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.

Prostanoid formation during feeding of a preterm formula with long-chain polyunsaturated fatty acids in healthy preterm infants during the first weeks of life.

The objective of this study was to evaluate the effect of conventional and long-chain polyunsaturated fatty acids (LCP)-enriched preterm formula on prostanoid formation in preterm infants during their first weeks of life. In a prospective, randomized, double-blind study, healthy infants received either formula enriched with LCP (n = 10), standard preterm formula (n = 10), or (expressed) breast milk (n = 10). Urine was sampled, and anthropometric measurements were taken at study entry and after the study period of 3 wk. In vivo formation of prostaglandin E2, thromboxane A2, and prostacyclin was evaluated by measuring the urinary excretion of the respective index metabolities by gas chromatography-mass spectrometry. There were no significant differences in urinary prostanoid excretion and anthropometric data between the groups at the end of the study period. We conclude that neither conventional formula nor supplementation of a preterm formula with LCP for a period of 3 wk substantially influence prostanoid formation in healthy preterm infants.

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.

Effect of high-dose etodolac on renal function.

Previous studies from our laboratory have demonstrated transient effects on renal function by etodolac, 200 mg b.i.d. The current study assessed the effects of a larger dose of etodolac (500 mg b.i.d.) to explore the time course of its renal effects and to determine whether the transient effect would become more prolonged with a larger dose. We studied 10 normal subjects and nine patients with renal insufficiency, examining the effects of the first 500 mg dose of etodolac as well as 4 days of b.i.d. administration. In both groups, etodolac transiently decreased fractional excretions of sodium and chloride and urinary prostaglandin E2. In patients, etodolac also transiently decreased inulin and para-aminohippuric acid clearances and urinary 6-keto-prostaglandin F1 alpha. Chronic administration caused no changes in renal function in either group. In summary, in this relatively small group of patients, high-dose etodolac caused only transient, fully reversible effects on renal function, the cumulative effect of which was negligible.

Effect of high-dose ibuprofen on 24-hour blood pressure in healthy women.

The nonsteroidal antiinflammatory drug (NSAID) indomethacin has been shown to increase blood pressure in normotensive individuals. The effect of other NSAID on blood pressure has not been as well studied. We evaluated the effects of ibuprofen, an NSAID currently available without a prescription, on 24-hour ambulatory blood pressure in ten young, healthy, normotensive women. Using a randomized, crossover, double-blind design, subjects received ibuprofen 800 mg and a placebo identical in appearance to ibuprofen three times a day for eight days with a washout period between regimens. Subjects were instructed to follow a no-added salt diet during the study. Twenty-four-hour blood pressure monitoring and 24-hour urine collection for prostaglandin E2, creatinine, and sodium were performed on days 1 and 8 of each study week. Tablet counts and a 40 percent reduction in urinary prostaglandin E2 documented compliance with ibuprofen. Ibuprofen had no significant effect on systolic or diastolic blood pressure at any hour during the 24-hour period. Mean blood pressure for the 24-hour period was 112/73 and 111/73 mm Hg on day 1 and 111/73 and 112/73 mm Hg on day 8 for placebo and ibuprofen, respectively. We conclude that ibuprofen at doses as high as 2400 mg/d for up to seven days has no effect on blood pressure in normotensive women. Further studies are needed in hypertensive subjects.

Alteration of mercuric chloride-induced autoimmune glomerulonephritis in brown-Norway rats by herring oil, evening primrose oil and OKY-046 a selective TXA-synthetase inhibitor.

Repeated subcutaneous (SC) injections of mercuric chloride (MC) in Brown Norway (BN) rats induce an autoimmune glomerulonephritis (GN) due to antiglomerular basement membrane (BM) antibody deposition in the glomeruli. The aim of this study was to investigate the effects on MC-induced autoimmune GN of OKY-046, a selective TXA-synthetase inhibitor herring oil (HO), which is rich in eicosapentaenoic acid (EPA) (5.6%) precursor of the three series of prostaglandins (PGs) and of (inactive) thromboxane (TXA3), and evening primrose oil (EPO), which is rich in linoleic acid (LA) (72%) and gamma-linolenic acid (GLNA) (9%), precursors of the one series of PGs, mainly PGE1, and of (inactive) TXA1. The administration of OKY-046 significantly inhibited proteinuria, partially prevented fibrin thrombi (FT) formation in the glomeruli, decreased urinary TXB, enhanced 6ketoPGF excretion and, increased survival rate of the animals from 60% (group receiving only MC) to 86%. However, OKY-046 did not prevent body weight (BW) loss or the development and deposition of IgG in the glomeruli. Increased intake of HO (80 days prior and throughout the experiment) and avoidance of arachidonic acid (AA) intake produced an effect comparable to that of OKY-046 in the rats. Furthermore, HO significantly inhibited the deposition of IgG in the glomeruli, increased the survival rate of the animals to 100% and further enhanced the increased urinary PGE excretion induced by MC. However, HO did not prevent BW loss in the animals. Increased intake of EPO and avoidance of AA intake produced an effect comparable to that of HO. Additionally, EPO completely prevented BW loss induced by MC in these animals. These findings suggest that the metabolites of AA, EPA and GLNA play an important role either in the development or in the modulation of this model of MC induced GN.

Hypotensive and natriuretic effects of nifedipine in essential hypertension. Role of renal kallikrein-kinin-prostaglandin and renin-angiotensin-aldosterone systems.

To assess the role of renal kallikrein-kinin-prostaglandin and renin-angiotensin-aldosterone systems in the diuretic and natriuretic actions of nifedipine, a calcium-channel blocker, 20 mg of nifedipine was administered orally to 15 patients with essential hypertension. Nifedipine promptly induced a hypotensive effect and an increase in pulse rate. Urine volume, urinary sodium excretion, and creatinine clearance were significantly increased after the administration of nifedipine by 63.5%, 48.5% and 12.4%, respectively. Urinary excretion of kallikrein and prostaglandin E were also significantly increased after the administration of nifedipine by 29.4% and 50.0%, respectively. The change in urinary kallikrein excretion was significantly correlated with that in urine volume (r = 0.70, p less than 0.01) or that in urinary sodium excretion (r = 0.86, p less than 0.01). In addition, the change in urinary prostaglandin E excretion was also significantly correlated with that in urine volume (r = 0.72, p less than 0.01) or that in urinary sodium excretion (r = 0.53, p less than 0.05). Plasma aldosterone concentration did not change despite of the marked increase in plasma renin activity, and plasma aldosterone concentration/plasma renin activity ratio decreased after the administration of nifedipine. These results suggest that the augmented renal kallikrein-kinin-prostaglandin system and the suppressed secretion of aldosterone may be associated with the diuretic and natiuretic action of nifedipine and may contribute to the reduction in blood pressure that is caused mainly by its vasodilatory action.

Urinary excretion of arginine-vasopressin and prostaglandin E2 in essential fatty acid-deficient rats after oral supplementation with unsaturated fatty acid esters.

Essential fatty acid-deficient rats were supplemented with 300 mg/d of pure fatty acid esters: oleate (O), linoleate (L), arachidonate (A), and columbinate (C) for 10 d. The 24-h urine collections from each animal, collected 3 d before supplementations and again the last 3 d of the 10-d supplementation period, were analyzed for volume, and by radioimmunoassay for arginine-vasopressin (AVP) and prostaglandin E2 (PGE2). Linoleate and arachidonate supplements both decreased the initial high urinary AVP excretion, whereas it was further increased by the oleate supplement. There was no effect of columbinate supplementation on urinary AVP excretion. Urinary PGE2 excretion was increased ca. twofold by both linoleate and oleate supplements, increased ca. fivefold by arachidonate supplementation but was unaffected by columbinate supplementation. There was no effect of any of the supplemented fatty acids on urine output. Fatty acid analysis of total kidney lipids revealed a low percentage of 20:3(n-9) in the rats supplemented with (n-6) fatty acid (L, A and C). The triene-tetraene ratio was 1.8 +/- 0.6 (n = 6) in the kidneys of the oleate-supplemented rats. No relationship was found between urinary PGE2 excretion and the percentage of arachidonate or the ratio of 20:3 (n-9)/20:4(n-6) in total kidney lipids. It is suggested that increased urinary AVP excretion in EFA-deficient rats is mainly caused by a change in the renal excretatory mechanism of AVP rather than reflecting an increased plasma AVP concentration. Furthermore it is suggested that renal PGE2 synthesis in vivo is unaffected by high levels of 20:3(n-9) in kidney lipids.

[Characteristics of the water-electrolyte metabolism of hypertension patients with stable hypertension and the principles of diuretic therapy]. / Osobennosti vodno-élektrolitnogo obmena u bol'nykh gipertonicheskoi bolezn'iu so stabil'noi gipertenziei i nekotorye printsipy terapii diuretikami.

Different levels of water-salt metabolism control were studied in patients with stable essential hypertension (SEH). The sample was found to be highly heterogeneous in terms of the magnitude of the body's water-filled spaces in relation to plasma renin activity (PRA) and the cooking salt gustatory sensitivity threshold, examined in the presence of various salt diets and diuretic treatments. Three patterns of response to salt loads were identified in SEH patients with respect to sodium and water elimination by the kidneys: the first was identical to that of normal subjects, while the second one featured increased, and the third one, decreased, diuresis and natriuresis. Prostaglandin E2 and kallikrein were shown to be involved in the formation of the second- and third-type renal response to excessive salt. Differential treatment of EH patients with diuretics alone or, where necessary, in combinations with small-dose beta-blockers or vasodilators provides effective BP control for some 1.5 to 2 years in 65% of patients.

Effects of dietary saturated, N-6 and N-3 polyunsaturated fats on blood pressure and prostaglandins outflow from perfused mesenteric vascular bed in rats.

Effects of the dietary administration of saturated fat and of n-6 and n-3 polyunsaturates on blood pressure, prostaglandin metabolism in small vessels, tissue fatty acid distribution and urinary PGE2 excretion were compared. Rats were divided into three groups. Diets contained 10% hydrogenated coconut oil (HCO), 10% safflower oil (SFO) or 10% cod liver oil (CLO) added to a basic fat free diet for 10 weeks. Systolic blood pressure was increased in the CLO group animals. Urinary PGE2 excretion was decreased in the HCO and CLO groups as compared to that in the SFO group animals. PGE2, 6-keto-PGF1 alpha and thromboxane (Tx) B2 outflow from isolated perfused mesenteric arterial beds were extremely decreased in the CLO group animals, and to a lesser extent in the HCO group as compared to the SFO animals. In the tissue phospholipid, 20:3n-9/20:4n-6 ratios were increased in the HCO group indicating essential fatty acid deficiency, and n-6 and n-3 polyunsaturates were elevated in the SFO and the CLO group animals respectively. Arachidonic acid concentration was highest in the SFO group, while there was no significant differences between the HCO and the CLO group. These results suggest that dietary fatty acid manipulation affects urinary PGE2 excretion and PGI2, PGE2 and TxA2 synthesis in mesenteric arterial beds and also changes the tissue fatty acid distribution. Furthermore, n-3 polyunsaturates caused an extreme reduction of 2-series PGs synthesis in small resistance vessels.

Effect of dietary selenium and injected gold thioglucose on adjuvant-treated rats.

Gold (Au) thioglucose, which has been used in the treatment of rheumatoid arthritis, inhibits selenium (Se)-glutathione peroxidase. Since Au and Se play roles in inflammation, the effects of dietary Se (0, 0.2, and 2.0 ppm for 10 weeks) and injected gold thioglucose (5 mg Au/day/kg body weight for 28 days) in adjuvant-treated rats were investigated. Au toxicity was evidenced by lower body weights and higher tissue weight/body weight ratios for kidneys and spleens of Au-treated rats. Adjuvant-induced inflammation, measured by paw thickness, was not influenced by dietary Se, although Au decreased inflammation in Se-deficient rats. Liver glutathione peroxidase activity was depressed by Se deficiency and by Au. Sulfhydryl levels in liver soluble fraction and plasma were highest for Se-deficient rats. Among liver, kidney, spleen, and plasma, thiobarbituric acid reactants were highest in kidneys of Au-treated rats and lowest in plasma of rats fed 2 ppm Se. gamma-Glutamyltranspeptidase activity in plasma indicated liver damage in Se-deficient rats. Kidney PGE2 output in 24-hour urine samples was unaffected by Au, Se, or adjuvant. Au-Se interactions in vivo are complex, but decreased glutathione peroxidase activity in Au-injected rats suggests that Se nutrition of Au-treated rheumatoid arthritis patients may be a practical concern.

Dihomo-gamma-linolenic acid reverses hypertension induced in rats by diets rich in saturated fat.

This study has shown that hypertension induced in rats by a diet rich in saturated fat (16% coconut oil, 4% palmitic acid by weight) is reversed by the addition of the essential fatty acid, dihomo-gamma-linolenic acid (DHLA), at 5.0% but not at 0.5% of dietary energy. This potent effect of DHLA has been attributed to modulation of prostaglandin biosynthesis.

Effect of dietary depletion and repletion of linoleic acid on renal fatty acid composition and urinary prostaglandin excretion.

To study the effect of dietary modification on urinary prostaglandin E (UPGE) excretion and on renal fatty acid compositions, weanling male rats were raised on a fat-free diet for 6 weeks and were switched to a diet containing 2 energy % of linoleic acid (LA) for 8 days. During fat deprivation, UPGE excretion increased in the first week (6.9 ng/24 hours urine), fell to a minimum of 1.1 ng/24 hours at 3rd week and thereafter remained at a level lower than that in the controls (3.1 ng/24 hours). UPGE excretion returned rapidly to normal (2.7 ng/hr) only 24 hours after LA supplementation. During LA treatment, arachidonic acid (AA) concentrations in renal cholesteryl esters rapidly increased from 19% to 27% (33% in the controls), while concentrations in renal phospholipids (PL) and renal free fatty acids (FFA) did not change during the first four days but reached the normal range at the 8th day. The present studies demonstrate that chronically fat deficient animals excreted significantly less UPGE than that in the controls. However, this deficiency could be rapidly reversed by LA supplementation despite the fact that AA levels in renal lipid fractions remained well below normal. This suggests that dietary LA may be rapidly converted to AA and subsequently to PGE without AA levels rising in the lipid fractions usually thought of as being PG precursors.

Prostaglandin-vasopressin interactions on the renal handling of calcium and magnesium.

The role of prostaglandins in the regulation of sodium and water excretion has been widely studied, but little is known about the influence of prostaglandins (PGs) on the tubular handling of calcium, magnesium or phosphorus. Recent observations have suggested that PGE2 and vasopressin may interact and influence reabsorption of calcium and phosphorus in the cortical collecting duct. The present study investigated the effect of meclofenamate (2 mg/kg), and inhibitor of PG synthesis, on the excretion of calcium, magnesium and phosphorus. Experiments were performed in antidiuretic and water diuretic rats to examine potential PG-vasopressin interactions on the reabsorption of these ions by renal tubules. In antidiuretic rats given meclofenamate, urine osmolality increased whereas urine flow and the fractional excretion of water, urea, sodium, calcium and magnesium decreased by 30 to 50%. In water diuretic animals, urine osmolality and urea excretion were unaltered after meclofenamate administration. Fractional excretion of sodium, water, calcium and magnesium declined approximately 50% in water diuretic rats given meclofenamate. Urinary excretion of PGE2 was not significantly different in water diuretic and antidiuretic rats averaging 262 +/- 78 vs. 167 +/- 35 pg/min, respectively. Meclofenamate significantly reduced urinary excretion of PGE2 in both groups. The results indicate that renal PGs modulate renal tubular reabsorption of calcium and magnesium, as well as sodium and water.

An inhibitory effect of dietary polyunsaturated fatty acids on renin secretion in the isolated perfused rat kidney.

The influence of dietary modification of polyunsaturated fatty acids (PUFA) on renin secretion, renal vascular tone and prostanoid excretion was studied in isolated perfused rat kidneys under basal conditions and in response to angiotensin II. After a four-week regimen of diets enriched with safflower oil, linseed oil or saturated fat, providing 20% of total energy intake (20 energy %), the animals which were fed linseed oil showed a significant fall in the proportion of arachidonic acid in renal phospholipids and a reduction in urinary prostaglandin excretion. In comparison with the other dietary groups, linseed oil feeding also resulted in a consistently lower renal vascular tone with increasing doses of angiotensin II. Under basal conditions both the PUFA-fed groups had significantly lower renal venous renin secretion rates relative to the saturated fat-fed control group. Infusion of angiotensin II (10 ng/min) suppressed renin secretion and abolished significant differences between the groups. As both the control group and the safflower oil group excreted similar levels of urinary prostaglandins, these results suggest that dietary enrichment with 20 energy % PUFA alters renin secretion by a prostaglandin-independent mechanism and that this may contribute to the lower blood pressures observed in these animals compared with the saturated fat-fed control group.

Urinary prostaglandin E2 and vasopressin excretion in essential fatty acid-deficient rats: effect of linolenic acid supplementation.

Three groups of weanling male rats were fed on a fat-free diet for 13 weeks. One group received only the fat-free diet (FF rats), the other 2 groups received the fat-free diet and a daily supplement of 2 energy% ethyl linoleate ([n-6] rats), or 2 energy% ethyl linolenate ([n-3] rats). Urinary excretion of prostaglandin E2 (PGE2), immunoreactive arginine vasopressin (iAVP), and kallikrein were determined. PGE2 was quantitated with a radioimmunoassay having 4.9% cross-reactivity with prostaglandin E3 (PGE3). After 4 weeks on the diet, water consumption and urinary iAVP excretion increased significantly in the FF rats and the (n-3) rats compared with the (n-6) rats. Urinary PGE2 excretion was the same for all 3 groups during the first 10 weeks; thereafter it decreased in FF rats and (n-3) rats compared with the (n-6) rats. There was no difference in urinary PGE2 excretion between the FF rats and the (n-3) rats, even though large differences were found in the percentage of arachidonic acid (20:4[n-6]), icosapentaenoic acid (20:5[n-3]), and icosatrienoic acid (20:3[n-9]) of total kidney fatty acids as well as of kidney phosphatidylinositol fatty acids. Fractionation of urine extracts on high performance liquid chromatography with radioimmunoassay detection indicated that (n-3) rats excreted very little PGE3, if any. Urine output followed the same pattern, as did urinary PGE2 excretion. Urinary kallikrein was estimated at week 12 only. It was found to be significantly lower in FF rats and (n-3) rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Excretion of 6-keto-PGF1 alpha and PGE2 in rats with hereditary hypothalamic diabetes insipidus.

We measured the urinary excretion of a stable metabolite of prostacyclin, 6-keto-PGF1 alpha, and of PGE2 in homozygous Brattleboro rats, a strain with hereditary hypothalamic diabetes insipidus. Excretion of both prostaglandins was largely increased compared to both heterozygous Brattleboro rats and Long-Evans rats. These results are in contrast to previously published observations demonstrating a subnormal excretion of PGE2 in Brattleboro rats. It is suggested that prostaglandin synthesis may be under tonic inhibitory control by vasopressin both in the kidney and in the endothelial cells of blood vessels. The findings further support the view that prostaglandins play an important role in the regulation of water excretion and in the pathogenesis of polyuric conditions.

Augmentation of prostaglandin production by linoleic acid in man.

1. Since several lines of evidence have suggested that a diminution of endogenous prostaglandins (PG) may participate in the pathogenesis of a variety of disease states, it would be advantageous to develop therapeutic approaches that augment endogenous prostaglandin synthesis. Since linoleic acid is readily converted to arachidonic acid, we assessed the effects of linoleic acid administration on immunoassayable PGE and 6-oxo-PGF1 alpha excretion as indices of PGE2 and PGI2 production. 2. Six normal subjects were studied twice: during a seated control study and during an 8 h infusion of a 10% emulsion of safflower oil (Liposyn) containing approx. 77% linoleic acid, in a dose of 1.5 g/kg body weight. 3. Liposyn induced a profound increase in immunoassayable 6-oxo-PGF1 alpha excretion. 4. Simultaneously, immunoassayable PGE excretion increased modestly. 5. The current study raises the possibility that linoleic acid administration might constitute a new therapeutic approach in managing disorders characterized by an impairment of the ability to augment prostaglandin synthesis.