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P V Halushka

Publications and source records attributed to P V Halushka.

At least 19 recordsLinked to original sources
PubMed1992

Characterization of rat glomerular thromboxane A2 receptors: comparison to rat platelets.

This study was designed to characterize rat glomerular thromboxane A2 (TxA2) receptors and compare them to rat platelet TxA2 receptors. The radioligand binding characteristics of the receptors were characterized using [125I][1S-(1 alpha,2 beta(5Z),3 alpha-(1E,3R*),4 alpha]-7-[3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl)-7-oxabicyclo- [2.2.1]heptan-2yl]-5-heptenoic acid ([125I]BOP), a TxA2 agonist. Equilibrium binding with [125I]BOP, as well as competitive binding assays between [125I]BOP and 13-azapinane TxA2 receptors antagonists, were performed in rat glomerular membranes (RGM) and washed rat platelets (WRP). [125I]BOP identified a single class of TxA2 receptor sites in glomerular membranes with a Kd of 318 +/- 55 pM and a Bmax of 260 +/- 62 fmol/mg protein (n = 14). [125I]BOP was displaced by the TxA2 agonist 15S-hydroxy-11 alpha,9 alpha(epoxymethano)-prosta-5Z,13E-dienoic acid (U-46,619) (IC50 = 22 +/- 6 nM, n = 3), the antagonist SQ-29,548 (IC50 = 41 +/- 7 nM, n = 4), and stereoselectively by the antagonists (-)-9-chlorobenzyl-6-fluoro-1,2,3,4-tetrahydrocarbazol-1-yl acetic acid (L-657,925) (IC50 = 0.27 +/- 0.04 nM, n = 3) and (+)-9-chlorobenzyl-6-fluoro-1,2,3,4-tetrahydrocarbazol-1-yl acetic acid (L-657,926) (IC50 = 124 +/- 0 nM, n = 2). The ability of six 13-azapinane TxA2 antagonists to compete with [125I]BOP was evaluated. The rank orders for the 13-azapinanes showed no significant correlation between RGM and WRP.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Endotoxin tolerance is associated with altered GTP-binding protein function.

Previous studies have suggested that guanine nucleotide regulatory (G) proteins modulate endotoxin-stimulated peritoneal macrophage arachidonic acid (AA) metabolism. Endotoxin-stimulated metabolism of AA by peritoneal macrophages is decreased in endotoxin tolerance (Rogers et al. Prostaglandins 31: 639-650, 1986). These observations led to a study of G protein function and AA metabolism by peritoneal macrophages in endotoxin tolerance. Endotoxin tolerance was induced by the administration of sublethal doses of endotoxin. AA metabolism was assessed by measurement of thromboxane B2 (TxB2), a cyclooxygenase metabolite. NaF (5 mM), an activator of G proteins, significantly stimulated TxB2 synthesis in control macrophages from 7.7 +/- 0.2 to 19.1 +/- 0.6 (SE) ng/ml (P less than 0.05) at 2 h and was partially inhibited by pertussis toxin, suggesting a G protein-dependent mechanism. Salmonella enteritidis endotoxin (50 micrograms/ml) stimulated a similar increase in TxB2 levels (23 +/- 0.4 ng/ml, P less than 0.05). In contrast to control macrophages, macrophages from endotoxin-tolerant rats stimulated with either NaF or S. enteritidis endotoxin had TxB2 levels that were only 30 and 2% of the respective stimulated control cells. Basal guanosine-triphosphatase (GTPase) activity (33 +/- 6 pmol.mg-1.min-1) in endotoxin-tolerant macrophage membranes was significantly lower (P less than 0.05) than control basal activity (158 +/- 5 pmol.mg-1.min-1). This suppression of macrophage GTPase activity was apparent 48 h after the first in vivo sublethal endotoxin injection (100 micrograms/kg ip). The reduced GTPase activity paralleled in vitro cellular hyporesponsiveness to endotoxin-stimulated TxB2 production.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Homologous desensitization of human platelet thromboxane A2/prostaglandin H2 receptors.

Desensitization of platelet thromboxane (TX)A2/prostaglandin (PG)H2 receptors was induced by incubating platelet-rich plasma with the stable PGH2 analog 11 alpha,9 alpha-(epoxymethano)prosta-5Z,13E-dienoic acid (U46619) (1 microM). Iloprost, a stable prostacyclin analog, was included in the incubation to prevent platelet activation. The TXA2 mimetic, [1S-1 alpha,2 beta(5Z), 3 alpha(1E,3S*), 4 alpha)]-7-[3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl)-7-oxabicyclo - [2.2.1]heptan-2-yl]-5-heptenoic acid (I-BOP), was used to induce platelet aggregation, shape change and increases in intracellular free calcium. The EC50 values for I-BOP-induced rise in intracellular free calcium (control = 10.2 +/- 1.5 nM; desensitized = 79.4 +/- 22.4 nM, n = 6, P less than .05), aggregation (control = 15.8 +/- 2.4 nM; desensitized = 51.7 +/- 11.9 nM; P less than .05, n = 5) and shape change (control = 172 +/- 37 pM; desensitized = 350 +/- 60 pM; P less than .05, n = 7) were increased by the preincubation with U46619. Aggregation responses to thrombin and the calcium ionophore, ionomycin, were unaltered by the preincubation with U46619. Equilibrium binding studies at pH 7.4 revealed a decrease in the number of binding sites for the receptor antagonist 9,11-dimethylmethano-11,12- methano-16(3-iodo-4-hydroxyphenyl)-13,14-dihydro-13-aza-15 alpha beta-omega- tetranor-TXA2 [125I]PTA-OH) (control = 3246 +/- 509 sites/platelet, desensitized = 2198 +/- 324 sites/platelet, n = 6, P less than .05) without a change in affinity.(ABSTRACT TRUNCATED AT 250 WORDS)

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1992

7-[(1R,2S,3S,5R)-6,6-dimethyl-3-(4- iodobenzenesulfonylamino)bicyclo[3.1.1]hept-2-yl]-5(Z)-heptenoic acid: a novel high-affinity radiolabeled antagonist for platelet thromboxane A2/prostaglandin H2 receptors.

A high-affinity thromboxane (TX)A2/prostaglandin (PG) H2 receptor antagonist, I-SAP [7-[(1R,2S,3S,5R)-6,6-dimethyl-3-(4- iodobenzenesulfonylamino)bicyclo[3.1.1]hept-2-yl]-5(Z)-heptenoic acid] and its radiolabeled analog [125I]SAP (Mais et al., 1991) are characterized in the present study. I-SAP antagonized I-BOP ([1S-(1 alpha, 2 beta(5Z),3 alpha(1E,3R*),4 alpha)]-7-[3-(3-hydroxy-4- (4'-iodophenoxy)-1-butenyl)-7-oxabicyclo-[2.2.1]heptan-2y l]-5'heptenoic acid) and U46619 [15S-hydroxy-11 alpha,9 alpha-(epoxymethano)-prosta-5Z,13E-dienoic acid)], two different TXA2/PGH2 mimetics, induced aggregation of washed human platelets in a similar manner (pA2 of 8.11 +/- 0.09, Kd = 7.8 nM, n = 3; pA2 = 8.01 +/- 0.05, Kd = 9.7 nM, n = 8, respectively). I-SAP also had agonistic activity, producing platelet shape change (EC50 = 9.7 nM +/- 0.6 nM at pH 7.4, n = 3) which was blocked by pretreatment of platelets with SQ29548 ([1S-(1 alpha,2 beta(5Z),3 beta,4 alpha)]-7-[3-[[2- [(phenylamino)carbonyl]hydrazino]methyl]-7-oxabicyclo[2.2.1]hept- 2-yl]-5-heptenoic acid), a TXA2/PGH2 receptor antagonist. Radioligand binding studies were performed with [125I]SAP using washed human platelets. Competition of three agonists and four antagonists for binding with [125I]SAP was determined. The compounds showed the appropriate rank order potencies, including stereoselective competition by a pair of stereoisomeric antagonists. In washed human platelets, the Kd for I-SAP was 468 +/- 49 pM and the maximum binding (Bmax) was 2057 +/- 156 sites/platelet at pH 7.4 (n = 6). The Bmax was significantly increased 49% to 3072 +/- 205 sites/platelet at pH 6.5 (P less than .01 but the Kd was unchanged (490 +/- 18 pM, n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)

Binding, Competitive↗
PubMed1991

Endotoxin-induced arachidonic acid metabolism requires de novo protein synthesis and protein kinase C activation.

The mechanisms whereby bacterial endotoxins stimulate arachidonic acid metabolism in macrophages are uncertain. Both protein kinase C activation and de novo protein synthesis occur in macrophages in response to endotoxin. In this study we evaluated the time course and role of protein kinase C and de novo protein synthesis in endotoxin stimulated arachidonic acid metabolism in resident rat peritoneal macrophages. Thromboxane (TX) B2 was measured as the representative arachidonic acid metabolite synthesized in response to Salmonella enteritidis endotoxin, calcium ionophore A23187, or phorbol 12-myristate 13-acetate (PMA). The effect of inhibition of protein kinase C by 1-(5-isoquinolinsulfonyl)-2-methylpiperazine dihydrochloride (H-7) and staurosporine on endotoxin- and A23187-induced TXB2 synthesis was examined. The potential roles of transcriptional and translational events in endotoxin- and A23187-stimulated TXB2 synthesis were determined by utilizing the transcriptional inhibitors camptothecin (10 microM) or actinomycin D (0.08 microM), and the translational inhibitor cycloheximide (0.1 microM). Whereas, A23187 stimulated maximal TXB2 synthesis within 15 min, endotoxin showed a more prolonged time course with a 12-fold increase in TXB2 synthesis above basal levels after 3 h (P less than 0.05). PMA induced an approx. 8-fold increase above basal TXB2 levels that was blocked by inhibition of transcription with actinomycin D. H-7 (10 microM to 50 microM) inhibited endotoxin- and A23187-stimulated eicosanoid synthesis. Staurosporine (0.2 microM) produced a selective 66% inhibition of endotoxin, but not A23187-stimulated TXB2 synthesis. Endotoxin-induced TXB2 production was significantly (P less than 0.05) inhibited by staurosporine, camptothecin, actinomycin D or cycloheximide at intervals from 30 min prior to, through 60 min after endotoxin stimulation. These studies suggest a role for protein kinase C activation and de novo protein synthesis in endotoxin signal transduction events leading to increased macrophage arachidonic acid metabolism. These intracellular events are essential in sustaining the prolonged inflammatory response to endotoxin.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Differential effect of pH on thromboxane A2/prostaglandin H2 receptor agonist and antagonist binding in human platelets.

The effects of changes in pH on the binding of agonists and antagonists to the human platelet thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptor were determined. Competition binding studies were performed with the TXA2/PGH2 mimetic [1S-1 alpha,2 beta (5Z), 3 alpha(1E,3R*),4 alpha)]-7-[3-(3-hydroxy-4'-iodophenoxy)-1-buteny) 7-oxabicyclo-[2.2.1]-heptan-2-yl]-5-heptenoic acid ([125I]BOP). The pH optimum for binding of [125I] BOP to washed human platelets was broad with a range of pH 4-6 in contrast to that of the TXA2/PGH2 receptor antagonist 9,11-dimethyl-methano-11,12-methano-16-(3-iodo-4-hydroxyl)-13-aza-15 alpha,beta-omega-tetranorthromboxane A2 ([125I]PTA-OH) which was 7.4. Scatchard analysis of [125I]BOP binding in washed platelets at pH 7.4, 6.0, and 5.0 revealed an increase in affinity (Kd = 1.16 +/- 0.06, 0.64 +/- 0.09, and 0.48 +/- 0.05 nM, respectively) and an increase in the number of receptors (Bmax = 2807 +/- 415, 5397 +/- 636, and 7265 +/- 753 sites/platelet, respectively). The potency of I-BOP to induce shape change in washed platelets at pH 6.0 was also significantly increased from an EC50 value of 0.34 +/- 0.016 nM at pH 7.4 to 0.174 +/- 0.014 nM at pH 6.0 (n = 6, p less than 0.05). In contrast, the EC50 value for thrombin was unaffected by the change in pH. In competition binding studies with [125I]BOP, the affinity of the agonists U46619 and ONO11113 were increased at pH 6.0 compared to 7.4. In contrast, the affinity of the TXA2/PGH2 receptor antagonists I-PTA-OH, SQ29548, and L657925 were either decreased or unchanged at pH 6.0 compared to 7.4. Diethyl pyrocarbonate and N-bromosuccinimide, reagents used to modify histidine residues, reversed the increase in affinity of [125I]BOP at pH 6.0 to values equivalent to those at pH 7.4. In solubilized platelet membranes, the effects of NBS were blocked by coincubation with the TXA2/PGH2 mimetic U46619. The results suggest that agonist and antagonist binding characteristics are different for the TXA2/PGH2 receptor and that histidine residue(s) may play an important role in the binding of TXA2/PGH2 ligands to the receptor.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1991

Platelet and vascular thromboxane A2/prostaglandin H2 receptors. Evidence for different subclasses in the rat.

Thromboxane A2 (TXA2) and its precursor prostaglandin H2 (PGH2) induce platelet aggregation and vascular contraction through shared cell surface receptors commonly referred to as TXA2 or TXA2/PGH2 receptors. Whether different subclasses of TXA2/PGH2 receptors exist in platelets and vascular smooth muscle cells is controversial. In this study, TXA2 receptors on washed rat and human platelets and cultured rat aortic smooth muscle cells (RASMC) were characterized using radioligand competition binding assays with the 125I-labeled TXA2/PGH2 receptor agonist [1S-(1 alpha,2 beta(5Z),3 alpha(1E,3R*),4 alpha)] -7- [3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl) -7- oxabicyclo-[2.2.1]- heptan-2-yl] -5- heptenoic acid (I-BOP) and various agonists and antagonists. Scatchard analyses of equilibrium binding data revealed Kd values of 205 +/- 68 pM (N = 6), 2.2 +/- 0.3 nM (N = 9) and 310 +/- 60 pM (N = 7) and Bmax values of 1.3 +/- 0.45 fmol/10(6) platelets, 2.8 +/- 0.2 fmol/10(6) platelets and 20.9 +/- 2.2 fmol/10(6) cells for rat and human platelets and RASMC, respectively. Concentration-dependent increases in intracellular free Ca2+ concentrations induced by I-BOP were observed in RASMC loaded with the calcium sensitive dye fura-2. The IC50 values for various TXA2/PGH2 analogues in competition binding assays with 125I-BOP were determined. Based on their IC50 values, the rank orders were I-BOP less than L657925 less than ONO11113 less than or equal to SQ29548 less than PTA-TPO less than PTA-NO less than or equal to L657926 less than or equal to I-PTA-OH less than PTA-OH[2] = meta-I-PTA-PO less than or equal to ONO11120[2] = ONO11120[1] less than PTA-OH[1] in rat platelets. I-BOP less than SQ29548 less than PTA-TPO = L657925 less than or equal to ONO11113 less than I-PTA-OH less than PTA-NO less than or equal to meta-I-PTA-PO less than or equal to PTA-OH[2] less than ONO11120[2] less than or equal to ONO11120[1] less than L657926 less than or equal to PTA-OH[1] in human platelets, and I-BOP less than L657925 less than ONO11113 less than or equal to SQ29548 less than ONO11120[2] less than or equal to L657926 less than or equal to PTA-OH[2] less than PTA-TPO less than ONO11120[1] less than I-PTA-OH less than meta-I-PTA-PO less than PTA-NO less than PTA-OH[1] in RASMC.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Effect of the LTD4 receptor antagonist LY203647 on endotoxic shock sequelae in the rat.

This study investigated the effect of a novel LTD4 receptor antagonist LY203647 on Salmonella enteritidis endotoxin-induced shock sequelae in anesthetized rats. LY203647 (30 mg/kg i.v.) or vehicle was given 10 min prior to endotoxin (10 mg/kg i.v.) or its vehicle, and the hematocrit, mean arterial pressure and circulating leukocyte counts were determined. LY203647 significantly inhibited endotoxin-induced hemoconcentration up to 90 min post-endotoxin (46.7 +/- 1.3 vs. 51.9 +/- 2.4% at 30 min post-endotoxin, 45.9 +/- 1.1 vs. 53.1 +/- 1.4% at 90 min post-endotoxin, N = 8-9, P less than 0.05). The endotoxin-induced decreases in mean arterial pressure were also attenuated by LY203647, -29 +/- 5 vs. -56 +/- 9 mm Hg at 60 min post-endotoxin and -42 +/- 4 vs. -60 +/- 9 mm Hg at 90 min post-endotoxin (N = 9-10, P less than 0.05). LY203647 also attenuated endotoxin-induced decreases in leukocyte count in arterial blood. A study of differential counts in circulating leukocytes (N = 3) showed that endotoxin induced complete disappearance in circulating neutrophils. The circulating lymphocyte count was decreased by 30 +/- 10 and 41 +/- 1% at 15 and 30 min post-endotoxin, respectively. LY203647 inhibited endotoxin-induced lymphopenia (P less than 0.05) but failed to alter endotoxin-induced neutropenia. These data suggest that LTD4 may play an important role in mediating hemoconcentration, hypotensive and lymphocytopenic sequelae of endotoxin shock.

Acetophenones↗
PubMed1991

Interactions of dihydropyridine Ca2+ channel agonists with the human platelet thromboxane A2/prostaglandin H2 receptor.

The specific interactions at the human platelet thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptor by four 1-4 dihydropyridine (DHP) agonists were studied. Using competition equilibrium binding assays with the TXA2/PGH2 receptor agonist [125I]BOP and the antagonist [125I]PTA-OH, the affinities of racemic BAY K 8644 (BAY), racemic CGP 28392 (CGP) and (+) and (-) SDZ 202-791 (SDZ) for the TXA2/PGH2 receptor were determined. The rank order potencies for competition were BAY greater than (-)SDZ greater than CGP greater than or equal to (+)SDZ. Bay, CGP and SDZ (stereoselectively) inhibited specific incorporation of the TXA2/PGH2 receptor photoaffinity probe [125I]PTA Azido into three proteins associated with the TXA2/PGH2 receptor with Mr of 43, 39 and 27 kDa as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis autoradiography. Using the fluorescent Ca2+ probe Fura-2, it was observed that I-BOP failed to stimulate classical divalent cation channels. However, SDZ stereoselectively inhibited the rise in [Ca2+]i induced by I-BOP while not affecting that induced by thrombin. Although DHPs specifically and stereoselectively interact with the TXA2/PGH2 receptor on human platelets, the TXA2/PGH2 receptor-mediated rise in [Ca2+]i is not through stimulation of a classical divalent cation channel.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1991

Thromboxane A2 receptors are influenced by cell density in cultured rat aortic smooth muscle cells.

The influence of cell density on the binding characteristics of thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors in rat aortic vascular smooth muscle cells in culture were determined using [1S- (1 alpha, 2 beta (5Z), 3a (1E, 3R*), 4 alpha)]- 7 -[3- (3-hydroxy -4- (4'-iodophenoxy)-1-butenyl)-7-oxabicyclo-[2.2.1]heptan- 2yl]-5-heptenoic acid (125I-BOP). The Bmax for 125I-BOP was 5,430 +/- 139 sites/cell (26.9 +/- 5.7 fmoles/mg protein) for cells cultured in 1% fetal calf serum and 2809 +/- 830 sites/cell (13.1 +/- 2.2 fmoles/mg protein) for cells cultured in 10% fetal calf serum. Cells were allowed to grow to varying densities and then harvested for assay. There was a negative correlation between the Bmax and the cell density per flask. The Kd for I-BOP did not significantly vary in any of the studies. The results demonstrate that cell density plays an important role in influencing the expression of vascular TXA2/PGH2 receptors.

Animals↗
PubMed1991

Endotoxin tolerance differentially alters hemodynamic responses to a thromboxane A2 mimetic and phenylephrine.

Repeated sublethal doses of endotoxin render rats tolerant to lethal doses of endotoxin and reduce thromboxane (Tx) A2 synthesis. Endotoxin-tolerant rats are also more resistant to lethal doses of U46619, a stable TxA2 mimetic. These observations raised the possibility that tolerance may alter hemodynamic responses to TxA2 via one or more mechanisms. Mean arterial pressure (MAP) responses to i.v. injections of the stable TxA2 mimetic U46619 at doses ranging from 0.17 to 8.4 micrograms/kg were determined. Despite an initial lower systemic vascular resistance in tolerant rats compared to control rats (2.4 +/- 0.3 vs 3.1 +/- 0.2 mm Hg/ml/min/100 g of body weight, respectively, p less than 0.05), the maximum pressor response to U46619 was significantly greater (p less than 0.05) at the higher doses of U46619 in tolerant rats compared to control rats. Tolerant and control rats also exhibited qualitatively different changes in MAP in response to U46619. Control rats manifested an initial hypotensive response (15 s) not observed in tolerant rats. In contrast, tolerant rats exhibited no depressor response, but a higher peak pressor response to U46619 than that seen in controls. Since prostaglandins may modulate vascular responses to U46619, subsequent studies were conducted in indomethacin-pretreated or essential fatty acid (EFA) deficient rats that were depleted of arachidonic acid substrate. Either indomethacin or EFA deficiency significantly prevented the initial hypotensive response in control rats, suggesting that prostaglandins may mediate this response to U46619. In additional studies, the MAP response in tolerant and control rats to the alpha 1-adrenergic agonist phenylephrine was determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Agonists↗
PubMed1991

Testosterone increases thromboxane A2 receptors in cultured rat aortic smooth muscle cells.

Previous studies have demonstrated increased contractile responses to thromboxane A2 (TXA2) mimetics in aortas obtained from male rats compared with those obtained from females. This study was designed to determine the effects of testosterone and 17 beta-estradiol treatment on TXA2 receptors in cultured rat aortic smooth muscle cells (RASMCs). TXA2 receptor affinity and density were determined through equilibrium binding experiments using the TXA2/prostaglandin H2 mimetic [1S-(1 alpha,2 beta(5Z),3 alpha(1E,3R*),4 alpha)]-7-[3-(3- hydroxy-4-(4'-125iodophenoxy)-1-butenyl)-7-oxabicyclo[2.2.1]hep tan-2-yl]- 5-heptenoic acid (125I-BOP). Incubation with testosterone (100 nM) for 24 or 48 hours resulted in a significant (p less than 0.05) 31% and 48% increase in TXA2 receptor density without any change in affinity. 17 beta-Estradiol (100 nM) had no significant effect on either the density or affinity of TXA2 receptors. Coincubation with the testosterone receptor antagonist hydroxyflutamide (1 microM) blocked the testosterone-induced increase in TXA2 receptor density. The maximum increase in intracellular free calcium induced by I-BOP was significantly (p less than 0.05) greater in testosterone-treated RASMCs than controls. Similarly, increases in inositol trisphosphate induced by the TXA2/prostaglandin H2 mimetic U46619 were significantly (p less than 0.05) greater in testosterone-treated RASMCs compared with controls. The results demonstrate that testosterone increases vascular TXA2 receptor density and support the notion that sex steroid hormones modulate the expression of this receptor.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1991

Prostacyclin and thromboxane A2 formation is increased in human sepsis syndrome. Effects of cyclooxygenase inhibition.

Arachidonic acid metabolites, especially thromboxane-A2 and prostacyclin, have been shown to be increased in experimental models of sepsis and the adult respiratory distress syndrome (ARDS) and play a major pathophysiologic role. This study was designed to determine if these metabolites are increased in human sepsis syndrome and if inhibition of fatty acid cyclooxygenase affects their formation and their pathophysiologic sequelae. We conducted a double-blind, placebo-controlled trial of ibuprofen (800 mg given rectally every 4 h for three doses) in 30 patients with sepsis syndrome defined by abnormal vital signs, the appearance of serious infection, and at least one major organ failure. Urinary concentrations of the metabolite of thromboxane-A2, 2,3-dinor-TxB2, and prostacyclin, 2,3-dinor-6-keto-prostaglandin F2 alpha, were elevated 10 to 20 times normal and declined to four to five times normal by 12 h after entry in the ibuprofen-treated group and remained elevated in the placebo-treated patients. The urinary concentration of TxB2 and 6-keto-prostaglandin F1 alpha, which reflect renal production of TxA2 and prostacyclin, respectively, were also increased approximately 10-fold over normal and were subsequently decreased by ibuprofen. Coincident with the reduction in metabolite levels, the ibuprofen-treated group, but not the placebo-treated group, experienced a significant decline in temperature, heart rate, and peak airway pressure, and a trend towards more rapid reversal of shock (p = 0.12).(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclooxygenase Inhibitors↗
PubMed1991

Effect of a LTD4 receptor antagonist in porcine septic shock.

The effect of a selective LTD4 receptor antagonist SK & F104353 was studied in septic pigs anesthetized with isoflurane. Yorkshire pigs (25.2 +/- 2.3 kg) were instrumented and monitored for cardiac output (CO), mean arterial pressure (MAP), systemic vascular resistance (SVR), mean pulmonary arterial pressure (MPAP), pulmonary vascular resistance (PVR), renal artery blood flow (RABF), renal vascular resistance (RVR), arterial PO2, and extravascular lung water (EVLW). Blood samples were also collected for platelet, white blood cell and hematocrit determinations and plasma was assayed for thromboxane (TX) B2. Sepsis was induced by infusion of Pseudomonas aeruginosa (3 x 10(8) CFU%kg/h) for 2 h. Cardiovascular and hematologic data were determined at 30 min intervals for 4 h. Groups were infused with either SK & F104353 (3 mg/kg/h; n = 5) or drug vehicle (n = 6) beginning 15 min prior to infusion with the P. aeruginosa. In the vehicle group beginning at -90 min after sepsis induction, there was a 30 +/- 7% decrease of CO, a 27 +/- 5.0% decrease of MAP, and a 44 +/- 7% decrease of RABF, whereas, MPAP increased to 147 +/- 37% and plasma TXB2 increased from less than 200 pg/ml to 3,049 +/- 367 pg/ml (P less than 0.05). The EVLW and hematocrit increased (P less than 0.05), and the arterial PO2, white blood cell count, and platelet count decreased with the severity of the sepsis. In pigs pretreated with SK & F104353 the MAP and RABF were transiently improved (P less than 0.05), and the decrease in arterial PO2 was delayed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of LTB4 receptor antagonists in endotoxic shock in the rat.

This study examined 1) the effects of infusion of LTB4 and 2) the potential role of LTB4 in the sequelae to endotoxic shock in the rat. Control rats were anesthetized with Ketamine/xylazine and given LTB4 (2 micrograms/kg) bolus i.v. followed by a 1 microgram/kg/min infusion for 10 min. LTB4 induced systemic hypotension and a three-fold increase in circulating band neutrophils which contributed to a 70% increase (P less than 0.05) in the total peripheral neutrophil count. LTB4 did not cause changes in circulating mature (segmented) neutrophils, lymphocytes, platelets, or hematocrits. Pretreatment (1 min) with LY233978, an LTB4 antagonist (10 mg/kg bolus i.v.), inhibited LTB4-induced systemic hypotension (-16.1 +/- 6.1 mmHg [n = 3] vs. -38.8 +/- 5.9 mmHg [n = 4], P less than 0.05). Salmonella enteritidis endotoxin (10 mg/kg bolus i.v.) induced systemic hypotension, hemoconcentration, leukopenia, and thrombocytopenia, which was greatest at 5 and 15 min postendotoxin. The leukopenia was characterized by lymphopenia, band neutropenia, and segmented neutropenia. LY233978 (10 mg/kg bolus i.v. immediately before endotoxin administration and followed by an infusion at 0.67 mg/kg/min for 90 min) attenuated endotoxin-induced hemoconcentration at 60 and 90 min postendotoxin (P less than 0.05), and systemic hypotension at 15 min postendotoxin (P less than 0.05). The LTB4-receptor antagonist LY255283 (10 mg/kg bolus i.v., 10 min before endotoxin followed by a 5 mg/kg bolus i.v. 30 min postendotoxin) completely inhibited endotoxin-induced systemic hypotension and partially attenuated endotoxin-induced hemoconcentration from 15 min to 90 min postendotoxin (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effects of a linseed oil enriched diet on endotoxin-induced sequelae: differential in vitro and in vivo effects.

Endotoxin stimulates macrophages to synthesize membrane-associated inflammatory mediators including eicosanoids and procoagulant activity (PCA). Alpha linolenic acid, a component of linseed oil, is metabolized to eicosapentaenoic acid, which may replace arachidonic acid in membrane phospholipids. Thus, ingestion of linseed oil may alter the generation of eicosanoids, PCA and other membrane-dependent responses. This study compared the in vitro endotoxin-induced synthesis of eicosanoids and expression of PCA by peritoneal macrophages obtained from rats fed a control diet and rats fed a diet enriched with linseed oil. The effect of endotoxin on in vivo plasma eicosanoid concentrations, leukogram, and microvascular permeability were determined. Endotoxin (5 ug/ml) stimulated synthesis of iTxB2, i6-keto PGF1 alpha and expression of PCA by macrophages in vitro. These in vitro responses of macrophages from linseed oil fed rats were significantly less than those of macrophages from control rats. In contrast, there were no significant differences in in vivo responses to endotoxin. The fatty acid composition of total lipids and phospholipids in liver and plasma from linseed oil fed rats and control rats were not different. These composite data suggest several possibilities: (1) linseed oil may have effects independent of alpha-linolenic acid on macrophage function, (2) linseed oil may alter the fatty acid composition of macrophage phospholipids prior to changing that of other tissues, and (3) the reduced in vitro responses of peritoneal macrophages may not reflect the systemic responses to endotoxin.

6-Ketoprostaglandin F1 alpha↗