Aspirin, protein transacetylation and inhibition of prostaglandin synthetase in the kidney.
(41/3239)
1 The effect of aspirin on the kidney has been investigated in mice and rabbits. [Acetyl-(14)C]-aspirin was administered intraperitoneally in doses ranging from subtherapeutic to toxic. The degree of acetylation of protein was determined by the radioactivity remaining on protein precipitates of renal cortex and medulla after sequential washing designed to remove non-covalently bound material. Controls were established, by the use of [carboxyl-(14)C]-aspirin.2 The acetyl-(14)C residue was bound to renal proteins in a linear manner in increasing amounts with increasing dosage up to 100 mg/kg. The [carboxyl-(14)C]-aspirin was not bound and thus the salicylate portion of the molecule was not bound covalently to the renal protein. The time course of the acetylation was rapid, consistent with the rate of aspirin absorption. The disappearance of acetylated protein was slow, with a T(1/2) of 112.5 h in the renal cortex, and 129.5 h in the renal medulla.3 Differential centrifugation, Sephadex chromatography and gel electrophoresis were carried out on tissue homogenates to determine the site of acetylation. The acetylation was greatest in the microsomal fraction, although all protein fractions showed some degree of acetylation.4 The prostaglandin synthetase activity of a particulate preparation from rabbit kidney was determined by a spectrophotometric assay of malondialdehyde formation. Aspirin (10 mg/kg, i.v.) significantly inhibited prostaglandin synthetase in the renal cortex and medulla.5 Aspirin and renal proteins undergo a transacetylation reaction resulting in stable acetylated protein, with acetylation being greatest in the microsomal fraction. Aspirin has been shown to inhibit prostaglandin synthetase and this could lead to functional impairment of the tissue. (+info)
Ketoprofen, diclofenac or ketorolac for pain after tonsillectomy in adults?
(42/3239)
We have compared the analgesic and opioid sparing effect of three i.v. non-steroidal anti-inflammatory drugs with placebo in a randomized, double-blind, placebo-controlled study in 80 adult patients after elective tonsillectomy. A standard anaesthetic was used. After induction of anaesthesia, patients received ketoprofen 100 mg, diclofenac 75 mg or ketorolac 30 mg by i.v. infusion over 30 min. Patients in the placebo group received saline. Ketoprofen and diclofenac infusions were repeated after 12 h and ketorolac infusion at 6 h and 12 h. Oxycodone was used as rescue analgesic. Patients in the ketoprofen group requested 32% less opioid and patients in the diclofenac and ketorolac groups 42% less opioid than those in the placebo group (P < 0.05). There were one, two and six patients in the placebo, diclofenac and ketorolac groups, respectively, but none in the ketoprofen group, who did not request opioid analgesia during the study (P < 0.05, ketorolac vs placebo and ketoprofen). Visual analogue pain scores were similar in all groups. Visual analogue satisfaction scores were significantly higher in the diclofenac group compared with the placebo group. The incidence of nausea was 44-54%. There were no differences in the incidence of other adverse reactions. We conclude that all three non-steroidal anti-inflammatory drugs were superior to placebo after tonsillectomy. (+info)
Pentobarbital-sensitive EDHF comediates ACh-induced arteriolar dilation in the hamster microcirculation.
(43/3239)
It is unclear to what extent the endothelium-derived hyperpolarizing factor (EDHF) contributes to the control of microcirculatory blood flow in vivo. We analyzed, by intravital microscopy in hamster muscles, the potential role of EDHF along the vascular tree under stimulated (ACh) or basal conditions. Experiments were performed in conscious as well as anesthetized (pentobarbital, urethan) animals. Additionally, cellular effects of the potential EDHF were studied in isolated small arteries. In pentobarbital-anesthetized animals, treatment with Nomega-nitro-L-arginine (L-NNA; 30 micromol/l) and indomethacin (3 micromol/l) reduced the dilation in response to 10 micromol/l ACh from 60 +/- 6 to 20 +/- 4%. This nitric oxide/prostaglandin-independent dilation (NPID), which was of a similar magnitude in large and small arterioles, was abolished by potassium depolarization or charybdotoxin (ChTX, 1 micromol/l) but not by glibenclamide. In conscious animals, NPID amounted to 33 +/- 3%. The inhibitor of the P-450 monooxygenase 17-octadecynoic acid (ODYA) reduced NPID further to 9 +/- 4%. ChTX abolished the NPID and also reduced basal diameters (by -11 +/- 3%). The induction of anesthesia with pentobarbital reduced NPID (to 12 +/- 6%), whereas urethan anesthesia was without effect. Pentobarbital also reduced the ACh-induced hyperpolarization of vascular smooth muscle in isolated arteries, whereas ChTX abolished it. This study suggests that a considerable part of the ACh dilation in the microcirculation is mediated by EDHF, which also contributes to the control of basal tone in conscious animals. The direct inhibitory effect of pentobarbital and ODYA supports the idea that "microcirculatory" EDHF is a product of the cytochrome P-450 pathway. The role of EDHF might be underestimated in pentobarbital-anesthetized animals. (+info)
Altered reflex control of cutaneous circulation by female sex steroids is independent of prostaglandins.
(44/3239)
We tested the hypothesis that the shift in the cutaneous vasodilator response to hyperthermia seen with elevated female reproductive hormones is a prostaglandin-dependent resetting of thermoregulation to higher internal temperatures, similar to that seen in the febrile response to bacterial infection. Using water-perfused suits to control body temperature, we conducted heat stress experiments in resting women under conditions of low and high progesterone and estrogen and repeated these experiments after an acute dose of ibuprofen (800 mg). In six women the hormones were exogenous (oral contraceptives); three women had regular menstrual cycles and were tested in the early follicular and midluteal phases. Resting oral temperature (Tor) was significantly elevated with high hormone status (P < 0.05); this was not affected by ibuprofen treatment (P > 0.2). The Tor threshold for cutaneous vasodilation was significantly increased by high hormone status (+0.27 +/- 0.07 degrees C, P < 0. 02); the shift was not affected by ibuprofen treatment (with ibuprofen: +0.29 +/- 0.08 degrees C, P > 0.2 vs. control experiments). The Tor threshold for sweating was similarly increased by high hormone status (+0.22 +/- 0.05 degrees C, P < 0.05); this shift was not influenced by ibuprofen (with ibuprofen: +0.35 +/- 0. 05, P > 0.1 vs. control experiments). Thus the shift in thermoregulatory control of skin blood flow and sweating mediated by female reproductive steroids is not sensitive to ibuprofen; it therefore appears that this shift is independent of prostaglandins. (+info)
Distinct roles of prostaglandin H synthases 1 and 2 in T-cell development.
(45/3239)
Prostaglandin G and H synthases, or cyclooxygenases (COXs), catalyze the formation of prostaglandins (PGs). Whereas COX-1 is diffusely expressed in lymphoid cells in embryonic day 15.5 thymus, COX-2 expression is sparse, apparently limited to stromal cells. By contrast, COX-2 is predominant in a subset of medullary stromal cells in three- to five-week-old mice. The isozymes also differ in their contributions to lymphocyte development. Thus, experiments with selective COX-1 inhibitors in thymic lobes from normal and recombinase-activating gene-1 knockout mice support a role for this isoform in the transition from CD4(-)CD8(-) double-negative (DN) to CD4(+)CD8(+) double-positive (DP). Concordant data were obtained in COX-1 knockouts. Pharmacological inhibition and genetic deletion of COX-2, by contrast, support its role during early thymocyte proliferation and differentiation and, later, during maturation of the CD4 helper T-cell lineage. PGE2, but not other PGs, can rescue the effects of inhibition of either isoform, although it acts through distinct EP receptor subtypes. COX-dependent PG generation may represent a mechanism of thymic stromal support for T-cell development. (+info)
Isoprostanes and PGE2 production in human isolated pulmonary artery smooth muscle cells: concomitant and differential release.
(46/3239)
The isoprostanes are a group of biologically active arachidonic acid metabolites initially thought to be formed under conditions of oxidative stress and independently of cyclooxygenase. However, recent studies have demonstrated isoprostane production under conditions in which cyclooxygenase is intentionally activated/induced. Here we describe for the first time formation of isoprostanes by human vascular cells via independent pathways of oxidative stress and cyclooxygenase induction. We compared the release of the isoprostane with that of the traditional prostaglandin, prostaglandin E2. Cyclooxygenase-2 induction was confirmed by Western blot. When cells were stimulated with cytokines, the release of isoprostanes was inhibited by the cyclooxygenase-1 and -2 inhibitor indomethacin as well by as the cyclooxygenase-2 selective inhibitor L-745,337. However, treatment of cells with the superoxide-producing enzyme xanthine oxidase also resulted in isoprostane release, which was not affected by cyclooxygenase inhibition, unlike PGE2 release under the same condition. Thus, two independent pathways relating to oxidative stress and cyclooxygenase-2 induction form isoprostanes. These findings may have particular importance in diseases such as sepsis and ARDS in which oxidant stress occurs and cyclooxygenase is induced. (+info)
Role of interleukin 1 in the regulation of cyclooxygenase gene expression in rat endometrial stromal cells.
(47/3239)
Interleukin 1 alpha (IL-1 alpha) stimulates prostaglandin production and cyclooxygenase activity in endometrial stromal cells isolated from the uteri of ovariectomized rats that have been sensitized for the decidual cell reaction. The aim of the present study was to examine the effect of IL-1 alpha on the amount of cyclooxygenase mRNA and protein in these cells. Treatment with IL-1 alpha (20 ng ml-1) for 24 h significantly increased steady-state concentrations of cyclooxygenase 2 (COX-2) mRNA and protein in the cells, as determined by northern and western blot analyses, respectively. Cyclooxygenase 1 (COX-1) mRNA and protein were not detected. Dexamethasone (5 mumol l-1) prevented the IL-1 alpha-induced increase in COX-2 steady-state mRNA. Immunocytochemical staining of COX-2 in the treated cells indicated that IL-1 alpha increased staining, while dexamethasone inhibited this increase. Furthermore, the changes in staining were generalized and not confined to a small subpopulation of cells. These data demonstrate that IL-1 alpha increases steady-state concentrations of COX-2 mRNA and protein in endometrial stromal cells isolated from the uteri of rats that have been sensitized for decidualization. (+info)
Inhibitory effects of caffeic acid phenethyl ester on the activity and expression of cyclooxygenase-2 in human oral epithelial cells and in a rat model of inflammation.
(48/3239)
We investigated the mechanisms by which caffeic acid phenethyl ester (CAPE), a phenolic antioxidant, inhibited the stimulation of prostaglandin (PG) synthesis in cultured human oral epithelial cells and in an animal model of acute inflammation. Treatment of cells with CAPE (2.5 microg/ml) suppressed phorbol ester (12-O-tetradecanoylphorbol-13-acetate; TPA) and calcium ionophore (A23187)-mediated induction of PGE2 synthesis. This relatively low concentration of CAPE did not affect amounts of cyclooxygenase (COX) enzymes. CAPE nonselectively inhibited the activities of baculovirus-expressed hCOX-1 and hCOX-2 enzymes. TPA- and A23187-stimulated release of arachidonic acid from membrane phospholipids was also suppressed by CAPE (4-8 microg/ml). Higher concentrations of CAPE (10-20 microg/ml) suppressed the induction of COX-2 mRNA and protein mediated by TPA. Transient transfections using human COX-2 promoter deletion constructs were performed; the effects of TPA and CAPE were localized to a 124-bp region of the COX-2 promoter. In the rat carrageenan air pouch model of inflammation, CAPE (10-100 mg/kg) caused dose-dependent suppression of PG synthesis. Amounts of COX-2 in the pouch were markedly suppressed by 100 mg/kg CAPE but were unaffected by indomethacin. These data are important for understanding the anticancer and anti-inflammatory properties of CAPE. (+info)