Biomedical subjects

M E Gerritsen

Publications and source records attributed to M E Gerritsen.

At least 73 records · Page 4Linked to original sources

PubMed1991

EDRF released from microvascular endothelial cells dilates arterioles in vivo.

Microvascular endothelial cells (MECs) from rat epididymal fat pad were isolated and cultured in vitro on Cytodex 3 microcarrier beads. In Krebs-suffused cremaster muscle of pentobarbital-anesthetized rats arteriolar diameters (mean control diam 20.9 +/- 0.9 micron) were measured using image shearing video microscopy. Two lines of suffusate (1.5 ml/min each) were established; one contained a column of microcarrier beads only (no cells in line; NC) the other contained a 1-ml column of MECs grown on beads (through cells; TC). The muscle preparation and the MECs were first treated with indomethacin (Indo; 28 microM). Indo treatment blocked arteriolar dilation to A23187 (1 microM) and arachidonic acid (AA; 0.25 microM) administered into the NC line. A 4.0 +/- 0.6 micron increase in arteriolar diameter was observed, however, when A23187 (but not AA) was infused through the TC line containing Indotreated MECs on beads. The A23187-elicited dilation was abolished by the introduction of NG-monomethyl-L-arginine (L-NMMA; 200 microM) into the TC line. Administration of atropine (2 microM) onto the cremaster muscle via the NC line inhibited the dilations in response to acetylcholine (ACh; 2.7 microM) given through the NC line. Infusion of ACh through the TC line onto the atropine-treated cremaster muscle, however, elicited a 5.8 +/- 1.3 micron increase in arteriolar diameter, a response that was blocked by prior administration of L-NMMA into the TC line. Arteriolar dilation induced by adenosine (0.5 microM) or sodium nitroprusside (0.5 microM) applied via the NC or TC line was unaffected by L-NMMA.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗

PubMed1990

Regulation of eicosanoid synthesis in microvessel endothelium: glucocorticoids do not affect arachidonyl CoA synthetase activity.

The properties of acyl coenzyme A (CoA) synthetase activity were characterized in cultured rabbit coronary microvessel endothelial cells. We report here that microvessel endothelial cells contain two long-chain acyl CoA synthetases. One shows activity with a variety of fatty acids, similar to long-chain non-selective fatty acyl CoA synthetases described previously. The other activity was selective for arachidonic acid and other structurally related substrates. Both activities required ATP, Mg2+ and CoA for optimal activity. The arachidonyl CoA and the non-selective acyl CoA synthetases showed different thermolabilities. Arachidonyl CoA formation was inhibited by greater than 50% after 1 min at 45 degrees C, whereas a 15 min heating treatment was necessary to produce the same relative inhibition of oleoyl CoA synthesis. Glucocorticoid pretreatment (10(-7) M dexamethasone) of the RCME cells did not affect the apparent Km or Vmax, nor the fatty acid selectivity for either acyl CoA synthetase. Therefore, although fatty acyl CoA synthetases may be involved in limiting eicosanoid formation, these activities do not appear to be glucocorticoid-responsive.

Adenosine Triphosphate↗

PubMed1990

Dexamethasone increases the release of three 44 kD proteins immunologically related to plasminogen activator inhibitor-1 from human umbilical vein endothelial and rabbit coronary microvessel endothelial cells.

Endothelial cells synthesize and release different proteins involved in their function, and some of these proteins may play important roles in the cellular response to injury, infection, or glucocorticoids. We have examined the profile of proteins released from rabbit coronary microvascular endothelial (RCME) and human umbilical vein endothelial (HUVE) cells using two-dimensional polyacrylamide gel electrophoresis. The production of three anionic 44kD proteins was increased in RCME and HUVE-cell conditioned medium after treatment with dexamethasone, endotoxin or hypoxia-reoxygenation. The three 44 kD proteins were recognized by antisera raised against endothelial type plasminogen activator inhibitor (PAI-1). Dexamethasone treatment of HUVE and RCME cells reduced cellular and secreted plasminogen activator activity, but no significant effect of dexamethasone on PAI-1 activity in conditioned media could be demonstrated. These observations suggest that although the 44Kd proteins exhibit immunoreactivity with PAI-1 antisera, these proteins are most likely inactive forms of PAI-1.

Animals↗

PubMed1990

G-proteins and phospholipase activation in endothelial cells.

ATP stimulates arachidonic acid release and prostaglandin biosynthesis (most likely via phospholipase A2 (PLA2) activation) and phospholipase C (PLC) activation in cultured rabbit coronary microvessel endothelial cells. Pertussis toxin pretreatment inhibits ATP stimulated prostaglandin release, but not ATP stimulated phosphatidylinositol turnover. In contrast, activation of G-proteins with GTP tau S or AlF4- stimulates both prostaglandin synthesis and PLC. These observations suggest that PLC activation by ATP involves a G-protein(s) that is not ADP-ribosylated by pertussis toxin and further, that ATP activation of prostaglandin biosynthesis appears to involve a different, pertussis toxin sensitive, G-protein.

6-Ketoprostaglandin F1 alpha↗

PubMed1990

Repeated antigen inhalation results in a prolonged airway eosinophilia and airway hyperresponsiveness in primates.

The effects of repeated antigen inhalation on airway cellular composition and airway responsiveness were examined in primates. Airway cellular composition was assessed by bronchoalveolar lavage (BAL), and airway responsiveness was measured as the bronchoconstrictor response to cumulative methacholine dose-response determinations over the course of a 10-wk study. Control animals, exposed to repeated vehicle inhalation challenges, were tested in parallel with the antigen-challenged group. Repeated antigen inhalation resulted in a prolonged inflammatory reaction characterized by a large increase in airway eosinophils (3 +/- 1 to 59 +/- 15%, P less than 0.01). Airway eosinophilia was associated with an increase in airway responsiveness as indicated by a leftward shift in the methacholine dose-response curves, an increase in the slope of the dose-response curves, and a decrease in PC100 values (the dose of methacholine required to cause a 100% increase in lung resistance). The number of BAL eosinophils and the level of eosinophil major basic protein in BAL correlated significantly with methacholine PC100 values (r = 0.61, P less than 0.01 and r = 0.64, P less than 0.01, respectively). Histological examination of lung biopsy samples taken at week 10 of the study demonstrated a striking infiltration of eosinophils in the antigen-challenged animals. These results support earlier observations that demonstrated an association between increases in airway eosinophils and increases in airway responsiveness and suggest that eosinophils are involved in the pathogenesis of hyperresponsive airways.

Administration, Inhalation↗

PubMed1990

Simplified methods for consistent and selective culture of bovine retinal endothelial cells and pericytes.

Different matrix components, in combination with various media and serum supplements, were evaluated for their ability to promote selectively the growth of bovine retinal endothelial cells in primary culture. The optimal setting for the selective growth of retinal endothelial cells was a fibronectin/hyaluronic acid matrix, Dulbecco's modified Eagle's medium (DMEM) supplemented with 20% pooled human serum and 100 micrograms/ml heparin. These conditions consistently yielded virtually homogeneous cultures of endothelial cells, assessed using specific endothelial markers. Thus obtained, the retinal endothelial cells could be subcultured and maintained in phenotypically stable long-term serial cultivation. Homogeneous cultures of retinal pericytes were obtained when microvessel isolates were seeded to uncoated or gelatin-coated culture dishes and grown in DMEM supplemented with 20% fetal bovine serum. The retinal pericytes could also be subcultured and cultivated for numerous populations doublings. Additionally, observations from this study suggest that two populations of pericytes may be obtained in culture and distinguished on the basis of their relative size and antigenic properties.

Actins↗

PubMed1989

Agonist-specific role for Na+-H+ antiport in prostaglandin release from microvessel endothelium.

Rabbit coronary microvascular endothelial (RCME) cells synthesize prostaglandin (PG) I2 and PGE2 in response to stimulation with human thrombin, ATP, and the Ca2+ ionophore, A23187. Replacement of extracellular Na+ with choline or N-methylglucamine reduced thrombin-stimulated PG secretion but did not significantly affect either ATP- or A23187-stimulated PG secretion. Pretreatment of RCME cells with Na+ channel or Na+ -Ca2+ exchange blockers did not alter PG release in response to any of these three agonists. Pretreatment of RCME cells with the specific Na+ -H+ antiport blockers 5-(N-ethyl-N-isopropyl)-amiloride (EIPA, 10 microM) and 5-(N,N-hexamethylene)-amiloride (HMA, 0.1 microM) significantly reduced thrombin but not A23187- or ATP-stimulated PG secretion. Studies with the intracellular pH indicator dye 2,7-bis(carboxyethyl)-5(6)-carboxyfluorescein demonstrated thrombin activation of Na+ -H+ antiport, an effect blocked by either HMA or EIPA. Since manipulations known to inhibit Na+ -H+ exchange (EIPA, HMA, replacement of Na+ with choline or N-methylglucamine) reduced thrombin-stimulated RCME cell PG release, we conclude that activation of Na+ -H+ exchange is involved in the coupling of thrombin interaction with RCME cells to subsequent phospholipase activation and PG release.

Adenosine Triphosphate↗

PubMed1989

Dexamethasone effects on microvascular endothelial cell lipid composition.

Previous studies have shown that treatment of cultured rabbit coronary microvessel endothelial (RCME) cells with dexamethasone results in a dose-, time-, and glucocorticoid-dependent inhibition of prostaglandin release. In the present study, the effects of dexamethasone on RCME membrane lipid composition and release of arachidonic acid were examined. This study demonstrated that dexamethasone treatment did not significantly alter the relative distribution of membrane phospholipids but did result in changes of fatty acid composition. There was an increase in saturated and monounsaturated fatty acids and a decrease in polyunsaturated fatty acids. Dexamethasone treatment did not reduce A23187-stimulated arachidonic acid release, despite inhibiting prostaglandin release by 50%. Studies with radiolabeled arachidonic acid suggest that dexamethasone may exert some actions on membrane remodeling, an effect that will require further investigation. Our data strongly suggest that the inhibitory actions of glucocorticoids on prostaglandin release in cultured RCME cells are not the result of a generalized inhibition of arachidonic acid release, and alternate mechanisms must therefore be considered.

Animals↗

PubMed1989

Antigen-coated sepharose beads induce airway eosinophilia and airway hyperresponsiveness in cynomolgus monkeys.

A method of inducing sustained airway eosinophilia and airway hyperresponsiveness in primates has been developed. Our method utilizes a series of intratracheal instillations of Ascaris suum-coated sepharose 4B beads (3 x 10(5] administered once a week for four weeks. Five cynomolgus monkeys (Macaca fascicularis) demonstrating a naturally occurring skin and respiratory sensitivity to Ascaris suum extract were studied. Airway cell composition was measured by bronchoalveolar lavage (BAL), and airway responsiveness was determined as the bronchoconstrictor response to inhaled methacholine. Ascaris suum bead administration resulted in a transient increase in total cells recovered by BAL (2.4 +/- 0.4 to 8.7 +/- 2.5 x 10(5) cells/ml, p less than 0.05) and a selective increase in BAL eosinophils (17 +/- 6 to 916 +/- 158 x 10(3) cells/ml, p less than 0.05). Increases in airway responsiveness were concurrent with the increase in airway eosinophils. These observations show that airway eosinophilia is associated with airway hyperresponsiveness in primates. Furthermore, this new model is a novel experimental system in which the underlying mechanisms in the pathogenesis of airway hyperresponsiveness can be investigated.

Airway Resistance↗

PubMed1989

Arachidonic acid metabolism by cultured bovine corneal endothelial cells.

Pathways of arachidonic acid metabolism were identified in freshly prepared and in cultured bovine corneal endothelial cells. The principal pathway of arachidonic acid metabolism in the bovine corneal endothelial cells appears to be the cyclooxygenase pathway with the resultant synthesis of PGI2, PGF2 alpha and PGE2. At least two of these products, PGI2 and PGF2 alpha, are formed by the enzymatic conversion of the substrate, PGH2. Measurements of endogenous prostaglandin production by radioimmunoassay demonstrated that PGE2 was the major arachidonic acid metabolite released, with smaller amounts of PGF2 alpha and the stable hydrolysis product of PGI2, 6-keto PGF1 alpha. The release of all three prostanoids was significantly increased by the addition of the calcium ionophore (A23187), human thrombin, bradykinin and histamine. Basal and stimulated release of prostaglandins by the corneal endothelium may contribute to the regulation of intraocular pressure and also in the modulation of the corneal response to injury.

Animals↗

PubMed1989

Dexamethasone induces specific proteins in human trabecular meshwork cells.

Previous studies have demonstrated the presence of high-affinity, glucocorticoid-specific receptors in explants of human outflow tissue and in cultured trabecular meshwork. Glucocorticoid-induced responses of scleral fibroblasts and trabecular meshwork cells were evaluated in this study. Incubation of human trabecular meshwork (HTM) and scleral fibroblast (HS) cells with 10(-7) M dexamethasone (DEX) results in a 60% inhibition of prostaglandin production. The effects of glucocorticoid treatment on cellular and secreted proteins using [35S] methionine incorporation were evaluated. Treatment of HTM cells cultured from two normal individuals with DEX induced the expression of [35S] methionine-labelled cellular proteins of 35, 65 and 70 kD, and secreted proteins of 40, 90 and 100 kD. Under the same experimental conditions, a 70 kD molecular weight cellular protein was induced in the HS cells. There were no apparent DEX-induced alterations in HS-secreted proteins. Since a functional common response to glucocorticoid treatment in both HS and HTM cells was inhibition of prostaglandin production, the dexamethasone-induced expression of the 70 kD protein in these cells may be related to this effect. Further studies are required to elucidate specific roles of the steroid-induced proteins in the effects of glucocorticoids on HTM and HS cells.

Cells, Cultured↗

PubMed1988

Glucose starvation is required for insulin stimulation of glucose uptake and metabolism in cultured microvascular endothelial cells.

In the present study we determined the uptake and disposition of glucose in serum-deprived rabbit coronary microvessel endothelial (RCME) cells. RCME cells exhibited stereospecific hexose uptake inhibited by cytochalasin B. Pretreatment of the RCME cells with potassium cyanide or 2,4-dinitrophenol inhibited 2-deoxyglucose uptake but not 3-O-methylglucose transport. A major proportion (30-60%) of the 2-deoxyglucose present in the RCME cells was not phosphorylated. These two observations suggested that the rate-limiting step in the uptake of 2-deoxyglucose was not transport but rather the phosphorylation of 2-deoxyglucose to 2-deoxyglucose 6-phosphate. When glucose-deprived cells were incubated 2 hr with [U-14C]glucose the disposition of the label was as follows: glycogen 60%, acid-soluble fraction 30%, and lipid less than 5%. In contrast glucose-fed cells exhibited lower overall glucose incorporation, and a slightly different disposition: glycogen 45%, acid-soluble fraction 50%, and lipid 5%. Glucose-deprived RCME cells also exhibited greater basal levels of 2-deoxyglucose uptake compared to glucose-fed cells. RCME cells incubated in the absence of glucose and serum for 16 hr exhibited dose-dependent insulin stimulation of hexose uptake and subsequent metabolism to macromolecules (i.e., glycogen and the acid-soluble fraction). Significant effects of insulin were observed with concentrations as low as 2 x 10(-10) M, well within the physiological range. In contrast, cells preincubated in serum-free culture medium containing 5.5 mM glucose did not exhibit insulin-enhanced hexose uptake or glucose metabolism (even at doses as high as 10(-7) M). These studies indicate that the effects of insulin on rabbit coronary microvascular endothelial cell glucose uptake and metabolism require both serum and glucose deprivation.

Animals↗

PubMed1987

Functional heterogeneity of vascular endothelial cells.

This review has highlighted some of the well-described differences in endothelial cells derived from different sites of the vascular tree. In presenting a select group of endothelial properties, there was no intention to imply that these are the only properties of endothelial cells that exhibit heterogeneity. Nonetheless, having described endothelial heterogeneity in regard to a number of defined properties, we are left with persistent questions including: Are these divergent properties of endothelial cells fixed? Alternatively, can we alter the properties of endothelial cells by affecting the signals from the environment? A number of reports strongly suggest that endothelial cells are capable of acquiring new properties. Stewart and Wiley investigated the role of the neural tissue environment on the differentiation of brain capillary endothelial cells. These authors transplanted ectopic sites, i.e. vascular segments of brain from very young quail embryos to chick coeliac cavity, and a quail somites to chick brain ventricles. The distinctive morphology of quail cells provided a cell marker to differentiate host from graft. The results of this study demonstrated that mesenteric or somatic vessels growing into grafted brain developed functional, structural and histochemical features specific for neural capillaries. Conversely, capillaries in mesodermal tissue that had been grafted to the brain were devoid of the neural capillary characteristics, indicating that brain vessels do not form a barrier when they are made to vascularize non-neural tissue. Milici and Carley reported that bovine adrenal capillary cells cultured on plastic exhibited occasional diaphragmed fenestrations and no transendothelial channels. However, if these same cells were cultured on a basement membrane (matrix) laid down by MDCK cells (a canine nephron epithelial cell line), the cells responded by increasing the number of diaphragmed fenestrations and transendothelial channels. This cell culture study supported an earlier whole animal study in which the importance of the epithelium and/or epithelial basal lamina in the maintenance of endothelial ultrastructure was demonstrated in a developmental study of rat intestinal capillaries. In this earlier study, it was noted that epithelial development coincided with the formation of fenestrations by the endothelium. Enzymatic activities of endothelial cells can also be altered by environmental signals. For example, primary cerebral microvascular endothelial cells exhibit barrier features and are enriched in gamma-glutamyl transpeptidase activity, yet rapidly lose the activity when subcultured.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1987

Metabolism of opioid peptides by cerebral microvascular aminopeptidase M.

Aminopeptidase M (EC 3.4.11.2), which can degrade low molecular weight opioid peptides, has been reported in both peripheral vasculature and in the CNS. Thus, we have studied the metabolism of opioid peptides by membrane-bound aminopeptidase M derived from cerebral microvessels of hog and rabbit. Both hog and rabbit microvessels were found to contain membrane-bound aminopeptidase M. At neutral pH, microvessels preferentially degraded low molecular weight opioid peptides by hydrolysis of the N-terminal Tyr1-Gly2 bond. Degradation was inhibited by amastatin (I50 = 0.2 microM) and bestatin (10 microM), but not by a number of other peptidase inhibitors including captopril and phosphoramidon. Rates of degradation were highest for the shorter peptides (Met5- and Leu5-enkephalin) whereas beta-endorphin was nearly completely resistant to N-terminal hydrolysis. Km values for the microvascular aminopeptidase also decreased significantly with increasing peptide length (Km = 91.3 +/- 4.9 and 28.9 +/- 3.5 microM for Met5-enkephalin and Met5-enkephalin-Arg6-Phe7, respectively). Peptides known to be present within or in close proximity to cerebral vessels (e.g., neurotensin and substance P) competitively inhibited enkephalin degradation (Ki = 20.4 +/- 2.5 and 7.9 +/- 1.6 microM, respectively). These data suggest that cerebral microvascular aminopeptidase M may play a role in vivo in modulating peptide-mediated local cerebral blood flow, and in preventing circulating enkephalins from crossing the blood-brain barrier.

Aminopeptidases↗

PubMed1987

Effects of alkylxanthines and calcium antagonists on adenosine uptake by cultured rabbit coronary microvascular endothelium.

Adenosine uptake by cultured rabbit coronary microvascular endothelial cells was studied. Radiolabeled [2-3H]-adenosine, present initially in the extracellular space at 10(-6) mol/l, was incorporated into the cell cultures at a steady rate during 30 s-3 h incubations. Incorporated 3H was found mostly (83%) in adenine nucleotides. Incorporation of [3H]-adenosine was attenuated by an adenosine deaminase inhibitor (EHNA) but only at adenosine concentrations of 10(-5) mol/l or higher. Adenosine transport inhibitors (dipyridamole, nitrobenzylthioinosine) attenuated 3H incorporation. Adenosine uptake was also diminished by certain structural analogues of adenosine (e.g., 2-chloroadenosine), by several alkylxanthine drugs (theophylline, isobutylmethylxanthine, enprofylline and 8-phenyltheophylline), and by certain calcium antagonists (verapamil, nifedipine and trifluoperazine). The mechanisms of actions of these agents on adenosine uptake do not appear to be related to phosphodiesterase inhibition, adenosine receptor antagonism or calcium antagonism. The effects of varying adenosine metabolism may contribute to the pharmacologic actions of these agents.

1-Methyl-3-isobutylxanthine↗

PubMed1987

Eicosanoid production by the coronary microvascular endothelium.

Cultured rabbit coronary microvessel endothelial (RCME) cells have been used as an in vitro model to study the regulation of microvascular endothelial cell prostaglandin (PG) production by hormones, vasoactive drugs, and inflammatory mediators in an environment that can be tightly controlled and that is unaffected by interactions with other cell types, physical stimulation, or alterations in oxygenation. The most potent stimuli for RCME cell PG secretion were substances associated with inflammation, including histamine, interleukin 1, leukotriene D4, fMet-Leu-Phe, interferon-gamma, and exogenous phospholipases. Inhibition of calcium availability by lower [Ca2+]o or by treatment with calcium channel blockers reduced A23187-stimulated PG release but increased PG synthesis from exogenous arachidonic acid (AA). These observations suggest that Ca2+ may regulate several steps in the pathway leading to PG synthesis and release. Elevated intracellular [Ca2+] may, on the one hand, promote PG production by stimulating phospholipase A2 leading to AA release and, on the other hand, limit the magnitude of the response by increasing the rate of AA reacylation. Glucocorticoids reduce PG production by RCME cells via an action that requires new protein and mRNA synthesis and appears to involve the production of an endothelial cell-derived phospholipase inhibitory protein, or "endocortin." Thus, microvascular endothelial cells can both contribute to (by the release of PGs and possibly platelet-activating factor-acether) and limit (by the production of endocortins) the degree of a local inflammatory response in the heart.

Animals↗

PubMed1987

Calcium ionophore (A23187)- and arachidonic acid-stimulated prostaglandin release from microvascular endothelial cells: effects of calcium antagonists and calmodulin inhibitors.

Calcium ionophore (A23187)-stimulated prostaglandin (PG) E2 and I2 (measured as 6-keto PGF1 alpha) release from cultured rabbit coronary microvessel endothelial (RCME) cells in a time- and dose-dependent manner. A23187-stimulated PG release was reduced by the calcium channel blockers nifedipine, verapamil and diltiazem and by the intracellular calcium blocker, 8-(diethylamino)-octyl-3,4,5-trimethoxybenzoate. A23187-stimulated PG release was significantly reduced by lowering the calcium concentration in the buffer to concentrations of 0.2 mM or less. A23187-stimulated 45Ca uptake was not inhibited by nifedipine (0.5 microM), diltiazem (10 micron) or verapamil (50 microM) although these same concentrations of calcium channel blockers significantly inhibited A23187-stimulated PG release. However, these concentrations of calcium blockers did inhibit K+ (10 mM)-valinomycin (5 microM)-stimulated 45Ca uptake, indicating that, although RCME cells probably have voltage-dependent calcium channels and although calcium influx via these channels is blocked by the calcium channel blockers, voltage-dependent calcium influx plays little or no role in A23187-stimulated 45Ca influx and PG release. KCl-valinomycin significantly stimulated PG release, but this increase was not significantly affected by either nifedipine (0.5 microM) or diltiazem (10 microM) despite complete inhibition of KCl-valinomycin-stimulated 45Ca influx. Verapamil (50 microM) exhibited a small but significant suppression of KCl-valinomycin-stimulated PG release. These observations most likely indicate that calcium influx by voltage-dependent calcium channels plays little or no role in the events leading to either A23187- or KCl-valinomycin-stimulated PG release. The calmodulin antagonists, trifluoperazine and calmidazolium, also reduced A23187-stimulated PG release. In vitro studies of porcine pancreatic phospholipase (PL) A2 activity suggested that the inhibitory actions of trifluoperazine, but not the calcium antagonists, may be mediated by direct inhibitory actions on PLA2. Studies with [3H]arachidonic acid (AA)- and [14C]stearic acid-prelabeled RCME cells suggested that A23187 stimulated both PLA2 and PLC activity, leading to the release of AA. Studies with exogenous AA indicated that reducing calcium availability by reducing buffer calcium concentrations resulted in an enhanced conversion of exogenous AA to PGs. RCME cells incubated in nominally calcium-free buffer exhibited a decreased rate of AA incorporation. The observed increase in AA conversion to PGs in low calcium buffer suggests that calcium may stimulate AA uptake and acylation as well as AA release.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1986

Prostaglandin synthesis and release from cultured human trabecular-meshwork cells and scleral fibroblasts.

Human trabecular-meshwork (HTM) cells in culture convert arachidonic acid to two products: PGE2 and 6-keto PGF1 alpha. Prostaglandin PGE2 was the major product of arachidonic-acid metabolism. The synthesis and release of PGE2 and 6-keto PGF1 alpha was inhibited by a 15-min pre-treatment with indomethacin (5 X 10(-6) M) or a 4-24-hr incubation with 10(-7) M dexamethasone. The effects of dexamethasone could be prevented by cycloheximide (0.5 micrograms ml-1), or actinomycin D (2 micrograms ml-1). Prostaglandin E2 synthesis and release by these HTM cells from two different individuals could be stimulated by bradykinin, arachidonic acid and the calcium ionophore, A23187.

6-Ketoprostaglandin F1 alpha↗