Cross-Reactivity of Δ17-6-Keto-PGF1α with 6-Keto-PGF1α antibodies

The cross-reactivity of the PGI₃ metabolite, Δ17-6-keto-PGF_1α, with antibodies against 6-keto-PGF_1α for radioimmunoassays (RIA) has been investigated. Δ17-6-keto-PGF_1α was obtained either from commercial sources or after its purification from endothelial cells. In the latter case, primary cultured bovine aortic endothelial cells were incubated for 20 min at 37°C with 10 μM eicosapentaenoic acid (EPA) in the presence of 2 μM 13-hydroperoxy-octadecadienoic acid, an activator of the EPA cyclooxygenation, and the 6-keto-PGF_1α and Δ17-6keto-PGF_1α produced were separated by RP-HPLC. Then, cross-reactivities of the commercial and purified Δ17-6-keto-PGF_1α with 6-keto-PGF_1α antibodies were determined and found not to exceed 10%. In addition, the amounts of prostacyclin-related compounds detected by direct measurements in media of cells loaded with EPA were compared with those obtained after purification of 6-keto-PGF_1α. In accordance with the cross-reactivity data, we found that RIA in media mainly measured 6-keto-PGF_1α, the Δ17-6-keto-PGF_1α formed being undetected at 90%. It is concluded that 6-keto-PGF_1α antibodies generally used for RIA of 6-keto-PGF_1α are highly specific since they can discriminate a metabolite bearing an additional double bond such as the PGI₃ metabolite Δ17-6-keto-PGF_1α.     

Changes in urinary 6-keto-prostaglandin F1α excretion during pregnancy and labor

Urinary excretion of 6-keto-PGF_1α was measured by high pressure liquid chromatography and radioimmunoassay at various stages of pregnancy and labor. In the first trimester of pregnancy, urinary 6-keto-PGF_1α concentrations were nor different from those measured before pregnancy, but they showed a significant increase in the second trimester of pregnancy (p <0.001). The levels rose further in the third trimester, although this increase was not statistically significant when compared to levels obtained in the second trimester. There was no evidence for a significance change in 6-keto-PGF_1α excretion with the onset of labor. During well-established, progressive labor mean values of 6-keto-PGF_1α excretion were about twice as high as before the onset of labor, but the range of values during labor was so wide that there was no statistical difference with values obtained in the second half of pregnancy.It is concluded that the increase in the urinary excretion of 6-keto-PGF_1α occurs later in pregnancy than the increase in TXB₂ excretion and that labor at term is not associated with marked changes in 6-keto-PGF_1α excretion.     

6-keto-prostaglandin F1α is not added to urine during passage through the rat urinary bladder

Studies were conducted to determine whether prostaglandins are added to the urine during its passage through the rat urinary blader . Control rats and rats with chronic streptozotocin-induced diabetes were anesthetized with Inactin, 100 mg/kg i.p., and urine was collected simultaneously from both kidneys. Urine from the left kidney was collected directly from the renal pelvis via a ureteral cannula, while urine from the right kidney was collected via a cannula in the urinary bladder. Prostaglandins in the urine were measured by radioimmunoassay. No difference in urinary concentration or rate of excretion of 6-keto-PGF_1α or PGE₂ was seen between ureteral urine and bladder urine from either normal or diabetic rats. The results of this study indicate that there is no intralumenal addition of either 6-keto-PGF_1α or PGE₂ to the urine by the ureteral bladder of rats.     

Facile method for preparation of 2,3-dinor-6-keto PGF1α, the major urinary metabolite of prostacyclin

We report a convenient and efficient method for the preparation of prostaglandin 2,3-dinor-6-keto-F_1α by incubating prostaglandin 6-keto-PGF_1α (6-keto-PGF_1α) with dispersed rat hepatocytes. Chromatographic separation revealed a single product from the hepatocyte metabolism of 6-keto-PGF_1α whose structure was positively confirmed by mass spectrometry as 2,3 dinor-6-keto-PGF_1α. This methods allowed for the preparation of high specific activity radioactive 2,3-dinor-6-keto-PGF_1α which can be utilized to determine the recovery of urinary dinor-6-keto-PGF_1α during extraction and separation of the compound for radioimmunoassay measurements, as well as deuterated 2,3-dinor-6-keto-PGF_1α which can be used as an internal standard in the gas chromatography-mass spectrometric assay of this compound.     

Determination of 6-keto-PGF1α, 2,3-dinor-6-keto-PGF1α, thromboxane B2, 2,3-dinor-thromboxane B2, PGE2, PGD2 and PGF2α in human urine by gas chromatography—negative ion chemical ionization mass spectrometry

A method for quantification of 6-keto-PGF_1α, 2,3-dinor-6-keto-PGF_1α, TXB₂, 2,3-dinor TXB₂, PGE₂, PGD₂ and PGF_2α in human urine samples, using gas chromatography—negative ion chemical ionization mass spectrometry, is described. Deuterated analogues were used as internal standards. Methoximation was carried out in urine samples which were subsequently applied to phenylboronic acid cartridges, reversed-phase cartridges and thin-layer chromatography. The eluents were further derivatized to pentafluorobenzyl ester trimethylsilyl ethers for final quantification by gas chromatography—mass spectrometry. The overall recovery was 77% for tritiated 6-keto-PGF_1α and 55% for tritiated TXB₂. Urinary levels of prostanoids were determined in a group of six volunteers before and after intake of the thromboxane synthase inhibitor Ridogrel, and related to creatinine clearance.     

The pericardium as a source of prostacyclin in the dog, ox and rat

Cyclo-oxygenase products of arachidonic acid metabolism formed by the pericardium and epicardial surface of dog heart were identified and quantitated by radioimmunoassay after separation by high-pressure liquid chromatography. Pieces of pariental pericardium, of dog, ox and rat, when incubated produced mainly 6-keto-PGF_1α, with lesser amounts of PGE₂, PGF_2α and thromboxane B₂. Biosynthesis of all prostanoids increased during incubation of the pariental pericardium of each species with arachidonic acid, but 6-keto-PGF_1α was still the major metabolite. When slices of dog heart were incubated with arachidonic acid (1 μg/ml) the rates of 6-keto-PGF_1α formation by the pariental pericardium was much greater than that of the myocardium and endocardium. Epicardial slices appeared to be intermediate in 6-keto-PGF_1α formation. The hearts of anesthetized dogs were also irrigated with Krebs' solution, and during the first 5 min of epicardial irrigation the pericardial fluid leaving the heart again contained high levels of 6-keto-PGF_1α, with lesser amounts of the other prostanoids. Addition of arachidonic acid (3 μg/ml) to the irrigating fluid caused an increase in all measured prostanoid levels, although 6-keto-PGF_1α remained the predominant metabolite. In contrast, intravenous infusion of isoproterenol selectively increased the release of 6-keto-PGF_1α from the irrigated heart. It is concluded that the pericardium and epicardium continuously release prostacyclin into the pericardial fluid, and that the increased release of this substance observed when cardiac workload increases derives mainly from these membranous sources. This raises the interesting possibility that pericardial prostacyclin might influence coronary vascular tone and chemoreflexes which arise from the epicardium during myocardial ischemia.     

Pulmonary formation of prostacyclin in man

The pulmonary formation of prostacyclin (PGI₂), as reflected by the difference in concentration of pulmonary and systematic arterial radioimmunoassayed 6-keto-PGF_1α, was determined in six healthy waking subjects. The systematic arterial 6-keto-PGF_1α levels were low (50 pg/ml), and no evidence of pulmonary formation and release of the compound was noted. In other experiments systemic arterial 6-keto-PGF_1α levels were determined in patients prior to and during artificial ventilation, as well as during and after occlusion of the pulmonary circulation (extra-corporeal circulation, ECC). The arterial 6-keto-PGF_1α concentration prior to artificial ventillation was 17±4 pg/ml, i.e. within the range observed in the healthy subjects. During artificial ventilation the arterial levels of 6-keto-PGF_1α increased to 191±21 pg/ml, suggesting that pulmonary formation of PGI₂ was stimulated. In the patients subjected to ECC with occluded pulmonary circulation the arterial content of 6-keto-PGF_1α was stabilised at an elevated level (120−170 pg/ml). Following re-establishment of the pulmonary circulation the arterial concentrations of 6-keto-PGF_1α increased markedly, to 284±50 pg/ml. It is suggested that the basal pulmonary formation of PGI₂ in man is low or non-existent, and that enhanced formation of the compound in the lungs is a consequence of intervention with normal pulmonary ventilation or perfusion.     

Analysis of 6-keto-prostaglandin F1 alpha in human urine: age-specific differences

A radioimmunoassay (RIA) for the estimation of 6-keto-PGF1 alpha in human urine is described in detail. The RIA method was validated by direct comparison to gas chromatography-mass spectrometry. In adults and in one year old children basal excretion of 6-keto-PGF1 alpha was found to be lower than that reported for PGE2 or PGF2 alpha. However, during the first week of life, significantly more 6-keto-PGF1 alpha was excreted. The very high levels of 6-keto-PGF in urine seen on the third day of life seemed already to decrease during the first week of life. It is concluded that prostacyclin may have a major role for kidney function in the newborn, possibly by protecting the immature kidney from high levels of angiotensin II.     

Excretion of primary prostanoids and their metabolites during acute volume expansion

Simultaneous determination of urinary excretion rates of primary unmetabolized prostanoids and their enzymatic metabolites were performed by gas chromatography-mass spectrometry (GC/MS) or tandem mass spectrometry (GC/MS/MS). Changes in kidney function were induced by acute (4 h) volume expansion. Despite marked changes in urine flow, GFR, urinary pH, osmolality, sodium and potassium excretion, only a insignificant or transient rise in the enzymatic prostanoid metabolites (2,3-dinor-6-keto-PGF_1α, PGE-M, 2,3-dinor-TxB₂ and 11-dehydro-TxB₂) was observed. The excretion rates of the primary prostanoids were elevated in parallel with the rise in urine flow: PGE₂ rose (p < 0.05) from 14.2 ± 4.0 to 86.2 ± 20.7, PGF_2α from 60.0 ± 4.9 to 119.8 ± 24.0, 6-keto-PGF_2α from 7.2 ± 1.3 to 51.5 ± 17.0, and txB₂ from 11.2 ± 3.3 to 13.6 ± 3.6 ng/h/1.73 m² ( ) at the maximal urine flow. Except for 6-keto-PGF_1α and TxB₂, this rise in urinary prostanoid levels was only transient despite a sustained fourfold elevated urine flow. We conclude that urine flow rate acutely affect urine prostanoid excretion rates, however, over a prolonged peroid of time these effects are not maintained. The present data support the concept that urinary levels of primary prostanoids mainly reflect renal concentrations whereas those of enzymatic metabolites reflect systemic prostanoid activity. From the excretion pattern of TxB₂ one can assume that this prostanoid represents renal as well as systemic TxA₂ activity.     

Prostaglandins and thromboxanes in amniotic fluid during rivanol-induced abortion and labour

Abortion or delivery were induced by extra-amniotic instillation of Rivanol during the second trimester in twelve patients and during the third trimester in two patients with fetal death and one patient with fetal acrania. Serial sampling of amniotic fluid was performed through a transabdominal catheter and the levels of free arachidonic acid (AA), prostaglandin F₂α (PGF₂α), prostaglandin E₂ (PGE₂), 6-keto-prostaglandin F₁α (6-keto-PGF₁α) and thromboxane B₂ (TXB₂) were determined. The levels of AA, PGF₂α, PGE₂, 6-keto-PGF₁α and TXB₂ in amniotic fluid increased significantly during induction with the exception of AA in fetal death which was high and remained constant during induction. Furthermore, PGF₂α, 6-keto-PGF₁α and TXB₂ were all significantly correlated to AA.These observations suggested that free AA is released during Rivanol-induction of abortion and labour giving an increased synthesis of PGF₂α, PGE₂ prostacyclin and thromboxane A₂ in the fetal membranes and the decidua but not in the fetus. This increase might be relevant for the initiation and progress of abortion and labour in these patients.     

Some interrelationships between glucose levels thromboxane production and prostacyclin production in normal and diabetic mice

We investigated the relationship between glucose levels and platelet thromboxane production or aortic prostacyclin production, using radioimmunoassay (RIA) to measure thromboxane B₂ and 6-keto-PGF_2α. We found a direct relationship (p<.05) between plasma glucose levels and thromboxane A₂ production by arachidonate stimulated platelets in platelet rich plasma of normal mice. However, when mice were deprived of food overnight, the glucose level fell but the TxB₂ production rose significantly. Moreover, mice with streptozotocin diabetes had significantly elevated glucose levels. but normal TxB₂ production, which also rose significantly after fasting. Thus in our laboratory both fasting and diabetes nullify or reverse the direct relationship between glucose levels and TxB₂ production seen in normal fed mice. This makes it diffisult to ascribe the correlation between glucose and TxB₂ levels in normal fed animals to cause and effect. RIA revealed an inverse correlation between glucose levels and 6-keto-PGF_1α production which was highly significant in aortas taken from fasted mice and stimulated for 10 minutes with 0.1mM arachidonate. This inverse correlation was present with either normal or diabetic aortas. Moreover, fasting increased the production of 6-keto-PGF_1α. However there was a significant elevation of 6-keto production by aortas of mice with diabetes of 5–6 weeks duration, compared to aortas of normal mice. Therefore either diabetes in these mice reversed a normal inhibitory effect of glucose on 6-keto production, or else the inverse correlation between glucose levels and 6-keto production does not represent a cause and effect relationship between the two variables.     

Simplified assay for the quantification of 2,3-dinor-6-ketoprostaglandin F1α by gas chromatography—mass spectrometry

Endogenous prostacyclin production is best assessed by the measurement of its excreted metabolites, of which a major one is 2,3-dinor-6-ketoprostaglandin F_1α (2,3-dinor-6-keto-PGF_1α). Gas chromatographic—mass spectrometric (GC—MS) assays have been developed for this compound but are cumbersome and time-consuming. We now report a modified assay for the measurement of 2,3-dinor-6-keto-PGF_1α employing GC—MS in which sample preparation time is markedly shortened by replacing a number of extraction steps with reversed-phase column extraction and by modifying derivatization procedures. Precision of the assay is ± 5% and the accuracy is 98%. The lower limit of detection in urine is approximately 15 pg/mg creatinine. Normal urinary levels of this metabolite were found to be 141 ± 54 pg/mg creatinine (mean ± S.D.). Urinary excretion of 2,3-dinor-6-keto-PGF_1α is markedly altered in situations associated with abnormalities of prostacyclin generation when quantified using this assay. Thus, this assay provides a sensitive and accurate method to assess endogenous prostacyclin production and to further explore the role of this compound in human health and disease.     

Prostacyclin induces a surprising long-lasting motility in quiescent uterine strips (indomethacin-treated) isolated from ovariectomized rats

Dose-response curves for several prostaglandins (PGI₂; PGD₂; PGF₂ and PGE₂); BaCl₂ or prostaglandin metabolites (15-keto-PGF_2α; 13, 14-diOH-15-keto-PGF_2α; 6-keto-PGF_1α and 6-keto-PGE₁ in quiescent (indomethacin-treated) uterine strips from ovariectomized rats, were constructed. All PGs tested as well as BaCl₂, triggered at different concentrations, evident phasic contractions. Within the range of concentrations tested the portion of the curves for the metabolites of PGF_2α was shifted to the right of that for PGF_2α itself; the curve for 6-keto-PGF_1α was displaced to the right of the curve for PGI₂ and that for 6-keto-PGE₁ to the left.It was also demonstrated that the uterine motility elicited by 10⁻⁵ M PGF_2α and its metabolites was long lasting (more than 3 hours) and so it was the activity evoked by PGI₂; 6-keto-PGF_1α and BaCl₂, but not the contractions following 6-keto-PGE₁, which disappeared much earlier. The contractile tension after PGF_2α; 15-keto-PGF_2α; 13, 14-diOH-15-keto-PGF_2α and PGI₂, increased as time progressed whilst that evoked by 6-keto-PGF_2α or BaCl₂ fluctuated during the same period around more constant levels.The surprising sustained and gradually increasing contractile activity after a single dose of an unstable prostaglandin such as PGI₂, on the isolated rat uterus rendered quiescent by indomethacin, is discussed in terms of an effect associated to its transformation into more stable metabolites (6-keto-PGF_1α, or another not tested) or as a consequence of a factor which might protects prostacyclin from inactivation.     

Dose-dependent effects of a pyridoquinazoline thromboxane synthetase inhibitor on arachidonic acid metabolites and hemodynamics during E. Coli endotoxemia in anesthetized sheep

We investigated the effects of a new pyridoquinazoline thromboxane synthetase inhibitor infused before administering endotoxin into 18 anesthetized sheep with lung lymph fistulas. In normal sheep increasing plasma Ro 23-3423 concentrations were associated with increased plasma levels of 6-keto-PGF_1α, a reduced systemic vascular resistance (SVR, r = −0.80) and systemic arterial pressure (SAP, r = −0.92), the mean SAP falling from 80 to 50 mm Hg at the 20 and 30 mg/kg doses. Endotoxin infused into normal sheep caused transient pulmonary vasoconstriction associated with increased TxB₂ and 6-keto-PGF_1α levels while vasoconstriction and TxB₂ increase were significantly inhibited by pretreatment with Ro 23-3423 in a dose-dependent manner. When compared to controls, plasma and lymph levels of 6-keto-PGF_1α, PGF_2α and PGE₂ after endotoxin infusion were increased several-fold by administering Ro 23-3423 up to plasma levels of 10 μg/ml. Doses over 30 mg/kg with blood levels above 10 μg/ml reduced plasma and lymph levels of 6-keto-PGF_1α, PGF_2α and PGE₂, suggesting cyclooxygenase blockade at this dose. The peak 6-keto-PGF_1α levels at 60 min after endotoxin infusion in sheep with Ro-23-3423 levels below 10 μg/ml were associated with the greatest systemic hypotension due to a reduced SVR (r = −0.86). After endotoxin infusion the leukotrienes B₄, C₄, D₄ and E₄ in lung lymph were assayed by radioimmunoassay and high pressure liquid chromatography and remained at baseline values.     

Synthesis of thromboxane B2 and 6-keto-prostaglandin F1α by bovine gastric mucosal and muscle microsomes

Bovine gastric mucosal and muscle microsomes synthesize prostaglandins and thromboxane B₂ (TXB₂) from arachidonic acid (AA). TXB₂ and 6-keto-prostaglandin F₁α (6-keto-PGF₁α) were the major products synthesized by pylorus, body, and cardiac region of the gastric mucosa. Gastric muscle mainly synthesized 6-keto-PGF₁α. TXB₂ and 6-keto-PGF₁α synthesis occurs at an appreciable rate from endogenous precursors but more rapidly with added arachidonate. Prostaglandins E₂, F₂α and D₂ were synthesized in smaller amounts under the conditions studied.     

Prostanoids and hemodynamics in man before and during cardiopulmonary bypass

The plasma concentration of 6-keto-PGF_1α, the stable degradation product of prostacyclin, was similar in the radial and pulmonary arteries and in the coronary sinus before and after the induction of the anesthesia in patients undergoing coronary artery bypass surgery. After the beginning of the mechanical ventilation and anesthesia the pulmonary vascular resistance decreased although no changes were detected in the plasma levels of 6-keto-PGF_1α or TXB₂. During the prebypass period after the sternotomy and cannulation of the large vessels the plasma level of 6-keto-PGF_1α was increased similarly in the radial and pulmonary arteries and even more in the coronary sinus. During the cardiopulmonary bypass the concentration of 6-keto-PGF_1α remained at the increased level as compared to the values before the anesthesia. This indicates that pulmonary circulation is perhaps not the main source of prostacyclin in man. The plasma level of TXB₂ was increased during the prebypass period significantly only in the coronary sinus, but during the bypass also in the radial artery. The concentration ratio of 6-keto-PGF_1α/TXB₂ was increased significantly during the prebypass period in the radial and pulmonary arteries. At the same time the pulmonary vascular resistance was, however, returned to the preanesthesia level and was thus not decreased. The vascular resistance in the systemic circulation was increased during the prebypass period. The plasma level of 6-keto-PGF_1α or TXB₂ in the radial and pulmonary arteries did not correlate significantly with the total vascular resistance in the systemic and pulmonary circulation, respectively. The vascular resistance in the coronary circulation did not correlate significantly with TXB₂ level in the radial artery or coronary sinus. There was, however, a slight positive correlation between the blood flow and the concentration of TXB₂ in the coronary sinus (r=0.76, P < 0.01). Coronary sinus flow did, however, not correlate with the plasma level of 6-keto-PGF_1α in the radial artery or coronary sinus. These results indicate that the detected plasma concentrations of prostacyclin and thromboxane A₂ have no significant effects on the total vascular resistance in vivo.     

Sulindac does not preserve renal prostacyclin synthesis during endotoxemia

Previous reports have suggested that sulindac is a unique non- steroidal anti-inflammatory (NSAID) agent, because it does not inhibit renal prostaglandin synthesis in doses that inhibit platelet thromboxane B₂ synthesis when tested . NSAIDS are of potential therapeutic benefit in the treatment of septic or endotoxic shock. Therefore, this study was designed to investigate the proposed unique action of sulindac in experimental endotoxemia. In the current study, the effect of sulindac on aortic, portal and renal venous immunoreactive (i) 6-keto-PGF_1α levels, the stable metabolite of prostacyclin, was investigated during endotoxemia in the rat. In doses sufficient to reduce the elevation in aortic and portal venous plasma 16-keto- PGF_1α levels, sulindac also significantly (p < 0.05) attenuated the elevated renal venous plasma 6-keto-PGF_1α levels, compared to the vehicle group. Using lower doses, sulindac failed to reduce the endotoxin associate increased in either aortic or renal venous plasma 16-keto-PGF_1α levels. Thus, sulindac failed to demonstrate any selective sparing effect on renal prostacyclin generation during endotoxemia.     

Effects of indomethacin, prostaglandin E2, prostaglandin F2α and 6-keto-prostaglandin F1α on hatching of mouse blastocysts

The present study has been performed to investigate how PGs would participate the hatching process. Effects of indomethacin, an antagonist to PGs biosynthesis, on the hatching of mouse blastocysts were examined in vitro. Furthermore, it was studied that prostaglandin E₂ (PGE₂), prostaglandin F_2α (PGF_2α) or 6-keto-prostaglandin F_1α (6-keto-PGF_1α) were added to the culture media with indomethacin. (1) The hatching was inhibited by indomethacin yet the inhibition was reversible. (2) In the groups with indomethacin and PGE₂, no improvement was seen in the inhibition of hatching and the inhibition was irreversible. (3) In the groups with indomethacin and PGF_2α, inhibition of hatching was improved in comparison with the group with indomethacin. (4) In the groups with indomethacin and 6-keto-PGF_1α, no improvement was seen. The above results indicated that PGF_2α possibly had an accelerating effect on hatching and a high concentration of PGE₂ would exert cytotoxic effect on blastocysts.     

Determination of seven prostanoids in 1 ml of urine by gas chromatography—negative ion chemical ionization triple stage quadrupole mass spectrometry

In an isotope dilution assay, prostaglandin (PG) E₂, 6-keto-PGF_1α, thromboxane (Tx) B₂ and their metabolites PGE-M (11α-hydroxy-9,15-dioxo-2,3,4,5,20-pentanor-19-carboxyprostanoic acid), 2,3-dinor-6-keto-PGF_1α, 2,3-dinor-TxB₂ and 11-dehydro-TxB₂ were determined in urine by gas chromatography—triple stage quadrupole mass spectrometry (GC—MS—MS). After addition of deuterated internal standards, the prostaglandins were derivatized to their methoximes and extracted with ethyl acetate—hexane. The sample was further derivatized to the pentafluorobenzylesters and purified by thin-layer chromatography (TLC). Three zones were scraped from the TLC plate. The prostanoid derivatives were converted to their trimethylsilyl ethers and the products were quantified by GC—MS—MS. In each run, two or three prostanoids were determined.     

Hyperglycemia promotes elevated generation of TXA2 in isolated rat uteri

The relationship between high glucose concentrations and arachidonic acid metabolism in uterine tissue from control and diabetic ovariectomized rats was evaluated. Uterine tissue from diabetic rats produced amounts of PGE₂ and PGF_2α similar to controls, while a lower production of 6-keto-PGF_1α (indicating the production of prostacyclin) and a higher production of TXB₂ (indicating the generation of TXA₂) was found in the diabetic group. A group of diabetic rats was treated with phlorizin to diminish plasma glucose levels. Phlorizin treatment did not alter production of PGE₂, PGF_2α, and 6-keto-PGF_1α in the diabetic group. A diminished production of TXB₂ was found in the treated diabetic uteri when compared to the non-treated diabetic group. Moreover, a positive correlation between plasma glucose levels and uterine TXB₂ generation was observed. When control uterine tissue was exposed in vitro to high concentrations of glucose (22 mM) and compared to control tissue incubated in the presence of glucose 11 mM alterations in the generation of PGE₂, PGF_2α, and 6-keto-PGF_1α were not found, but a higher production of TXB₂ was observed and values were similar to those obtained in the diabetic tissue. Alteration in the production of the prostanoids evaluated were not observed when diabetic tissue was incubated in the presence of high concentrations of glucose. These results provide evidence of a direct relationship between plasma glucose levels and uterine production of TXA₂.