Plasma renin, aldosterone, and urinary prostaglandin E2 levels in children with hypocalcemia due to vitamin D deficiency rickets.

We investigated the effect of hypocalcemia on plasma renin, aldosterone, and urine PGE2 levels in children with vitamin D deficiency rickets (VDDR). In the study group, 25 patients with VDDR-induced hypocalcemia were treated with a single dose of 150,000-300,000 IU cholecalciferol and 50 mg/kg/day elemental Ca for 10 days. On any day between 21th and 30th days after the treatment, the patients' clinical, biochemical and radiologic findings were re-evaluated. The healthy children with the same sex and similar age as the study group comprised the control group. Plasma sodium (Na), potassium (K), calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), parathyroid hormone (PTH), 25- hydroxy vitamin D (25OHD), renin, aldosterone; and urinary Ca, creatinine (Cr) and prostaglandin E2 (PGE2) levels were measured in both the study (pre-treatment and post-treatment) and the control group. Plasma Ca, P, 25OHD and renin levels and urinary PGE2/Cr ratio in the post-treatment group were significantly higher than those in the pre-treatment group while K, ALP, and PTH concentrations were significantly lower. Plasma ALP and PTH levels in pre-treatment group were significantly higher than in the control group while Ca, P, 25OHD, aldosterone and renin concentrations and urinary PGE2/Cr ratio were significantly lower. Post-treatment plasma Ca level was significantly decreased in normal limits compared to the control group while other biochemical parameters were not different from the control group. Plasma Ca concentration was positively correlated with renin level and urinary PGE2/Cr ratio. The findings suggest that hypocalcemia may inhibit the production of renin, aldosterone and PGE2 and a blunt aldosterone secretion may develop even after recovery from hypocalcemia.

Significant increase of prostaglandin E-major urinary metabolite in male smokers: a screening study of age and gender differences using a simple radioimmunoassay.

BACKGROUND: For the assessment of inflammatory status, we have developed a simple, reliable radioimmunoassay (RIA) of prostaglandin E-major urinary metabolite (PGE-MUM), which remains stable in urine after it is metabolized. Using this method, we conducted a screening study to compare standard values of PGE-MUM to serum C-reactive protein (CRP) levels in health check volunteers. METHODS: PGE-MUM (micrograms per gram creatinine) was measured in normal urine samples obtained from 797 samples in volunteers for health check, using a newly developed RIA, and analyzed in relation to age, gender, smoking, and drinking habits. Results were compared to serum CRP. RESULTS: PGE-MUM was significantly higher in males than in females. It was significantly higher in smoking males, compared to males who had never smoked (nonsmokers), particularly in those above 40 years of age. In nonsmokers, PGE-MUM declined in males with advancing age, while it rose in females. Although PGE-MUM reflected current smoking status, independent of smoking index (SI), serum CRP indicated both current and former smoking condition, rather dependent upon SI. CONCLUSIONS: PGE-MUM increases in smokers, as suggested by possible inflammatory injury of pulmonary tissue. This RIA method for PGE-MUM may be thus a sensitive and reliable biomarker for current inflammation, different from serum CRP.

Comparison between Prostaglandin E-major urinary metabolite and C-reactive protein levels to reflect endoscopic scores in patients with ulcerative colitis.

Prostaglandin E-major urinary metabolite (PGE-MUM) and C-reactive protein (CRP) are useful biomarkers in patients with ulcerative colitis. However, whether changes in endoscopic scores over time are reflected in the values of these biomarkers has not been verified. This prospective observational study aimed to assess the relationship between changes in biomarker levels and endoscopic scores in patients with ulcerative colitis. A total of 100 colonoscopy intervals of patients with ulcerative colitis were enrolled. The relationship between variations in the Mayo endoscopic subscore over time and the accompanying changes in biomarker values were investigated. PGE-MUM levels showed a significant rise in the increased endoscopic score group (P = 0.007) and a decrease with reduced endoscopic score group (P = 0.023). CRP levels showed a significant decline with lower endoscopic values (P < 0.001); however, there was no corresponding increase with higher endoscopic scores (P = 0.141). Biomarker levels remained unchanged with stable endoscopic scores (P = 0.090 and P = 0.705). PGE-MUM levels varied significantly, and corresponded to the mucosal healing state (P = 0.019 and P = 0.009). The correlation between changes in PGE-MUM and the endoscopic score was stronger than that for CRP (r = 0.518, P < 0.001 vs. r = 0.444, P < 0.001, respectively). PGE-MUM reflected changes in endoscopic scores more accurately than CRP.

Performance of candidate urinary biomarkers for pancreatic cancer - Correlation with pancreatic cyst malignant progression?

BACKGROUND: Intraductal papillary mucinous neoplasms (IPMN) are precursors of pancreatic cancer. Potential biomarkers of IPMN progression have not been identified in urine. A few urinary biomarkers were reported to be predictive of pancreatic ductal adenocarcinoma (PDAC). Here, we seek to assess their ability to detect high-risk IPMN. METHODS: Urine was collected from patients undergoing pancreatic resection and healthy controls. TIMP-1(Tissue Inhibitor of Metalloproteinase-1), LYVE-1(Lymphatic Vessel Endothelial Receptor 1), and PGEM(Prostaglandin E Metabolite) levels were determined by ELISA and analyzed by Kruskal-Wallis. RESULTS: Median urinary TIMP-1 levels were significantly lower in healthy controls (n = 9; 0.32 ng/mg creatinine) compared to PDAC (n = 13; 1.95) but not significantly different between low/moderate-grade (n = 20; 0.71) and high-grade/invasive IPMN (n = 20; 1.12). No significant difference in urinary LYVE-1 was detected between IPMN low/moderate (n = 16; 0.37 ng/mg creatinine) and high/invasive grades (n = 21; 0.09). Urinary PGEM levels were not significantly different between groups. CONCLUSIONS: Urinary TIMP-1, LYVE-1, and PGEM do not correlate with malignant potential of pancreatic cysts.

Prostaglandin E-major urinary metabolite as a noninvasive surrogate marker for infantile necrotizing enterocolitis.

BACKGROUND: Early definitive diagnosis of necrotizing enterocolitis (NEC) based on Bell's staging criteria is difficult because there are few observable changes on abdominal imaging and blood chemistry tests at the onset of the disease. PURPOSE: To investigate whether prostaglandin E-2 major urinary metabolite (PGE-MUM) can be a useful surrogate marker reflecting the disease state and severity of NEC in infants. METHODS: Infants were enrolled in this study between January 2014 and December 2016. NEC diagnosis was based on Bell's staging criteria > Stage II or necrotic bowel observed at surgery. After diagnosis, PGE-MUM level was measured and compared with that of the other disease and healthy infant groups. RESULTS: Median PGE-MUM value was highest in the NEC group (576 [65-3672] µg/g•Cre/BSA × 1000), followed by the other disease group (94 [57-296] µg/g•Cre/BSA × 1000) and the healthy infant group (19 [10-44] µg/g•Cre/BSA × 1000) (sensitivity: 92.3%, specificity: 81.5%, accuracy: 85.0%; p < 0.01). PGE-MUM level correlated with improved status of NEC, length of necrotic intestine, and Bell's staging criteria. CONCLUSIONS: PGE-MUM level may be a useful surrogate biomarker reflecting the disease state of NEC. The method of urine sample collection is also advantageous, being noninvasive for infants. This is the first study reporting PGE-MUM level in NEC. TYPE OF STUDY: Study of diagnostic test. LEVEL OF EVIDENCE: LEVEL II.

Selective cumulative inhibition of platelet thromboxane production by low-dose aspirin in healthy subjects.

Acetylation of platelet cyclooxygenase by oral aspirin is dose dependent and cumulative with repeated administration. However, no single dose of aspirin has been found to be completely selective of platelet thromboxane (TX) synthesis inhibition in man. We determined the dose dependence, cumulative nature and selectivity of aspirin effects on platelet TXB(2) and renal prostaglandin (PG) and prostacyclin (PGI(2)) production. We measured, by radioimmunoassay, serum TXB(2) levels after whole blood clotting and urinary excretion of PGE(2), PGF(2alpha), and 6-keto-PGF(1alpha), before and after single or repeated oral aspirin doses given to 46 healthy subjects. Single doses of 6-100 mg aspirin resulted in a linear (r = 0.92, P < 0.01) inhibition of platelet TXB(2) production, ranging from 12 to 95% after 24 h. A daily dose of 0.45 mg/kg given for 7 d produced a cumulative and virtually complete inhibition of platelet TXB(2) production, without significantly reducing the urinary excretion of PGE(2), PGF(2alpha), and 6-keto-PGF(1alpha) in both healthy men and women. The platelet inhibitory effect of this regimen was maintained unaltered throughout 1 mo of therapy, with no evidence of cumulative inhibition of renal PG-synthesis. Moreover, furosemide-induced renal PGI(2) synthesis and renin release were unaffected by chronic low-dose aspirin. Following cessation of aspirin therapy, platelet TXB(2) production returned toward control values at a similar rate as after a single higher dose. WE CONCLUDE THAT IN HEALTHY SUBJECTS: (a) aspirin causes a dose-dependent inhibition of platelet TXA(2) production, with no obvious sex-related difference; (b) the inhibitory effect of daily low-dose aspirin is cumulative on platelet TXA(2) but not on renal PG-synthesis; (c) during chronic low-dose aspirin therapy, renal PGI(2)-producing cells are readily activable by furosemide at a time of virtually complete suppression of platelet cyclooxygenase activity.

Attenuation of angiotensin II- and III-induced aldosterone release by prostaglandin synthesis inhibitors.

The effect of two prostaglandin synthesis inhibitors, indomethacin and meclofenamate, on angiotensin II (AII)- and III (AIII)-induced aldosterone release was studied in normal and sodium-depleted conscious rats and in adrenal capsular cell suspensions obtained from normal rats. In normal rats, in vivo AII and AIII were equipotent in causing dose-related increases in serum aldosterone concentrations. Indomethacin decreased the basal serum aldosterone levels by 50% and serum renin levels by 43%. In addition, the steroidogenic effects of AII and AIII were reduced by 45 and 63% with 3 mg/kg of indomethacin and 63 and 73% with 10 mg/kg, respectively. In contrast, meclofenamate failed to alter basal serum levels of aldosterone or AII-stimulated aldosterone release but inhibited serum renin levels by 27% and the aldosterone-stimulating effect of AIII by 99%. Indomethacin (3 mg/kg) and meclofenamate (2 mg/kg) inhibited urinary prostaglandin (PG)E(2) and PGF(2alpha) excretion by 63 and 52% and 37 and 31%, respectively. Both inhibitors significantly decreased the adrenal capsular PGE(2) and PGF(2alpha) content and the conversion of [(14)C]arachidonate to [(14)C]PGE(2) and [(14)C]PGF(2alpha). In sodium-depleted rats, indomethacin produced similar effects reducing the control serum aldosterone levels by 29%, AII-stimulated aldosterone by 47%, and completely suppressing the aldosterone response to AIII without altering serum renin activity. In adrenal cell suspensions, similar results were observed with indomethacin inhibiting basal and AII- and AIII-stimulated aldosterone release by 29, 81, and 93%, respectively. Meclofenamate failed to alter basal and AII-stimulated aldosterone release but inhibited that stimulated by AIII by 86%. The present findings suggest that prostaglandins modulate the effects of the renin-angiotensin system by stimulating the release of renin from the kidney and augmenting the steroidogenic effects of AII and AIII in the adrenal cortex.

Functional significance of renal prostacyclin and thromboxane A2 production in patients with systemic lupus erythematosus.

We have examined the urinary excretion of stable immunoreactive eicosanoids in 23 female patients with systemic lupus erythematosus (SLE), 16 patients with chronic glomerular disease (CGD), and 20 healthy women. SLE patients had significantly higher urinary thromboxane B2 (TXB2) and prostaglandin (PG) E2 excretion and significantly lower 6-keto-PGF1 alpha than did healthy women. In contrast, CGD patients only differed from controls for having reduced 6-keto-PGF1 alpha excretion. The group of SLE patients with active renal lesions differed significantly from the group with inactive lesions for having a lower creatinine clearance and urinary 6-keto-PGF1 alpha and higher urinary TXB2. Higher urinary TXB2 excretion was associated with comparable platelet TXB2 production in whole blood, undetectable TXB2 in peripheral venous blood, and unchanged urinary excretion of 2,3-dinor-TXB2. A significant inverse correlation was found between urinary TXB2 and creatinine clearance rate (CCr). In contrast, the urinary excretion of 6-keto-PGF1 alpha showed a significant linear correlation with both CCr and para-aminohippurate clearance rate (CPAH). In four SLE and seven CGD patients, inhibition of renal cyclooxygenase activity by ibuprofen was associated with a significant reduction in urinary 6-keto-PGF1 alpha and TXB2 and in both CCr and CPAH. However, the average decrease in both clearances was 50% lower in SLE patients than in CGD patients, when fractionated by the reduction in urinary 6-keto-PGF1 alpha or PGE2 excretion. We conclude that the intrarenal synthesis of PGI2 and TXA2 is specifically altered in SLE. Such biochemical alterations are associated with changes in glomerular hemodynamics and may play a role in the progression of SLE nephropathy.

Angiotensin II-induced hypertension in the rat. Effects on the plasma concentration, renal excretion, and tissue release of prostaglandins.

We examined in rats the effects of intraperitoneal angiotensin II (AII) infusion for 12 d on urinary excretion, plasma concentration, and in vitro release of prostaglandin (PG) E2 and 6-keto-PGF1 alpha, a PGI2 metabolite. AII at 200 ng/min increased systolic blood pressure (SBP) progressively from 125 +/- 3 to 170 +/- 9 mmHg (P less than 0.01) and elevated fluid intake and urine volume. Urinary 6-keto-PGF1 alpha excretion increased from 38 +/- 6 to 55 +/- 5 and 51 +/- 7 ng/d (P less than 0.05) on days 8 and 11, respectively, of AII infusion, but urinary PGE2 excretion did not change. Relative to a control value of 129 +/- 12 pg/ml in vehicle-infused (V) rats, arterial plasma 6-keto-PGF1 alpha concentration increased by 133% (P less than 0.01) with AII infusion. Aortic rings from AII-infused rats released more 6-keto-PGF1 alpha (68 +/- 7 ng/mg) during 15-min incubation in Krebs solution than did rings from V rats (40 +/- 3 ng/mg); release of PGE2, which was less than 1% of that of 6-keto-PGF1 alpha, was also increased. Slices of inner renal medulla from AII-infused rats released more 6-keto-PGF1 alpha (14 +/- 1 ng/mg) during incubation than did slices from V rats (8 +/- 1 ng/mg, P less than 0.05), but PGE2 release was not altered. In contrast, AII infusion did not alter release of 6-keto-PGF1 alpha or PGE2 from inferior vena cava segments or from renal cortex slices. Infusion of AII at 125 ng/min also increased SBP, plasma 6-keto-PGF1 alpha concentration, and in vitro release of 6-keto-PGF1 alpha from rings of aorta and renal inner medulla slices; at 75 ng/min AII had no effect. SBP on AII infusion day 11 correlated positively with both 6-keto-PGF1 alpha plasma concentration (r = 0.54) and net aortic ring release (r = 0.70) when data from all rats were combined. We conclude that augmentation of PGI2 production is a feature of AII-induced hypertension. The enhancement of PGI2 production may be an expression of nonspecific alteration in vascular structure and metabolic functions during AII-induced hypertension, as well as the result of a specific effect of the peptide on the arachidonate-prostaglandin system.

Role of renal prostaglandins in sympathetically mediated renin relase in the rat.

Renal prostaglandins (PG) appear to mediate renin release due to stimulation of the intrarenal baroreceptor, but not that due to activation of the macula densa. However, as the role of PG in sympathetically mediated renin release remains unclear, a possible interrelationship between these factors was examined in conscious rats. Hydralazine increased the serum renin levels from 3.1+/-0.8 to 16.7+/-3.0 ng/ml per h at a dose of 1 mg/kg. Indomethacin (5 mg/kg) suppressed urinary PGE(2) and PGF(2alpha) excretion by 89 and 74%, respectively, arachidonate hypotension by 82%, and inhibited the elevated renin levels from hydralazine by 100% without altering the hypotensive effect of the drug. Another PG synthetase inhibitor, meclofenamate, was also effective in attenuating hydralazine-induced renin release, urinary PGE(2) and PGF(2alpha) excretion, and arachidonate hypotension. Isoproterenol, a nonselective beta-adrenergic agonist, increased heart rate, lowered blood pressure, and also stimulated the release of renin when administered intraperitoneally. However, intrarenal infusion of the drug only resulted in increased renin release. Indomethacin inhibited isoproterenol-induced renin release by 66 and 67%, respectively, without altering the hemodynamic effects associated with the intraperitoneal administration of the drug. The selective beta(1) agonist, H133/22, increased the release of renin and heart rate in a dose-related manner without altering blood pressure. H133/22-induced renin release was inhibited by 80% by indomethacin pretreatment. Finally, intrarenal infusions of dibutyryl cyclic AMP (3 mg/kg per min) increased the serum activity from 4.1+/-0.2 to 20.4+/-3.9 ng/ml per h without altering mean arterial pressure. Indomethacin inhibited this renin response to dibutyryl cyclic AMP by 96%. Thus, renal PG appear to be important mediators of sympathetically stimulated renin release acting as a site distal to the beta-adrenergic receptor.

Effects of angiotensin-converting enzyme inhibition on altered renal hemodynamics induced by low protein diet in the rat.

We assessed the role of angiotensin II in mediating the alterations in renal hemodynamics known to result from low protein feeding to normal rats by examining the effect of the angiotensin-converting enzyme (ACE) inhibitor captopril. 2 wk of low protein (6% casein) diet resulted in decreased glomerular filtration rate (normal protein [NP], 1.82 +/- 0.17 vs. low protein [LP], 0.76 +/- 0.01 ml/min; P less than 0.05) and renal plasma flow (NP, 6.7 +/- 0.2 vs. LP, 3.3 +/- 0.3 ml/min; P less than 0.05); renal vascular resistance rose (NP, 8.7 +/- 0.4 vs. LP, 19.8 +/- 1.4 dyn . s per cm5; P less than 0.05). These changes were accompanied by a significant decrease in plasma renin activity (NP, 7.0 +/- 0.7 vs. LP, 4.4 +/- 0.8 ng A I/ml per h; P less than 0.05), plasma aldosterone concentration (NP, 7.0 +/- 0.6 vs. LP, 4.1 +/- 0.7 ng/dl; P less than 0.05), and urinary PGE2 excretion (NP, 3,120 +/- 511 vs. LP, 648 +/- 95 pg/mgCr; P less than 0.05); by contrast renal renin content was significantly increased (NP, 2,587 +/- 273 vs. LP, 7,032 +/- 654 ng A I/mg protein; P less than 0.05). Treatment with captopril (30 mg/kg per d) raised glomerular filtration rate (GFR; LP + capt, 1.6 +/- 0.2 ml/min) and renal plasma flow (RPF; LP + capt, 6.7 +/- 0.7 ml/min), and reduced renal vascular resistance (LP + capt, 9.2 +/- 0.5 dyn/s per cm5) in low protein-fed animals. These values were not different from those measured in untreated and captopril-treated rats fed a normal (23%) protein diet. There were no changes in systemic mean arterial pressure in any group of rats. These data provide evidence that intrarenal angiotensin II mediates the changes in intrarenal hemodynamics induced by protein deprivation. The effects of low protein feeding may be partly potentiated by the reduction in PGE2 synthesis. However, the normalization of GFR and RPF in view of only modest increases in PGE2 excretion after captopril (LP, 648 +/- 95 vs. LP + capt, 1,131 +/- 82 pg/mgCr; P less than 0.05) suggests that if PGE2 is involved in these changes, it plays a permissive but not essential role in the increased renovascular resistance.

Ibuprofen use during extreme exercise: effects on oxidative stress and PGE2.

PURPOSE: Oxidative stress was examined with use (N = 29) or nonuse (N = 25) of ibuprofen in ultramarathoners after the Western States Endurance Run. METHODS: Oxidative stress was assessed by measuring plasma and urinary F2-isoprostanes, plasma nitrite, and plasma urate. A urinary prostaglandin E2 metabolite (PGE-M) was used as an end point to assess ibuprofen use. Ibuprofen users consumed 600 and 1200 mg of ibuprofen the day before and on race day, respectively, and nonusers avoided all antiinflammatory medications. Blood and urine were collected in the morning before the race and immediately after the race. RESULTS: Use compared with nonuse of ibuprofen significantly increased plasma (P

The effects of ivacaftor on CF fatty acid metabolism: An analysis from the GOAL study.

BACKGROUND: Ivacaftor has produced significant improvement in certain individuals with cystic fibrosis (CF), though the full metabolic effects of treatment remain unknown. Abnormalities in fatty acid metabolism have previously been shown to be a characteristic of CFTR dysfunction. We hypothesized that as a reflection of this clinical improvement, ivacaftor would improve plasma fatty acid levels and decrease urine prostaglandin E metabolite levels. METHODS: This study analyzed plasma fatty acid levels and urine prostaglandin E metabolites (PGE-M) in 40 subjects with CF participating in the G551D observational (GOAL) study who demonstrated response to the medication by a significant decrease in sweat Cl levels. Paired samples were analyzed before and after 6months of ivacaftor treatment. RESULTS: Linoleic acid and docosahexaenoic acid levels, which are typically low in individuals with CF, did not significantly increase with ivacaftor treatment. However, arachidonic acid levels did decrease with ivacaftor treatment and there was a significant decrease in the arachidonic acid metabolite PGE-M as measured in the urine [median: before treatment 17.03ng/mg Cr; after treatment 9.06ng/mg Cr; p<0.001]. Furthermore, there were fatty acid age differences observed, including pediatric participants having significantly greater linoleic acid levels at baseline. CONCLUSION: Ivacaftor reduces inflammatory PGE without fully correcting the plasma fatty acid abnormalities of CF. Age-related differences in fatty acid levels were observed, that may be a result of other clinical factors, such as diet, clinical care, or drug response.

Levels of prostaglandin E metabolite, the major urinary metabolite of prostaglandin E2, are increased in smokers.

PURPOSE: Increased levels of cyclooxygenase-2 and prostaglandin E2 (PGE2) have been observed in tobacco-related malignancies of the upper aerodigestive tract. Moreover, exposure to tobacco smoke can stimulate the synthesis of PGE2. Recent evidence suggests that urinary PGE metabolite (PGE-M) can be used as an index of systemic PGE2 production. In this study, we investigated whether levels of urinary PGE-M were increased in smokers and in patients with head and neck squamous cell carcinoma (HNSCC). EXPERIMENTAL DESIGN: Fifty-eight HNSCC cases and 29 age- and gender-matched healthy controls were prospectively enrolled in the study. A detailed smoking history and single void urine specimen were obtained from each participant. Levels of urinary PGE-M were quantified in a blinded fashion using mass spectrometry and compared with smoking history and tumor status. RESULTS: Adjusted for case-control matching, median urinary PGE-M levels were significantly higher in ever smokers (15.7 ng/mg creatinine) compared with never smokers (9.9 ng/mg creatinine) for the entire study population (n = 87, P = 0.005). Concentrations of urinary PGE-M were nearly doubled in ever smokers (15.2 ng/mg creatinine) versus never smokers (7.8 ng/mg creatinine) among healthy controls (P = 0.001). Higher PGE-M levels were observed in current versus former smokers and in those with greater pack-year exposure. A significant difference in amounts of PGE-M was not observed in patients with HNSCC versus healthy controls. CONCLUSIONS: Increased levels of urinary PGE-M were observed in smokers. Urinary PGE-M may have use as a noninvasive biomarker of the effects of tobacco smoke exposure.

Metabolic disposition of prostaglandin E1 in man.

Metabolism of [17, 18-3H]prostaglandin E1 was investigated in three healthy male volunteers during intravenous infusion. The infusion rate was 5.0 ng/kg per min. Blood samples were obtained before the end of the infusion as well as 5, 10, 20, 40, 90 and 180 min afterwards; urine and feces were collected until 96 and 72 h, respectively, after the experiment. All samples were analyzed for radioactivity. Urine was further chromatographed, including by high-pressure liquid chromatography, and subsequently analyzed by gas chromatography-mass spectrometry. Radioactivity in plasma rapidly declined during the first 10 min after termination of the infusion, and then was eliminated exponentially with a mean half-life of 181 min, probably reflecting slow excretion of one or more metabolite. 12% of the administered radioactivity could be recovered from feces and 88% from urine. From the radioactive material obtained from urine the following metabolites could be identified (each number represents data of one volunteer): 7 alpha-hydroxy-5,11-diketotetranor-prostane-1,16-dioic acid (10.4, 20.4 and 30.1%), 7 alpha-hydroxy-5,11-diketotetranor-prostanoic acid (8.2, 6.9 and 9.3%), 5 alpha, 7 alpha-dihydroxy-11-ketotetranor-prostane-1,16-dioic acid and its delta-lactone (together accounting for 4.1, 2.1 and 3.8%).

Prostaglandins E3 and F3 alpha are excreted in human urine after ingestion of n - 3 polyunsaturated fatty acids.

Prostaglandins E3 and F3 alpha, presumably of renal origin, were characterized for the first time in urine of volunteers after ingestion of n - 3 polyunsaturated fatty acids by combined gas chromatography-mass spectrometry. Quantitation of prostaglandins E3, E2, F3 alpha and F2 alpha using deuterated internal standards showed low levels of the 3 series prostaglandins in the control period. Levels of prostaglandins E3 and F3 alpha rose about 10-fold by the 12th week of the dietary trial and were still elevated 4-fold after a wash-out period of 20 weeks. Excretion of prostaglandins E2 and F2 alpha tended to be depressed in the 12th week of the dietary trial and rose again to control values after the wash-out period. Our data indicate that n - 3 polyunsaturated fatty acids are incorporated into the human kidney and are retained there for a long time. Prostaglandins E3 and F3 alpha may contribute to the observed favorable effects of marine oils rich in n - 3 polyunsaturated fatty acids on certain renal diseases.

Identification of the major urinary metabolite of prostaglandin E3 in the rat.

[11,12-3H2]Prostaglandin E3 was administered subcutaneously into male Sprague-Dawley rats in doses of 0.4 microgram-10 mg/kg body weight. 40-60% of the administered radioactivity was excreted in the urine. The major metabolite was isolated by solid phase extraction followed by three steps of high-performance liquid chromatography. The structure of the major metabolite (5-11% of the administered radioactivity) was 7 alpha,11 alpha-dihydroxy-5-ketotetranorprosta-9,13-dienoic acid as shown by gas-liquid chromatography-mass spectrometry and by its conversion into 11 alpha-hydroxy-5-ketotetranorprosta-4(8),9, 13-trienoic acid.

The urinary excretion of prostaglandins E and their corresponding tetranor metabolites by rats fed a diet rich in eicosapentaenoate.

An HPLC method was developed to determine simultaneously in a single analysis prostaglandin E2, prostaglandin E3, tetranor-prostaglandin E1 and delta 17-tetranor-prostaglandin E1 in rat urine. As internal standard omega-nor-prostaglandin E2 was added to the samples at the beginning of the analysis. The assay was applied in feeding experiments in which rats were fed diets with mixtures of (n-6) and (n-3) fatty acids (linoleate, arachidonate, alpha-linolenate and eicosapentaenoate). The level of urinary prostaglandin E2 was not very much affected by the diet and prostaglandin E3 could never be detected in significant amounts. These primary prostaglandins are assumed to reflect prostaglandin biosynthesis in the kidney medulla. Tetranor-prostaglandin E1 is a characteristic urinary metabolite of prostaglandin E2 in the rat; its level increased after feeding arachidonic acid. delta 17-Tetranor-prostaglandin E1 became a major metabolite when the rats received eicosapentaenoic acid. However, we found that the ratio of urinary tetranor-prostaglandin E1/delta 17-tetranor-prostaglandin E1 is not a very reliable measure of the ratio of prostaglandin E2/prostaglandin E3 formed in the body, because prostaglandin E3 is converted to a much greater extent into delta 17-tetranor-prostaglandin E1 than is prostaglandin E2 into tetranor-prostaglandin E1. As a matter of fact, incubations of tissue homogenates of rats resulted always in predominant formation of prostaglandins of the 2-series, even after high eicosapentaenoate diets. We conclude, in agreement with work carried out earlier, that biosynthetic pathways leading to prostaglandins of the 3-series are of minor importance.

Occurrence of prostaglandin E3 in human urine as a result of marine oil ingestion: gas chromatographic-mass spectrometric evidence.

This pilot study is an effort to elucidate the metabolic fate of dietary eicosapentaenoate in vivo and its influence on arachidonate cyclooxygenation at the renal level. The ultimate objective is to shed light on the biochemical mechanisms responsible for the physiologic effects of marine oil on humans. We found prostaglandin E3 (PGE3) in urine of a female volunteer who ingested 10-50 g/day of MaxEPA fish oil concentrate for 4 years. PGE3, a cyclooxygenase metabolite of eicosapentaenoate, could not be detected in 24-h urine pools from the same subject 16 weeks after fish oil supplementation ended. The appearance of PGE3 was concurrent with a reduction of urinary PGE2. Identification of the trienoic prostaglandin was based on comparison of chromatographic behavior of three distinct derivatives of endogenous PGE3 with that of authentic material, and on selected ion monitoring mass spectrometry.