6-keto PGF1α Research Articles

The Cerebrospinal Fluid Thromboxane A2 and Prostaglandin I2 Levels in Patients With Severe Head Injury

The aim of this study was to evaluate the levels of thromboxane A2 (TXA2) and prostacyclin (also called prostaglandin I2 or PGI2) production in the ventricular cerebrospinal fluid (CSF) in patients with severe head injury (SHI). CSF samples in the trauma group, which included 15 patients, were obtained via insertion of an intraventricular catheter, and in the control group, which included 5 patients, they were obtained while the patients' shunt procedures were being performed. Levels were measured using the corresponding kits for TXB2 and 6-keto PGF1a metabolites of TXA2 and PGI2, respectively, during the following four periods after trauma: 6 to 10 hours, 20 to 28 hours, 40 to 56 hours, and 64 to 74 hours. CSF concentrations of TXB2 significantly increased in patients with SHI at all times after trauma (P < 0.0001). There was a variation in the levels of 6-keto-PGF1a, however. Between 6 and 10 hours after trauma, a significant decline was noted (P < 0.05). By the first day, levels were markedly increased, on average, three times those found in the controls, but there was a tendency for levels to decline again later. The TXA2/PGI2 ratio was studied, and it remained high, particularly at 6 to 10 hours and 64 to 74 hours after trauma. The ratio revealed the close relation between the severity of injury and a poor Glasgow Outcome Scale score, with the latter being higher in more severe injury. These results suggest that an increased TXA2/PGI2 ratio was closely related to the severity of the brain injury and therefore appears to be an important indicator of secondary brain damage.

Synergistic effect of D-003 and aspirin on experimental thrombosis models

D-003 is a mixture of higher primary aliphatic saturated acids purified from sugarcane wax, with antiplatelet and antithrombotic effects experimentally demonstrated. Octacosanoic acid is the main component of D-003, followed by triacontanoic, dotriacontanoic, and tetracontanoic acids, while other acids are minor components. This work investigates the effects of combination therapy D-003+aspirin (ASA) on arachidonic acid (AA)-induced sudden death in mice and bleeding time in rats. In addition, the effects of D-003 on serum levels of two metabolites of AA: thromboxane A 2 and prostacyclin, assessed through the measurement of their stable metabolites: thromboxane B 2 (TxB 2) and 6 keto PgF1α by radioimmunoassay kits, were also investigated. Combination therapy of D-003 (50 mg/kg) and ASA (3 mg/kg) significantly increased bleeding time in rats in a synergistic manner compared with D-003 or ASA alone. Moreover, the combined treatment of D-003 (200 mg/kg) and ASA (5 mg/kg) in mice protected against AA-induced sudden death (83% survivors) in a synergistic manner which was compared with each treatment alone (33% survivors). These results indicate that antiplatelet effects of D-003 are not mediated by a cyclooxygenase inhibition. D-003 and ASA monotherapies reduced serum TxB 2 levels, whereas D-003, but not ASA, significantly increased 6 keto PgF1α levels.

Evaluation of platelets in heart failure: Is platelet activity related to etiology, functional class, or clinical outcomes?

Abstract Objectives We sought to determine whether platelet activity in patients with heart failure is related to an ischemic versus nonischemic etiologic condition, clinical disease severity, or adverse clinical outcomes. Background Platelet activity may affect outcome in patients with heart failure. A prospective evaluation of the relation of baseline platelet function to etiologic condition, New York Heart Association (NYHA) class, and clinical outcomes has not been previously reported. Methods Ninety-six consecutive outpatients with ambulatory heart failure with an ejection fraction 2 , 6-keto PGF 1α , platelet contractile force, adenosine diphosphate/collagen shear-induced closure time, whole blood aggregation and CD41, CD31, CD62p, and CD51/CD61 by flow cytometry were determined. Survival status and hospitalizations were determined in the heart failure patient cohort. Results The median age of patients was 65 years (22% female, 64% white). An ischemic etiologic condition was present in 61% of patients. The population had mild to moderate heart failure: NYHA class I (1%), II (41%), III (46%), and IV (12.5%) and severe ventricular dysfunction (median ejection fraction=0.20). There were 39 clinical events (7 deaths, 3 cardiac transplants, 29 other first hospitalizations) in 305 median days of observation. Platelet activity, indicated by whole blood aggregation with 5 μmol adenosine diphosphate ( P =.04) and Tx B 2 ( P =.01), was higher in patients with heart failure. Whole blood aggregation was greater than the 90th percentile in 22% of patients with heart failure versus 7% of control subjects. Platelet function did not differ for any of the markers between the ischemic and nonischemic groups and was not affected by antecedent aspirin. There was no relation of NYHA class or the occurrence of events to platelet activity. Conclusion Platelet activity is heightened in 22% of outpatients with stable heart failure symptoms and is not affected by antecedent aspirin therapy. The degree of platelet activation is similar in ischemic and nonischemic patients with heart failure and is not related to clinical disease severity. Current methods to assess platelet activation do not appear to predict outcome. (Am Heart J 2002;143:1068-75.)

Effects of nicotine on thromboxane/prostacyclin balance in myocardial ischemia

It has been proven that nicotine contributes to cardiovascular diseases, although its precise mechanism of action is still unclear. The purpose of this study is to find how nicotine may complicate myocardial ischemia by affecting the thromboxane/prostacyclin (TXA 2/PGI 2) balance. We used four groups ( n=7 each) of isolated and perfused rabbit hearts according to Langendorff method: (i) control group; (ii) group submitted to 1 μM nicotine perfusion during 60 min; (iii) group submitted to a regional ischemia by ligation of the left descending coronary artery during 60 min and (iv) group submitted to nicotine perfusion during ischemia. Levels of TXB 2 and 6-keto PGF 1α, the stable metabolites of TXA 2 and PGI 2 were then determined in the microsomes of the hearts by radioimmunoassay. The results showed that (1) a TXA 2 synthetase activity is present in the myocardium, and this activity, as well as that of PGI 2 synthetase, is decreased by a 60 min ischemia; (2) TXA 2 and PGI 2 activities are not affected by nicotine in the normal myocardium and (3) nicotine infusion during ischemia contributes to the increase of TXA 2/PGI 2 ratio further by decreasing PGI 2. Therefore, these results provide one explanation on how nicotine might worsen myocardial ischemia.

Conjugated linoleic acid exhibits stimulatory and inhibitory effects on prostanoid production in human endothelial cells and platelets

In addition to their reported antitumorigenic properties, various conjugated linoleic acid (CLA) isomers have also been shown to decrease prostanoid synthesis as a result of inhibiting the cyclooxygenase (COX) enzyme. We have previously reported that several CLA isomers inhibited both platelet aggregation and formation of thromboxane A 2 (TXA 2), a proaggregatory and vasoconstrictive agent. Since the interaction between platelets and vascular endothelial cells is essential to maintaining vascular homeostasis, we decided to investigate the effects of various CLA isomers on the production of endothelial prostacyclin (PGI 2), a potent vasodilator and inhibitor of platelet function. Using interleukin 1-β (IL1-β)-stimulated human umbilical vein endothelial cells (HUVECs), we initially established that HUVECs of passage #2 should be used since these cells were most responsive to thrombin-induced conversion of endogenous arachidonic acid to PGI 2, as monitored by the formation of its stable, inactive metabolite, 6-ketoPGF 1α. In the first part of the study, the effects of CLA isomers in the free fatty acid form were tested. The 10( E), 12( Z)- and 9( Z), 11( E)-CLA isomers inhibited thrombin-induced 6-ketoPGF 1α formation with I 50's of 2.6 and 5.5 μM, whereas the 9( Z), 11( Z)- and 9( E), 11( E)-CLA were ineffective at concentrations up to 60 μM. The inhibitory effect of the 10( E), 12( Z)-CLA was irreversible. Next, the effects of CLA incorporation into HUVECs on PGI 2 generation was determined. An average 8-fold stimulation of 6-ketoPGF 1α formation was obtained with quiescent IL1-β-exposed HUVECs pretreated for 18 h with 25 μM 9( Z), 11( Z)-CLA, whereas cells preincubated with the 10( E), 12( Z) isomer enhanced this eicosanoid 3-fold. Such IL1-β-treated HUVECs prelabeled with 25 μM 9( Z), 11( Z)-CLA became refractory to thrombin stimulation, as measured by 6-ketoPGF 1α production, whereas a small, statistically insignificant, inhibition was observed upon thrombin treatment of HUVECs prelabeled with the 10( E), 12( Z) isomer. Qualitative similar results were obtained with resting or thrombin-stimulated platelets containing these esterified CLA isomers indicating that these effects occur with cells that contain either the COX-1 or COX-2 isozymes. The results of this in vitro study indicate that the effects of CLA on cellular prostanoid formation in endothelial cells and platelets can be either inhibitory or stimulatory, and this seems to depend not only on the specific CLA isomer and whether or not the CLA is in the free fatty acid form or esterified into cellular lipids, but also whether cells are in the resting or stimulated state. These findings suggest that in vivo, CLA might have multiple, complex effects on vascular homeostasis.

The Cerebrospinal Fluid Thromboxane A2 And Prostaglandin I2 Levels In Patients With Severe Head Injury

Background: The aim of this study was to evaluate the levels of thromboxane A2 and prostoglandin I2 production in the ventricular cerebrospinal fluid in patients with severe head injury. Methods: CSF samples of the trauma group included 15 patients were obtained from an intraventricular catheter and in control group included 5 patients obtained while their shunt procedures were performing. Levels were measured using the corresponding kits for TXB2 and 6-keto PGF1a, metabolites of TXA2 and PGI2 respectively and CSF concentrations were measured during the following four time periods posttrauma: 6-10, 20-28, 40-56, and 64-74 hours. Results: When compared to the ventricular CSF control values, CSF concentrations of TXB2 were significantly increased in severe head injured-patients at all times post-trauma (p<0.0001). But there was a variation at the levels of 6-keto-PGF1a after trauma. Between 6 to 10 hours following trauma, a significant decline was noted (p<0.05). By the first day, levels were markedly increased, on average, three times those found in the control, but later there was a tendency to decline again. The TXA2/PGI2 ratio was studied. It remained high all times particularly at 6-10, 64,74 hours following trauma and closely related to the severity of injury and poor glasgow outcome score, being higher in more severe injury. Conclusion: These results suggest that, increased TXA2/PGI2 ratio was closely related to the brain injury severity and its outcome and therefore appears to be an important indicator of secondary brain damage. This study was done in Istanbul University, Cerrahpasa Medical School, Department of Neurosurgery

Prostaglandin spectrum in falciparum malaria patients

The prostaglandin (PG) spectrum was studied in falciparum malaria patients. There were three types of classified prostanoid group on observation terms during the recovery period. Group 1 (consists of PGF2α and 9α, 11β-PGF2, 6-keto PGF1α) was not related to the symptom during the recovery process. Group 2 (consists of PGD2, PGE1, PGE2) was also not related; however, it kept a high dose level during the recovery period. Group 3 (consists of TXB2 and 8-epi PGF2α) was shown to be changing towards the recovery period. After the parasite disappeared from the plasma (3 days after the symptoms), TXB2 had increased, and 8-epi PGF2α had decreased. The regeneration and recovery of the platelet might reflect the increase in TXB2. And the high oxidative stress might reflect the 8-epi PGF2α changing.

D-003, a potential antithrombotic compound isolated from sugar cane wax with effects on arachidonic acid metabolites

D-003 is a natural mixture of higher primary saturated aliphatic acids purified from sugar cane wax, whose main component is octacosanoic acid followed by triacontanoic, dotriacontanoic, and tetratriacontanoic acids. D-003 inhibits platelet aggregation and arterial thrombosis experimentally induced in a dose-dependent fashion. This study was undertaken to investigate the effects of D-003 (25 and 200 mg/kg) in experimental models of venous thrombosis and on plasma levels of two metabolites from arachidonic acid (AA) : thromboxane A 2 (TxA 2) and prostacyclin (PgI 2). D-003 orally administered as single doses of 200 mg/kg, but not at 25 mg/kg, significantly increased plasma levels of 6 keto PgF1α levels, a stable metabolite of PgI 2 in PPP obtained from collagen-stimulated blood (4 μg/ml) compared with control group. Nevertheless, levels of 6 keto PgF1α levels determined after 10 days of oral treatment with both doses of D-003 were significantly larger than those of the controls. Likewise, single and repeated oral doses of D-003 (25 and 200 g/kg) significantly reduced the TxB 2 and MDA plasma levels obtained from whole blood stimulated by collagen. Hence, TxB 2/6 keto PgF1α ratio significantly decreased in animals treated with D-003. Single and repeated oral doses of D-003 (25 and 200 mg/kg) significantly reduced the weight of venous thrombus experimentally induced in rats. D-003 at single doses (400 mg/kg but not 200 mg/kg) significantly protected from death induced by endovenous infusion of collagen plus epinephrine in mice. The present results support that these effects of D-003 on AA metabolites could explain, at least partially, its antiplatelet and antithrombotic effects.

Evaluation of platelets in heart failure: Is platelet activity related to etiology, functional class, or clinical outcomes?

Objectives We sought to determine whether platelet activity in patients with heart failure is related to an ischemic versus nonischemic etiologic condition, clinical disease severity, or adverse clinical outcomes. Background Platelet activity may affect outcome in patients with heart failure. A prospective evaluation of the relation of baseline platelet function to etiologic condition, New York Heart Association (NYHA) class, and clinical outcomes has not been previously reported. Methods Ninety-six consecutive outpatients with ambulatory heart failure with an ejection fraction <0.40 and NYHA Class II to IV symptoms who presented to the Duke Heart Failure Clinic and 14 healthy control subjects formed the study groups. Baseline characteristics and blood analyzed for thromboxane (Tx) B2, 6-keto PGF1α, platelet contractile force, adenosine diphosphate/collagen shear-induced closure time, whole blood aggregation and CD41, CD31, CD62p, and CD51/CD61 by flow cytometry were determined. Survival status and hospitalizations were determined in the heart failure patient cohort. Results The median age of patients was 65 years (22% female, 64% white). An ischemic etiologic condition was present in 61% of patients. The population had mild to moderate heart failure: NYHA class I (1%), II (41%), III (46%), and IV (12.5%) and severe ventricular dysfunction (median ejection fraction = 0.20). There were 39 clinical events (7 deaths, 3 cardiac transplants, 29 other first hospitalizations) in 305 median days of observation. Platelet activity, indicated by whole blood aggregation with 5 μmol adenosine diphosphate (P =.04) and Tx B2 (P =.01), was higher in patients with heart failure. Whole blood aggregation was greater than the 90th percentile in 22% of patients with heart failure versus 7% of control subjects. Platelet function did not differ for any of the markers between the ischemic and nonischemic groups and was not affected by antecedent aspirin. There was no relation of NYHA class or the occurrence of events to platelet activity. Conclusion Platelet activity is heightened in 22% of outpatients with stable heart failure symptoms and is not affected by antecedent aspirin therapy. The degree of platelet activation is similar in ischemic and nonischemic patients with heart failure and is not related to clinical disease severity. Current methods to assess platelet activation do not appear to predict outcome. (Am Heart J 2002;143:1068-75.)

Differential regulation of prostacyclin and thromboxane by dexamethasone and celecoxib during oxidative stress in newborn rabbits

To compare the effects of dexamethasone (Dex) and celecoxib (Cel) on F-isoprostane, prostacyclin (PGI 2), and thromboxane A 2 (TxA 2) following hyperoxia, and hyperoxia followed by recovery in room air (RA), newborn rabbits were exposed to hyperoxia (80–100% oxygen) for 4 days, during which they were treated with saline (Sal, i.m.), Dex (i.m.), vehicle (Veh, PO), or Cel (PO, n=12 per group). Six animals in each group were sacrificed immediately following hyperoxia, and the remainder allowed to recover in RA for 5 days. The control litters were treated simultaneously in RA with all conditions other than atmospheric oxygen being identical. Blood samples were assayed for 8-epi-prostaglandin F 2α (8-epi-PGF 2α), 6-keto prostaglandin F 1α (6-ketoPGF 1α), and TxB 2. Dex and Cel decreased 8-epi-PGF 2α during hyperoxia and the recovery period. Dex increased 6-ketoPGF 1α following hyperoxia, while similar increments were noted during recovery with Cel. Although TxB 2 was decreased only during the recovery period, TxB 2/6-ketoPGF 1α ratio was lower during hyperoxia and recovery in both treated groups. The effect of Cel on 8-epi-PGF 2α and TxA 2/PGI 2 ratio confirm the formation of a COX-derived F 2-isoprostane that is possibly linked to TxA 2 receptors. Further studies are required to examine whether Cel can be used as a therapeutic alternative to Dex for oxygen-induced injury in the newborn.

Effect of strenuous arm crank exercise on platelet function in patients with spinal cord injury

Wang J-S, Yang CF, Wong M-K. Effect of strenuous arm crank exercise on platelet function in patients with spinal cord injury. Arch Phys Med Rehabil 2002;83:210-6. Objective: To investigate the effects of arm crank exercise on various platelet functions and prostacyclin in individuals with spinal cord injury (SCI). Design: Case-control study. Setting: Research project at a hospital-based exercise physiology laboratory. Participants: Seven men (with lesions at levels T11, n = 1; T12, n = 2; L1, n = 2; L2, n = 2) and 3 women (T12, n = 1; L1, n = 2) in the SCI group had SCI for at least 6 weeks. Ten age- and gender-matched healthy people who had not engaged in any regular physical activity for at least 1 year were selected as the control group. Intervention: All subjects exercised strenuously by using an arm crank engometer. Main Outcome Measure: Platelet adhesiveness on fibrinogen-coated surface and epinephrine-induced aggregation in vitro, plasma soluble P-selectin (sP-selectin), and urinary 6-keto-prostaglandin F1α (6-keto PGF1α) levels. Results: The SCI group had higher platelet adhesiveness and aggregability and plasma sP-selectin level, but lower urinary 6-keto PGF1α level than the control group. Platelet adhesiveness and aggregability were enhanced by strenuous arm exercise in all subjects, but only in the SCI group was sP-selectin level increased by exercise. Strenuous exercise raised the levels of 6-keto PGF1α in control group subjects, but not in subjects with SCI. Conclusions: Individuals with SCI had more extensive basal and exercise-induced platelet activation and sP-selectin release than people without SCI. Moreover, strenuous arm exercise, which enhanced the release of prostacyclin in healthy subjects, failed to do so in those with SCI. © 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Role of human heme oxygenase-1 in attenuating TNF-alpha-mediated inflammation injury in endothelial cells.

Heme oxygenase (HO) is the rate-limiting enzyme in the formation of bilirubin, an antioxidant, and carbon monoxide (CO), a cell cycle modulator and a vasodilator. Cyclooxygenase (COX) is a hemeprotein that catalyzes the conversion of arachidonic acid (AA) to various prostanoids, which play an important role in the regulation of vascular endothelial function in normal and disease states. The influence of suppression or overexpression of HO isoforms on COX expression and synthesis of prostanoids is of considerable physiological importance. Consequently, the goal of the present study was to determine whether the heme-HO system regulates COX enzyme expression and activity in vascular endothelial cells in the absence and presence of TNF-alpha (100 ng/ml). Endothelial cells stably transfected with the retrovirus containing the human HO-1 gene exhibited a several-fold increase in HO-1 protein levels, which was accompanied by an increase in HO activity and a marked decrease in PGE(2) and 6-keto PGF(1alpha) levels. We also assessed the effect of retrovirus-mediated HO-1 gene transfer in the sense and antisense orientation on HO-1 expression and cell cycle progression in human endothelial cells. The levels of CO and HO activity were increased in cells transduced with the HO-1 sense and were greatly suppressed in cells transduced with HO-1 antisense as compared to control sham-transduced cells (P < 0.05). The percentage of the G(1)-phase in cells transduced with HO-1 significantly increased (41.4% +/- 9.1) compared with control endothelial cells (34.8% +/- 4.9). We measured COX activity by determining the levels of PGI(2) and PGE(2). The levels of PGI(2) decreased in cells transduced with HO-1 sense and increased in cells transduced with HO-1 in antisense orientation. The expression of p27 was also studied and showed a marked decrease in cells transduced with HO-1 sense and a marked increase in the HO-1 antisense transduced cells. Cell cycle analysis of endothelial cell DNA distributions indicated that the TNF-alpha-induced decrease in the proportion of G(1)-phase cells and increase in apoptotic cells in control cultures could be abrogated by transfection with HO-1 in the sense orientation. Tin mesoporphyrin (SnMP) reversed the protective effect of HO-1. These results demonstrate that overexpressing HO-1 mitigated the TNF-alpha-mediated changes in cell cycle progression and apoptosis, perhaps by a decrease in the levels of COX activity.

Obesity is induced in mice heterozygous for cyclooxygenase-2

In mice heterozygous for the cyclooxygenase-2 gene (COX-2 ±) the body weight was enhanced by 33% as compared to homozygous COX-2 − /− mice. The weights of the gonadal fat pads in COX-2 ± mice were enhanced by 3.5 to 4.7 fold as compared to COX-2 − /− mice and by 1.5 to 3.5 fold as compared to wild-type controls +/+. Serum leptin levels and leptin release by cultured adipose tissue of COX-2 ± mice were both elevated as compared to either control or COX-2 − /− animals. The basal release of PGE 2 or 6 keto PGF 1α per fat pad over a 24 h incubation of adipose tissue was reduced by 80% and 95% respectively in tissue from COX-2 − /− mice. NS-398, a specific COX-2 inhibitor, inhibited leptin release by 27% in adipose tissue from control mice, 31% in tissue from COX-1 − /− mice and by 23% in tissue from COX-2 ± mice while having no effect on leptin release by adipose tissue from COX-2 − /− mice. These data indicate that heterozygous COX-2 mice develop obesity which is not secondary to a defect in leptin release by adipose tissue.

Effect of low-dose aspirin in combination with stable fish oil on whole blood production of eicosanoids

The effect of a combination of aspirin and fish oil on eicosanoids was studied. Four subjects were given 37.5 mg aspirin orally, and 6 weeks later they received a natural, stable fish oil daily for 1 week before taking the same single dose of aspirin. Blood samples for determination of whole blood production of eicosanoids were taken before and after each experimental period. Serum thromboxane A2was decreased by 40% (P<0.05) after aspirin alone, but by 62% (P<0.01) after fish oil + aspirin. Serum prostacyclin (measured as 6-keto PGF1a) was decreased by aspirin in both cases. The sum of 6-keto PGF1aand its equipotent fish oil-derived analogue Δ17-6-keto PGF1awas reduced after aspirin intake (55%, NS), but after fish oil + aspirin the reduction was smaller (33%, NS). Leukotriene B4was increased by 19% (P<0.05) after aspirin, and decreased by 69% (P<0.05) after fish oil + aspirin. A combination of stable fish oil and aspirin thus improves the eicosanoid pattern more than aspirin alone.

Gender differences in the attenuation of salt-induced hypertension by angiotensin (1-7)

Chronic infusion of angiotensin (1-7) [Ang-(1-7)] lowers blood pressure in spontaneously hypertensive rats (SHR). To assess the role of Ang-(1-7) in salt-induced hypertension, Ang-(1-7) (24 μg/kg/hr) or saline was administered chronically via osmotic minipump into the jugular vein of 5–6 wk-old male (M) and female (F) Dahl salt-sensitive rats placed on a high-salt (8% NaCl) diet for 2 weeks. Blood pressure (BP) and heart rate were measured prior to the start of the diet and weekly thereafter. Ang-(1-7) significantly attenuated the BP increase after 1 wk on the diet in both M and F rats, but after 2 weeks only in F rats. Enhanced release of prostacyclin, (6-keto PGF 1α), following Ang-(1-7) treatment was observed in both M and F rats. In addition, significant increases in aortic blood flow and plasma levels of nitric oxide were observed in the F rats following Ang-(1-7) treatment. These findings demonstrate that the reduction in BP is due to both prostacyclin and NO and that there is a gender difference in the attenuation of salt-induced hypertension by Ang-(1-7).

Altered release of prostaglandins contributes to hypoxic/ischemic impairment of NOC/oFQ cerebrovasodilation

This study was designed to determine if altered release of prostaglandins contributes to impaired pial artery dilation to the newly described opioid, nociceptin/orphanin FQ (NOC/oFQ), following hypoxia/ischemia in newborn pigs equipped with a closed cranial window. Global cerebral ischemia (20 min) was induced via elevation of intracranial pressure, while hypoxia (10 min) decreased P O 2 to 35±3 mmHg with unchanged P CO 2 . NOC/oFQ (10 −8 and 10 −6 M) modestly increased cerebrospinal fluid (CSF) 6-Keto PGF 1α and TXB 2, the stable breakdown products of PGI 2 and TXA 2, in sham animals (1199±39 to 1704±104 and 299±9 to 409±12 pg/ml for control and 10 −6 M NOC/oFQ 6-Keto PGF 1α and TXB 2, respectively). In 1 h post ischemia/reperfusion (I+R) animals, basal levels of 6-Keto PGF 1α and TXB 2 were elevated. NOC/oFQ-stimulated release of 6-Keto PGF 1α was blocked while such release of TXB 2 was enhanced (526±15 to 822±36 pg/ml for control and 10 −6 M NOC/oFQ CSF TXB 2). Similar, though more pronounced, changes were observed in hypoxia/ischemia/reperfusion (H+I+R) animals. Pretreatment with indomethacin (5 mg/kg i.v.) or SQ 29,548 (10 −4 M), cyclooxygenase and PGH 2/TXA 2 receptor antagonists, partially restored attenuated NOC/oFQ pial artery dilation 1 h after I+R (9±1 and 18±1 vs. 3±1 and 6±1 vs. 8±1 and 13±1% for 10 −8 and 10 −6 M NOC/oFQ in sham, I+R, and I+R — SQ 29,548 pretreated animals). In contrast, NOC/oFQ-induced vasodilation was reversed to vasoconstriction in H+I+R animals and indomethacin or SQ 29,548 similarly partially restored such pial vasodilation. These data indicate that altered stimulated prostaglandin release contributes to hypoxic/ischemic impairment of NOC/oFQ-mediated pial artery dilation.

Evolution of Streptozotocin–Pancreatic Damage in the Rat: Modulatory Effect of Endothelins on the Nitridergic and Prostanoid Pathway

Many lines of evidence indicate that an increased pancreatic production of nitric oxide (NO) and prostaglandins (PGs) is found in the pancreas of streptozotocin-diabetic rats and that endothelins (ETs) are closely related to the nitridergic and prostanoid pathway in several tissues. In the present study the relationship between NO, ETs, and PGs has been explored in isolated pancreatic tissue from streptozotocin-diabetic rats. Pancreatic ET levels are higher in pancreatic tissues from diabetic (D) rats compared to control (C) animals. The addition of nitric oxide synthase (NOS) inhibitors (1 mM NG-nitro-l-arginine methyl ester, 600 μM NG-monomethyl-l-arginine) in the incubating medium reduces and NO donors (SIN-1, 300 μM spermine supress, NONOate 100 μM) increases ET levels in pancreatic slices from C and D animals. PGE2 (10−7 M) increases and indomethacin (10−6 M) decreases ET pancreatic production only in D but not in C tissues when added into the incubating bath. When tissues are incubated in the presence of endothelin 1 (ET-1) (10−7 M), NOS activity is higher in C pancreas, while the ET-receptor antagonist bosentan (B) decreases NOS levels in D but not in C tissues. When pancreatic arachidonic acid (AA) conversion to prostaglandins was explored, ET-1 increased PGF2α, PGE2, and TXB2 levels in C but not in D tissues. B abolishes TXB2 increment due to the diabetic state, but failed in modulating AA conversion to 6-keto PGF1α, PGF2α and PGE2 in D pancreas. Our results show an alteration in AA metabolism, ET production, and NO increment associated with pancreatic damage due to streptozotocin.

Biphasic stimulation of prostacyclin by endogenous nitric oxide (NO) in endothelial cells transfected with inducible NO synthase

Nitric oxide (NO) regulates prostaglandin H synthase (PGHS) activity in various cell types, but reports conflict in regard to its stimulatory versus inhibitory role. Murine lung endothelial cells infected with a retroviral vector expressing the human inducible NO synthase gene were used to prevent ambiguous effects of NO from either exogenous chemical donors or cytokine-stimulated cells. Low concentrations of endogenous NO led to a dose-dependent increase in 6-keto PGF 1α production (p < 0.05), whereas the highest production of NO resulted in lower 6-keto PGF 1α production. These data demonstrate a complex regulation of PGHS activity by NO that needs to be considered when proposing a physiological or pathophysiological role for NO.

Biochemical changes in prostanoids and cerebral expression of cyclooxygenase (COX)-1 and COX-2 during morphine sulfate infusion in the newborn piglet☆

To examine the biochemical regulation of morphine sulfate (MS) on prostanoid synthesis, conscious newborn piglets received a bolus dose of 100 μg/kg followed by a continuous infusion dose of 100 μg/kg/h. The control group received equivalent volume bolus and continuous infusion of 5% dextrose. Blood samples were drawn from the femoral artery and sagittal sinus vein before, during and after infusion for measurement of prostanoids. The expression of mRNAs encoding cyclooxygenases (COX)-1 and -2 in the brainstem, thalamus, cortex, and cerebellum of the newborn piglets were also examined. Systemic PGE 2 levels declined substantially during and post MS infusion ( p < 0.01), whereas sagittal sinus vein PGE 2 levels increased following the bolus dose ( p < 0.01) and at 4 h of continuous infusion ( p < 0.01). MS infusion did not affect systemic 6-ketoPGF 1α levels, however, in the cerebral circulation 6-ketoPGF 1α levels increased 146% ( p < 0.01) following the bolus dose and remained elevated throughout the infusion and post infusion times. Systemic TxB 2 levels increased transiently at 4 h ( p < 0.01) and sagittal sinus vein TxB 2 increased at 0.5 and 1 h ( p < 0.01) during continuous infusion. RT-PCR assays revealed a 1.5- ( p < 0.001) to 4-fold ( p < 0.001) increased expression of COX-1 mRNA in the MS-infused brain samples. In contrast, no differences in COX-2 mRNA were detected between the groups. These data imply that MS may have significant effects on prostanoid synthesis in the newborn. The data further show that the MS-induced prostanoid responses appear to be mediated via COX-1.

Changes in prostacyclin, thromboxane A2 and F2-isoprostanes, and influence of eicosapentaenoic acid and antiplatelet agents in patients with hypertension and hyperlipidemia

Prostacyclin (PGI2), thromboxane A2 (TXA2) and F2-isoprostanes, prostaglandin F2-like compounds, have wide and contrasting spectrum of biological activities and may influence blood pressure and atherogenesis. To investigate the dynamics of PGI2, TXA2 and F2-isoprostanes in patients with hypertension and hyperlipidemia (HH group), we measured the major urinary metabolites of PGI2: 6-keto PGF1α (Keto) and 2,3-dinor-6-keto PGF1α (Dinor), those of TXA2: TXB2 and 11-dehydro TXB2 (Dehydro), and urinary 8-isoprostane (Iso) in 34 patients. Urinary excretion of Dinor was significantly lower in patients than in controls and that of Dehydro was significantly higher in patients than in controls. Keto, TXB2 and Iso were not significantly different between them. Antiplatelet agents decreased not only TXA2 metabolites but also PGI2 metabolites. Urinary C-peptide immunoreactivity was correlated with Dinor and Dehydro. After administration of eicosapentaenoic acid (EPA), total cholesterol (T-cho) and triglycerides (TG) significantly decreased. Although prostanoids did not show significant change, changes in T-cho were correlated with changes in Dinor and changes in Iso. These results suggest that PGI2 and TXA2 of systemic origin might be related to the pathophysiology of hypertension and hyperlipidemia and that the dynamics of PGI2, TXA2 and F2-isoprostanes might be related to not only blood pressure regulation but also lipid and glucose metabolism.