction of human colon mucosa homogenates has been studied in vitro. PAF is initially catabolized to lyso PAF by mucosal enzymes via removal of its acetyl group. Incubates in Ca(2+)-free Tris with EDTA showed that the acetyl hydrolase was Ca2+ independent. Addition of the hydrolase inhibitor, phenyl methyl sulphonyl fluoride, significantly reduced the catabolism of PAF. Lyso PAF was further catabolized in at least two ways. An acyl group was incorporated into the sn-2 position of lyso PAF to give 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine (alkyl acyl GPC); this step was Ca2+ independent as shown by omitting Ca2+ and adding EDTA to the incubate. Formation of alkyl acyl GPC was confirmed by HPLC. Alternatively, choline was removed from the head group of lyso PAF by a calcium-dependent lyso phospholipase D. Under the experimental conditions utilized a neutral lipid product was formed but significant amounts of the intermediate lysophosphatidic acid could not be detected. A substance with a chromatographic mobility of Rf = 0.8 on TLC plates having an intact phosphorylcholine head group was also formed but has not yet been identified. It is concluded that the human colon mucosa contains enzymes that actively catabolize pro-inflammatory PAF and lyso PAF.

Compartmentalisation and characteristics of a Ca2+-dependent phospholipase A2 in human colon mucosa.

The biochemical properties of the phospholipase A2 (PLA2) found in the 100,000 x g centrifugate cytosol or particulate fractions of human colonic mucosa have been investigated using both deoxycholate-solubilized and Escherichia coli (E. coli) phospholipids as substrates. PLA2 activity was present in both subcellular fractions and the profiles of biochemical activites were similar. Activity in the particulate fraction was approximately twofold greater than the cytosol fraction when expressed on the basis of protein concentration. The PLA2 is Ca2+ dependent and using EGTA-regulated buffers cytosolic or particulate fraction activity was similar at both 10 microm or 10 mm Ca2+ concentrations. Using deoxycholate-phospholipid micelles as substrate a small but statistically significant twofold preference for glycero-phosphatidylcholine bearing sn-2-arachidonate compared with sn-2-oleate was seen, but this preference was not noted using arachidonate or oleate labelled E. coli membranes. Dithiothreitol (10 mM) reduced colon mucosal cytosol PLA2 activity significantly by 63.5 +/- 1.90% in cytosol and by 30.54 +/- 1.27% in microsomes using micelles as substrate or by 84.3 +/- 2.30% in cytosol and by 69.33 +/- 11.30% in microsomes using oleate-labelled E. coli as substrates. Warming at 57 degrees C reduced activity significantly by 35.0 +/- 5.80% in microsomes and by 40.0 +/- 7.08% in cytosol. Acid treatment increased PLA2 activity to 148 +/- 16.3% in microsomes and 145 +/- 18.6% in cytosol. When mucosal preparations were subjected to heparin-Sepharose chromatography, it bound tightly and eluted in the same position on a salt gradient as authentic human group II PLA2. Further purification by gel-permeation chromatography gave activity in the 14 kDa region of the elution profile. These features have many of the characteristics expected of a 14 kDa isoform of PLA2 but exhibit activity at concentrations of Ca2+ that are relevant in the intracellular environment and may participate in cellular lipid metabolism.

Cardiovascular actions of prostaglandin Fa-alpha infusion in man.

PIP: The effect of prostaglandin F2alpha on the cardiovascular system in 5 healthy male volunteers and 1 female volunteer between the ages of 18 and 31 years was investigated by intravenous infusion of 0.01-2.0 mug/kg/min. There was no effect on the systolic and diastolic blood pressures, heart rate, electrocardiogram or the respiration rate. Similarly rapid single intravenous injections of 1-40 mug of prostaglandin F2alpha failed to alter any of these parameters. 1 volunteer was infused with 0.2 mug/kg/min of prostaglandin E1 for 30 minutes and this resulted in an increase in heart rate and a fall in both systolic and diastolic pressures. Recently, prostaglandin F2alpha has been used for the induction of labor in 10 women at or near term.^ieng

The role of nitric oxide in mediating non-adrenergic non-cholinergic relaxation in longitudinal muscle of human taenia coli.

Electrical field stimulation (EFS) of isolated longitudinal muscle of human taenia coli at 4Hz produced relaxation which was abolished by tetrodotoxin but not adrenergic and cholinergic blockade (NANC-relaxation). NG-nitro L-arginine (L-NOARG; 1-100 microM), an NO synthesis inhibitor, produced a concentration-dependent partial inhibition of the NANC response; 10 microM L-NOARG inhibited EFS-induced relaxation by 48.6 +/- 5.20% and 100 microM L-NOARG by 54.2 +/- 10.1%. L-Arginine (1mM), but not D-arginine (1mM) partially reversed the inhibitory effect and this was inversely proportional to the concentration of L-NOARG used. Cumulative administration of NO (acidified sodium nitrite solution; 1-100 microM) produced a concentration-dependent relaxation of the strips. L-NOARG (1 mM) did not affect either NO or isoprenaline-induced relaxations. These results provide the first preliminary evidence that NO is partially responsible for the NANC inhibitory transmission in the longitudinal muscle of the taenia coli of human colon.

Inflammatory bowel disease: the in vitro effect of sulphasalazine and other agents on prostaglandin synthesis by human rectal mucosa.

1. Prostaglandin (PG) E2 and F2 alpha synthesis in vitro by human rectal mucosa was significantly greater in patients with Inflammatory Bowel Disease (IBD) than in controls. 2. The addition of 250 microM sulphasalazine (SASP) significantly increased synthesis by rectal mucosa from patients with IBD, (ulcerative colitis and Crohn's disease) and controls after 1 h of incubation in Krebs' solution at 37 degrees C. 3. Flurbiprofen, indomethacin, sodium salicylate and 5-aminosalicylic acid decreased PGE2 and F2 alpha synthesis. 4. Sodium carbenoxolone decreased PGF2 alpha synthesis but had no effect on PGE2. Disodium cromoglycate, sulphapyridine, salicylazosulphadimidine and methylsulphasalazine had no effect on PG synthesis. 5. The data show marked variations in effect on PG synthesis in vitro of substances that have been investigated clinically for their actions on IBD.

The effect of sulphasalazine on the in vitro activation of human peripheral blood mononuclear cells by phytohemagglutinin P.

The in vitro action of sulphasalazine, BW 755-C and indomethacin on phytohemagglutinin P-induced human peripheral blood mononuclear cell activation was studied. Sulphasalazine increased, while indomethacin and BW 755-C decreased, prostaglandin E2 (PGE2) accumulation in activated cultures. When used together with indomethacin or BW 755-C, sulphasalazine did not counteract the inhibition of PGE2 caused by the other two. Sulphasalazine inhibited phytohemagglutinin P-induced cell activation in a concentration-dependent manner even when used together with indomethacin or BW 755-C. BW 755-C inhibited cell activation at 350 microM, whereas at 11 microM it only increased sulphasalazine-induced inhibition. The implications of these findings on the etiopathology of inflammatory bowel disease are discussed.