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Biomedical subjects

D Shepro

Publications and source records attributed to D Shepro.

At least 91 records · Page 5Linked to original sources
PubMed1988

Effects of nitroprusside and ketanserin upon pulmonary edema after acid injury.

Increased hydrostatic pressure and microvascular permeability after acid aspiration as causes of pulmonary and tracheobronchial edema were studied. Eighteen dogs were anesthetized and 3.0 milliliters per kilogram of 0.1 normal hydrochloride instilled into the trachea. After one hour, the platelet count decreased 47,500 per cubic millimeter (p less than 0.05) from base line levels of 221,400 per cubic millimeter and platelet serotonin stores decreased from 2.09 to 1.65 micrograms per 10(9) platelets (p less than 0.05). Mean pulmonary arterial pressure increased progressively from a base line value of 11 to 21 millimeters of mercury four hours after acid instillation (p less than 0.05). Mean arterial pressure fluctuated from a high of 143 millimeters of mercury to the final value, at four hours, of 119 millimeters of mercury. Ketanserin, a serotonin receptor antagonist, infused one hour after acid injury did not prevent release of platelet 5 hydroxytryptamine but led to a 24 per cent decrease in mean pulmonary arterial pressure from 13 to 10 millimeters of mercury (p less than 0.05) and an 11 per cent decrease in mean arterial pressure from 135 to 120 millimeters of mercury (p less than 0.05). Nitroprusside produced a 30 per cent decrease in mean arterial pressure, but only a 20 per cent decline in mean pulmonary arterial pressure (p less than 0.05). Four hours after acid was instilled, untreated dogs produced 129 milliliters of edema fluid from the endotracheal tube. In proportion to the relative decline in mean pulmonary arterial pressure, nitroprusside therapy reduced the volume of edema to 72 milliliters (p less than 0.05) and ketanserin to 52 milliliters (p less than 0.05). These results suggest that 5 hydroxytryptamine contributes to the pulmonary hypertension associated with acid injury and that the volume of edema formed may be directly related to the increase in the hydrostatic pressure.

Animals↗
PubMed1987

Serotonin induced actin polymerization and association with cytoskeletal elements in cultured bovine aortic endothelium.

Serotonin, (5-hydroxytryptamine, 5-HT) binds to cultured endothelial cell stress fibers as identified by fluorescence microscopy and in vitro induces actin polymerization as measured by DNase 1 inhibition and differential centrifugation; the structural change in actin in the presence of 5-HT resembles actin paracrystals as visualized by negative staining under electron microscopy. These observations indicate that 5-HT, which is taken up by endothelium by a non-mediated diffusion, may interact directly with actin to affect cytoskeletal changes.

Actins↗
PubMed1987

Correlation among endothelial cell shape, F-actin arrangement, and prostacyclin synthesis.

Though many factors have been identified which modulate prostacyclin (PGI2) synthesis, there is little information on cellular mechanisms whereby endothelial cells (EC) regulate their basal eicosanoid metabolism. Using substrates of various adhesive capacities, bovine and porcine aortic EC shape and cytoskeletal F-actin arrangement could be modulated. Staining with rhodamine-phalloidin (R-P) permitted analysis of F-actin arrangement, while differences in cell shape were determined by measurement of cell perimeter surface area (CPSA). Spectrophotoflurometric measurements were used to quantitate the R-P binding capacity of the cultures. Cultures of reduced CPSA (225.2 +/- 13.5 mu2) generated the highest levels of basal PGl2 (6.14 +/- 0.51 pg/ug cell protein); had a diffuse arrangement of F-actin and an increased binding capacity for R-P (463.55 +/- 50.58 nmoles/ug cell protein). Cultures of enlarged CPSA (1399.3 +/- 148.3 mu2), with many actin cables and a significantly reduced (p less than 0.001) R-P binding capacity (74.941 +/- 11.79 nmoles/ug of cell protein) produced significantly smaller (p less than 0.001) basal quantities of PGl2 (1.33 +/- 0.14 pg/ug cell protein). Similarly, arachidonic acid stimulation of cultures of reduced CPSA resulted in an increased synthesis of PGl2 when compared to stimulated cultures of enlarged cells. These findings suggest a role for cell shape and the cytoskeleton in the mechanism controlling PGl2 production and indicate that alteration of the arrangement of F-actin may be of importance in regulation of EC eicosanoid metabolism.

Actins↗
PubMed1987

Microvascular pericyte contractility in vitro: comparison with other cells of the vascular wall.

Collagen lattices containing bovine retinal pericytes (RPs), vascular smooth muscle cells (VSMCs), pulmonary microvessel endothelial cells (PMECs), or aortic endothelial cells (AECs) were prepared and contraction was quantitated by measuring the resulting change in lattice area. VSMCs were the most efficient at lattice contraction followed by RPs and then PMECs. AECs did not contract the lattices. To document further that these observations represent contraction, cells were grown on inert silicone rubber sheets. Substratum wrinkling was indicative of tension development and quantitated as percent of cells contracted. RPs were more contractile than PMECs, and AECs were incapable of developing tension. VSMCs were less contractile than RPs, unlike the comparative contractility observed with the lattice system. Alteration of actin-containing filaments by cytochalasin B significantly reduced RP contraction of silicone rubber and inhibited their contraction of collagen lattices in a dose-dependent manner. Rhodamine-phalloidin staining of contracting RPs revealed microfilament bundle orientations that suggested their association in the force applied for contraction. RP, VSMC and PMEC contraction of collagen lattices was directly proportional to the concentration of fetal calf serum. Also, RP contraction was greater in calf serum than calf plasma-derived serum, an indication that RPs respond to substances that appear continuously and episodically in blood. These in vitro findings support the theory that pericytes in vivo are contractile but that endothelial cells may also contribute to microvascular tonus.

Animals↗
PubMed1987

Vasodilator prostaglandins (PG) prevent renal damage after ischemia.

Thromboxane (Tx) synthase but not cyclo-oxygenase inhibitors prevent acute tubular necrosis (ATN) after renal ischemia, a phenomenon believed to be due to stimulation of the endogenous production of vasodilating prostaglandins (PG). This study directly tests that vasodilating PG protect against the consequences of renal ischemia. Anesthetized, 500-g rats had right nephrectomy and 45 minutes of left renal pedicle clamping or sham clamping. The rats were treated with intravenous (I.V.) saline 1.9 mL/h starting 40 minutes after clamping or sham clamping. All rats except the sham group (N = 8) were pretreated 1 hour before ischemia with ibuprofen (12 mg/kg) to prevent prostanoid synthesis. Beginning 5 minutes before clamp release, the rats were treated intravenously for 2 hours with: saline vehicle (N = 9), PGE1 400 ng/kg/min (N = 6), nitroprusside 4 micrograms/kg/min (N = 8), or dopamine 3 micrograms/kg/min (N = 11). After 24 hours, sham rat creatinine level was 0.5 mg/dL and weight of the left kidney was 86.5% of the previously removed right kidney. Compared with sham rats, ischemia and saline treatment resulted in a rise in creatinine level to 2.7 mg/dL (p less than 0.05) and a rise in kidney weight to 101.9% (p less than 0.05); PGE1 led to a creatinine level of 1.1 mg/dL, a value lower than that of the rats treated with saline (p less than 0.05), and a kidney weight of 92.0%, a value similar to that of sham rats; nitroprusside and dopamine led to a rise in creatinine levels to 3.2 mg/dL (p less than 0.05) and 2.3 mg/dL (p less than 0.05), respectively, as well as a rise in kidney weight to 108.0% (p less than 0.05) and 105.4% (p less than 0.05), respectively. Histologic examination showed ATN in rats treated with saline, nitroprusside, and dopamine, but not in rats treated with PGE1. These results indicate that PGE1 protects the cyclo-oxygenase-treated kidney against ischemia-induced ATN.

Acute Kidney Injury↗
PubMed1987

Pulmonary leukosequestration induced by hind limb ischemia.

Lower torso ischemia leads to acute respiratory failure, an event associated with the accumulation of inflammatory cells in the lungs. This study tests whether ischemia-induced eicosanoid synthesis leads to polymorphonuclear leukocyte (PMN) accumulation in the lungs. Anesthetized rats (N = 51) were randomized into five groups: nonischemic sham rats (N = 10); the remaining four groups were rats made ischemic for 4 hours with bilateral thigh tourniquets treated just before tourniquet release with saline vehicle (N = 17): the thromboxane (Tx) synthase inhibitor OKY-046 (Ono Pharmaceutica, Osaka, Japan) 2 mg/kg intravenously every 2 hours (N = 8); the lipoxygenase inhibitor diethylcarbamazine (DEC) (Sigma, St. Louis, MO) 0.2 mg/kg/min intravenously (N = 8); the platelet-activating factor receptor antagonist SRI (Sandoz Inc., East Hanover, NJ) 63-072 3 mg/kg intravenously every 30 minutes (N = 8). Four hours after ischemia, plasma TxB2 levels in the ischemic placebo-treated group was 3570 +/- 695 pg/mL, compared with 495 +/- 73 pg/mL in sham rats (p less than 0.001). Lung microscopy showed foci of proteinaceous exudate in alveoli and 121 +/- 10 PMN/20 high power fields (HPF) compared with 59 +/- 9 PMN/20 HPF in the sham group (p less than 0.001). One day after ischemia PMN accumulations remained elevated at 119 PMN/20 HPF. Pretreatment with OKY-046 led to reduced TxB2 levels of 149 +/- 17 pg/mL, normal lung histology, and 83 +/- 13 PMN/20 HPF, a value similar to that of the sham group and lower than that of the placebo-treated group (p less than 0.05). Treatment with DEC yielded TxB2 levels of 1419 +/- 492 pg/mL, which was lower than that of the placebo group (p less than 0.05) but higher than that of the sham group (p less than 0.05). Microscopy showed normal lungs with 79 +/- 7 PMN/20 HPF lower than the placebo group (p less than 0.05). SRI 63-072 did not inhibit Tx synthesis or leukosequestration in the lungs. Platelet counts decreased in all groups relative to sham animals (p less than 0.05). The results indicate that Tx synthesis induced by ischemia moderates PMN accumulations in the lungs. Inhibition of lipoxygenase is believed to prevent PMN accumulations both by limiting leukotriene-induced Tx synthesis as well as by limiting production of chemoattractants.

Animals↗
PubMed1987

Pulmonary hypertension and leukosequestration after lower torso ischemia.

Ischemia stimulates thromboxane (Tx) synthesis. This study tests the hypothesis that the cardiopulmonary dysfunction that may follow aortic declamping is related to Tx. Anesthetized dogs (N = 15) were subjected to 4 hours of infrarenal aortic cross-clamping. In untreated control animals (N = 7), plasma levels of TxB2 rose from 654 +/- 74 pg/mL to 1238 +/- 585 pg/mL at 5 min (p less than 0.05), and to 3174 +/- 912 pg/mL 3 hours after declamping (p less than 0.05). Mean pulmonary artery pressure (MPAP) rose 5 min after declamping from 13 +/- 2 mmHg to 21 +/- 2 mmHg (p less than 0.05). Cardiac Index (CI) declined during ischemia from 181 +/- 30 mL/kg.min to 128 +/- 16 mL/min.kg (p less than 0.05), and to 80 +/- 8 mL/min.kg after 4 hours of reperfusion (p less than 0.05). Platelet counts declined but platelets labeled with In 111 did not accumulate in the lungs, whereas quantitative counts of polymorphonuclear leukocytes (PMN) in the lungs 4 hours after declamping yielded 213 +/- 33 PMN/25 high power fields (HPF) in dependent areas of the lung and 153 +/- 26 PMN/25 HPF in nondependent areas. The wet/dry weight ratio of the lungs was not elevated, although foci of proteinaceous exudate and PMNs in alveoli were noted. Another group of dogs (N = 8) were pretreated by random choice with the Tx synthase inhibitor OKY-046 2 mg/kg IV every 2 hours, which led to: lower TxB2 levels at baseline 95 +/- 35 pg/mL (p less than 0.05), 5 min after ischemia 140 +/- 93 pg/mL and after 3 hours of reperfusion 122 +/- 36 (p less than 0.05); lower MPAP, 16 +/- 2 mmHg (p less than 0.05); higher CI throughout (p less than 0.05); normal histology and reduced pulmonary PMN sequestration both in dependent 127 +/- 15 PMN/25 HPF and nondependent areas of the lungs 95 +/- 11 PMN/25 HPF (p less than 0.05). In animals undergoing sham ischemia (N = 3), levels of TxB2 and cardiopulmonary function remained unchanged from baseline. There were 150 PMN/25 HPF in dependent and 85 PMN/25 HPF in nondependent lung areas. The results indicate that ischemia-generated Tx mediates a rise in MPAP, a fall in CI, and PMN entrapment in the lungs.

Animals↗
PubMed1987

Vasoactive amines directly modify endothelial cells to affect polymorphonuclear leukocyte diapedesis in vitro.

Bovine aortic endothelial cells were cultured on the basement membrane surface of amnionic membrane and used as a substrate for polymorphonuclear leukocyte (PMN) diapedesis in vitro. Norepinephrine (NE), serotonin (5HT), or phalloidin treatment of the endothelial cells (ECs) reduces, whereas histamine or cytochalasin B increases, the number of PMNs migrating across the ECs and amnionic membrane. In contrast, amine treatment of PMNs or acellular amnionic membrane does not alter PMN diapedesis or chemotaxis. The NE and histamine effects are blocked by appropriate receptor antagonists, but the 5HT effect is not. All the agents' effects are also reversible. Qualitatively similar effects on EC permeability to Evan's blue-labeled albumin occur with all agents; however, PMN adhesion to ECs is not affected. Previously, we reported that NE and 5HT increase stress fiber numbers and decrease EC permeability to macromolecules in vitro, whereas histamine has the opposite effects, and that NE and 5HT eliminate the erythrocyte extravasation associated with thrombocytopenia in vivo. In this study, we propose that these vasoactive amines also alter PMN diapedesis in vitro through a direct effect on the EC, in part due to alterations in the EC cytoskeleton.

Animals↗
PubMed1987

A high plasma prostaglandin to thromboxane ratio protects against renal ischemia.

Pretreatment with the thromboxane synthase inhibitor OKY-046 but not the cyclo-oxygenase inhibitor ibuprofen protects against ischemia-induced acute tubular necrosis. However, ibuprofen together with the vasodilating agent prostaglandin E1 is protective. This suggests that a high prostaglandin to thromboxane ratio is the major factor operative in preventing tubular necrosis, the subject of this study. Rats that had unilateral nephrectomy (n = 60) with the exception of rats that had sham operations (n = 8) underwent 45 minutes of left renal pedicle clamping. Thirty minutes before the operation, the rats received either a saline solution or a thromboxane synthase inhibitor that was given intravenously. The inhibitors OKY-046 (2 milligrams per kilogram, n = 10), UK38485 (1 milligram per kilogram, n = 9) and U63357A (10 milligrams per kilogram, n = 10) were given as a single bolus while the inhibitor CGS13080 (0.1 milligram per kilogram, n = 9, and 1.0 milligram per kilogram, n = 7) was given by constant infusion and continued for 60 minutes after reperfusion. With saline solution therapy, five minutes after reperfusion, thromboxane B2 increased from 154 to 2,537 picograms per milliliter (p less than 0.00001) and 6-keto-prostaglandin F1 alpha increased from 51 to 266 picograms per milliliter (p less than 0.004). At 24 hours, the creatinine level increased from 0.5 to 2.8 milligrams per deciliter (p less than 0.00001). Only OKY-046 yielded a creatinine level at 24 hours of 1.2 milligrams per deciliter, a value lower than that for those in the saline solution control group (p less than 0.002). Furthermore, OKY-046 led to the highest prostaglandin to thromboxane ratio (p less than 0.035). The five other ratios which occurred after drug therapy were inversely related to the decrease in the creatinine value (r = -0.93, p less than 0.02). Histologically, OKY-046 was the only thromboxane synthase inhibitor to prevent acute tubular necrosis (p less than 0.05). Results show that a high prostaglandin to thromboxane ratio protects against acute tubular necrosis.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Serotonin, norepinephrine, and histamine mediation of endothelial cell barrier function in vitro.

The effects of serotonin (5-hydroxytryptamine, 5-HT), norepinephrine (NE), and histamine on endothelial cell barrier function were examined in vitro. Bovine aortic endothelial (BAE) cells grown to confluence on microcarriers formed a measurable barrier to the passage of a trypan blue dye-bovine serum albumin conjugate (TB-BSA) from the culture medium into the microcarrier matrix. Vascular smooth muscle (VSM) cells or Swiss 3T3 fibroblasts impeded TB-BSA diffusion only 42% and 56%, respectively, relative to BAE cells. These results suggest that barrier formation may be an endothelial cell-specific phenomenon. Treatment of BAE cells with histamine was associated with 2- to 3-fold increases in the rate of TB-BSA diffusion. In contrast, treatment with 5-HT or NE at concentrations ranging from normal to pathophysiological circulating plasma levels significantly impeded TB-BSA diffusion by up to 43% and 33%, respectively, relative to untreated controls. The barrier-modulating effects of the vasoactive amines were dose-dependent, cell-specific, and in some cases appear to be receptor-mediated. These results are consistent with previous reports that histamine increases vascular permeability in part by affecting diffusion between endothelial cells; they support the hypothesis that 5-HT and NE contribute to the maintenance of the endothelial barrier in vivo.

Animals↗
PubMed1986

Cyclo-oxygenase products mediate hypoxic pulmonary hypertension.

High-risk infants with a fetal pattern of circulation demonstrate hyperactivity of the pulmonary vascular bed in response to stimuli including mucous plugging, atelectasis, and endotrachial tube suctioning. The resultant increase in pulmonary vascular resistance (PVR) leads to pulmonary hypertension, severe right-to-left shunting, and hypoxemia. Stimuli that trigger pulmonary hypertension cause hypoxia, suggesting the importance of hypoxic pulmonary vasoconstriction (HPV). Although many humoral mediators of HPV have been hypothesized, none have been proven. This study investigates the possible role of the cyclo-oxygenase derivatives thromboxane A2 and prostacyclin as determinants of hypoxic pulmonary hypertension. Open-chested lambs were ventilated with 13% O2 prior to and following treatment with OKY 046, a selective thromboxane inhibitor. In untreated lambs, the partial pressure of arterial oxygen fell from 80 +/- 27 (mean +/- SD) to 35 +/- 13 mm HG (P less than .01). The mean arterial pressure (MAP) remained at 50 +/- 7 mm HG, and the cardiac output (CO) was unchanged at 0.8 +/- 0.2 L/min. The mean pulmonary arterial pressure (MPAP) rose from 11 +/- 4 to 20 +/- 4 mm HG (P less than .01) whereas the PVR increased 70% (P less than .01). TxB2 rose from 147 +/- 85 to 271 +/- 154 pg/mL (P less than .05), and 6-keto-PGF1 alpha rose from 105 +/- 96 to 142 +/- 110 pg/mL. These substances are the hydrolysis products of TxA2 and prostacyclin respectively. In animals treated with OKY 046 prior to ventilation with 13% O2, values for MAP, CO, and PVR were similar to those of the nontreatment period.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Heterogeneity of intimal and microvessel endothelial cell barriers in vitro.

We have compared the barriers provided by bovine aortic endothelial cells (AEC), cerebral microvessel endothelial cells (CMEC), and pulmonary microvessel endothelial cells (PMEC) cultured on microcarriers to the passage of trypan blue-bovine serum albumin (TB-BSA). AEC and PMEC barriers were quantitatively comparable, and significantly more permeable to TB-BSA than the CMEC barrier. Serotonin, norepinephrine, and histamine, shown to modulate the AEC barrier, had no effect on the CMEC barrier to TB-BSA. These results suggest that cultured endothelial cells (EC) retain region-specific phenotypic modifications of barrier function observed in vivo. Glutaraldehyde-fixed EC and EC kept at 4 degrees C to minimize transcytosis displayed TB-BSA passage that was reduced by less than 30%, which indicated that the bulk of tracer movement occurred via diffusion between EC. Treatment with cytochalasin B (5 micrograms/ml) resulted in significant AEC and CMEC barrier loss. These results suggest that microfilament bundles are involved in maintaining EC close junctional apposition. We have reported previously that exogenous serotonin and norepinephrine stimulate the EC barrier function in vivo and in vitro, and modulate EC motility, shape, and stress fiber assembly in vitro. In light of these data and the present results, we hypothesize that EC motility and shape change determine in part intercellular macromolecular diffusion by way of a dynamic system of pores of varying radii.

Analysis of Variance↗
PubMed1986

Reduction of polymorphonuclear leukocyte accumulations by inhibition of cyclooxygenase and thromboxane syntase in the rabbit.

Thromboxane (Tx) inhibition prevents pulmonary leukostasis after acid aspiration. This observation prompted study of polymorphonuclear leukocyte (PMN) accumulations and products of cyclooxygenase. Experiments were conducted with a skin abrasion preparation. Five groups of six rabbits were pretreated intravenously with: (1) placebo, (2) ibuprofen, (3) imidazole and two other Tx syntase inhibitors, (4) OKY 1555, or (5) OKY 046. Zymosan-activated serum (ZAS) and leukotriene B4 were used as chemotaxins and balanced salt solution as control. After pretreatment with placebo, PMN accumulation in leukotriene B4 sites was 2130 +/- 874 PMN/mm3 (mean +/- SD). Pretreatment with ibuprofen, imidazole, or OKY 046 decreased (p less than 0.05) accumulations to 205 +/- 139 PMN/mm3, 485 +/- 387 PMN/mm3, and 504 +/- 260 PMN/mm3, respectively. In ZAS sites, placebo pretreatment led to 2006 +/- 866 PMN/mm3, while the ibuprofen, imidazole, and OKY 046 groups had decreased (p less than 0.05) responses of 295 +/- 218 PMN/mm3, 444 +/- 477 PMN/mm3, and 386 +/- 151 PMN/mm3, respectively. Pretreatment with OKY 1555 did not produce significant reductions in response. Six animals in each group received intradermal injections of the two chemotaxins or Hank's balanced salt solution. Reduction in PMN accumulations after cyclooxygenase and Tx inhibition were similar to those observed in the skin abrasion preparation. Pretreatment with either ibuprofen, imidazole, or OKY 046 resulted in a decreased concentration of Tx in abrasion fluid exudate in response to leukotriene B4, 275 +/- 164 pg/ml, 460 +/- 144 pg/ml, and 440 +/- 260 pg/ml, respectively, as compared with 1168 +/- 380 pg/ml in the placebo group. The reduced responses were not the result of a decrease in regional perfusion as measured by 133Xe washout. The in vitro chemotactic response of PMN to leukotriene B4 and ZAS was unchanged after incubation in either ibuprofen, imidazole, OKY 1555, or OKY 046. These data show that cyclooxygenase and Tx syntase are integrally associated with PMN accumulations.

Animals↗
PubMed1986

Nicotine stimulates pulmonary parenchymal thromboxane synthesis.

Smoking increases plasma levels of thromboxane (Tx) B2. Since intravenous nicotine is without effect on platelet TxB2 synthesis, it is likely that lung parenchyma is the site of metabolic importance. This study examines the TxB2 response and functional consequences to the lungs of intratracheal and intravenous instillations of nicotine tartrate. Rat lungs perfused with Krebs-Henseleit (K-H) solution without recirculation were used. After hemodynamic stabilization, the perfusate was either left unaltered or switched to 5 X 10(-4) M nicotine. After 20 minutes of K-H perfusion, effluent levels of TxB2 fell from 41 +/- 6 pg/ml (mean +/- standard error) to 16 +/- 5 pg/ml. A similar decline was noted with nicotine perfusion. K-H perfusion was used throughout the second set of experiments. The lungs were instilled with either saline solution (1 ml/kg body weight) or 5 X 10(-4) M nicotine in saline solution. In the nicotine group, TxB2 levels rose to 86 +/- 5 pg/ml versus 22 +/- 3 pg/ml in saline-instilled controls (p less than 0.05). In addition, pulmonary edema developed in nicotine-instilled lungs. Pretreatment with the Tx synthase inhibitor OKY-046 prevented the rise in TxB2 concentration after nicotine instillation and led to a wet weight/dry weight ratio of 4.0 +/- 0.4 versus 7.5 +/- 1.5 in untreated control lungs (p less than 0.05). Pretreatment with the lipoxygenase inhibitor diethylcarbamazine increased TxB2 levels to 235 +/- 34 pg/ml (p less than 0.05). Diethylcarbamazine also lowered pulmonary artery pressure from 18 +/- 1 mm Hg to 6.1 +/- 0.7 mm Hg in control lungs (p less than 0.05) but did not reduce edema formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Pulmonary and systemic consequences of localized acid aspiration.

Acid aspiration may recruit a generalized inflammatory reaction that can potentiate the local injury. After surgical isolation of bronchi in a group of 15 dogs, 1 milliliter per kilogram of 0.37 normal hydrochloric acid was instilled into either side. After five minutes, platelet and white blood cell counts fell to 10,000 and 1,000 per cubic millimeter (p less than 0.05). Platelet aggregates were noted in blood smears. 111Indium-platelet activity doubled over both the aspirated and nonaspirated lung (p less than 0.05). Physiologic dead space rose from 18 to 67 per cent and to 46 per cent in the aspirated and nonaspirated lung (p less than 0.05). Physiologic shunt increased from 12 to 47 per cent and to 43 per cent (p less than 0.05) on the two sides. Plasma thromboxane B2 levels at 30 minutes rose from 0.28 to 0.93 nanograms per milliliter (p less than 0.05). Edema fluid from the aspirated lung had thromboxane B2 values of 2.87 nanograms per milliliter, indicating pulmonary synthesis. Within five minutes of aspiration, systemic effects were prominent; mean arterial pressure fell from 114 to 46 milliliters of mercury (p less than 0.05), and the cardiac index fell 24 per cent from 106 to 81 milliliters per kilogram per minute (p less than 0.05) along with an 18 per cent decrease in contractility of a rat papillary muscle bathed in plasma from the aspirated dog. Mean pulmonary arterial pressure rose from 12 to 18 millimeters of mercury (p less than 0.05). Despite fluid infusion at 36 milliliters per kilogram per hour to keep wedge pressure constant at 5.5 millimeters of mercury, and sampling of one-third the blood volume, hemoglobin concentration rose 0.9 grams per cent (p less than 0.05) indicating increased microvascular permeability. At autopsy, the aspirated and nonaspirated lung were indistinguishable with congestion, interstitial hemorrhage, and white blood cell infiltrates. Systemic organs showed vascular congestion and edema. These data demonstrate that local aspiration leads to generalized inflammatory sequelae with cardiopulmonary failure.

Animals↗
PubMed1985

Vasoactive amines modulate actin cables (stress fibers) and surface area in cultured bovine endothelium.

Cultured bovine aortic endothelial cells were fixed and stained with NBD-phallicidin and quantitated with a digital image analyzer for changes in actin cables and surface area. Serotonin (5-HT), norepinephrine (NE), dopamine and histamine (all at 10(-4)M concentrations) were tested for their ability to induce cytoskeletal changes. Only 5-HT and NE increased actin cables significantly (p less than 0.01), 80.7% and 97.9%, respectively. Dopamine and histamine treated cells showed a 67.4% and 80.8% decrease in actin cables respectively (p less than 0.01). Stimulated increases of actin cables by 5-HT were inhibited by Ketanserin, and propranolol inhibited NE stimulation of actin cables. Treatment of cells with these blockers alone also decreased actin cables below control values (p less than 0.01). Pretreatment of cells with diphenhydramine, but not cimetidine, inhibited histamine-induced decreases in actin cables. Stimulation of surface area by 5-HT and NE was also observed, with 40.8% and 80.7% increases respectively, when compared with controls (p less than 0.01). The increases in actin cables were associated with a lack of ruffled edges that are indicative of motile cells. In contrast, induced decreases in actin cables resulted in cells with ruffled edges. Exogenous 5-HT and NE have been shown to prevent the increased permeability visible as extravasation of red blood cells from postcapillary venules in thrombocytopenic animals. The present data suggest that 5-HT and NE may be involved in maintaining the endothelial barrier function by a receptor-mediated stimulation of actin cables. Also, histamine-induced decreases in actin cables may be correlated with the amine's action in vivo as a mediator of increased inflammatory permeability.

Actins↗
PubMed1985

Eicosanoid modulation of stress fibers in cultured bovine aortic endothelial cells.

Leukotrienes (LT) B4, LTD4, and thromboxanes (TX) are cytotoxic, and increase microvascular permeability. Because endothelial stress fibers are theorized to be part of the cytoskeletal mechanism by which microvessels maintain their barrier function, the effect of these eicosanoids on stress fibers in bovine aortic endothelial cells was tested. LTB4, LTD4, and TXB2 each decreased stress fiber numbers by 93%, 62%, and 66%, respectively, when compared to controls (P less than 0.01). In contrast, endothelial cells treated with prostacyclin (PGI2) at 10(-7) M, produced a significant increase (P greater than 0.01) in stress fiber numbers, 211% to that of controls. Azaprostanoic acid (13-APA) and FPL55712, receptor antagonists to TX and slow-reacting substance of anaphylaxis (SRS) receptors, respectively, the cyclooxygenase inhibitor ibuprofen, and the TX synthase inhibitors imidazole and ketoconazole were used to test for possible endothelial cell receptor mediation and de novo prostanoid synthesis associated with inflammatory eicosanoid-induced disassembly of stress fibers. Each pharmacologic agent inhibited the LTD4- and TXB2-induced decreases in stress fibers; LTB4-stimulated stress fiber decreases were inhibited only by pretreatment with TX synthase blockers. These data suggest that increased permeability associated with inflammatory eicosanoid metabolites may have as a common target stress fiber disassembly, and the mechanism may be receptor-mediated. That cyclooxygenase and TX synthase blockers inhibited the eicosanoid action suggests that endogenous TX synthesis may be a step in the mechanism. PGI2 enhancement of the microvascular barrier may be related to the effect of PGI2 on promoting stress fiber assembly. In summary, endothelial cell synthesized autocoids derived from arachidonic acid may help to regulate microvascular permeability by way of their action on stress fiber assembly/disassembly, and unbalanced prostanoid secretion by way of LT stimulation may result in a loss of the microvascular barrier and increased permeability.

Actin Cytoskeleton↗