Arachidonic acid metabolism, prostaglandins and the kidney

Elevated ALOX12 in renal tissue predicts progression in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the major causes of end-stage renal disease and one of the significant complications of diabetes. This study aims to identify the main differentially expressed genes in DKD from transcriptome sequencing results and analyze their diagnostic value. The present study sequenced db/m mouse and db/db mouse to determine the ALOX12 genetic changes related to DKD. After preliminary validation, ALOX12 levels were significantly elevated in the blood of DKD patients, but not during disease progression. Moreover, urine ALOX12 was increased only in macroalbuminuria patients. Therefore, to visualize the diagnostic efficacy of ALOX12 on the onset and progression of renal injury in DKD, we collected kidney tissue from patients for immunohistochemical staining. ALOX12 was increased in the kidneys of patients with DKD and was more elevated in macroalbuminuria patients. Clinical chemical and pathological data analysis indicated a correlation between ALOX12 protein expression and renal tubule injury. Further immunofluorescence double staining showed that ALOX12 was expressed in both proximal tubules and distal tubules. Finally, the diagnostic value of the identified gene in the progression of DKD was assessed using receiver operating characteristic (ROC) curve analysis. The area under the curve (AUC) value for ALOX12 in the diagnosis of DKD entering the macroalbuminuria stage was 0.736, suggesting that ALOX12 has good diagnostic efficacy. During the development of DKD, the expression levels of ALOX12 in renal tubules were significantly increased and can be used as one of the predictors of the progression to macroalbuminuria in patients with DKD.

Indomethacin abolishes core temperature, but not cardiovascular or renal, responses to lipopolysaccharide in conscious lambs

1. Core temperature (Tc), cardiovascular and renal responses to lipopolysaccharide (LPS), as well as the role of endogenously produced prostaglandins (PG) in influencing these responses, were investigated in the present study in conscious, chronically instrumented lambs. 2. Core temperature, mean arterial pressure, heart rate (HR), renal blood flow (RBF) and several parameters of renal function were measured for 30 min before and for 5 h after intravenous injection of 0.03 μg/kg of the LPS Salmonella abortus equi (n = 9) or saline vehicle (n = 9). 3. After injection of LPS, Tc increased with a latency of 40 min, duration of 130 min and magnitude of 1.5°C. Mean arterial pressure increased within 110 min of LPS injection and then decreased below baseline within 5 h, concomitant with an increase in HR. There was a sustained increase in RBF after LPS injection and a significant increase in urinary flow rate, as well as Na(+) and Cl(-) excretion. 4. To determine the role of PGs in the responses to LPS observed, additional experiments were performed in another group of conscious lambs that had been pretreated with the non-selective cyclo-oxygenase inhibitor indomethacin (10 mg/kg; n = 6). 5. Although indomethacin abolished the Tc response to LPS, it had no significant effect on the cardiovascular and renal responses to LPS. There were no effects of saline vehicle on any of the variables measured. 6. These data provide evidence that, in conscious young lambs, cardiovascular and renal responses to LPS do not appear to be mediated by endogenously produced PGs and that they are independent of pyrogen-induced changes in Tc.

Sodium balance in pregnancy

Sodium is the major cation in the extracellular fluid volume (ECFV) and as such, is the most important determinant of osmolality and of the volume of this fluid compartment. Hence any alteration in the control of body sodium will be reflected by changes in the ECFV, including the maternal plasma volume. There is no doubt that expansion of the plasma volume is a necessary and desirable event during pregnancy, influencing positively both maternal and fetal outcome. Therefore, studies of sodium balance in pregnancy provide important information relevant to both mother and fetus.

Long-Term Renoprotective Effect of Combination Therapy with Prostaglandin E1 and Angiotensin-Converting Enzyme Inhibitor in Patients with Chronic Renal Failure

Angiotensin-converting enzyme inhibitors (ACE-I) have a renoprotective effect in patients with chronic renal failure. Prostaglandins (PGs) have also been shown to ameliorate renal impairment. Although these two have different mechanisms-ACE-I reduces intraglomerular pressure by dilating the efferent arterioles, while it is thought that PGs may increase intraglomerular pressure--coadministration of these drugs may have an additive effect. Administration of a PG with an ACE-I might have an additive effect on chronic renal failure. However, there have been no studies on the efficacy of such a combination therapy. This study was conducted to determine whether combination therapy with PGE1 and an ACE-I might have a long-term benefit on chronic renal failure. Sixty patients with chronic renal disease receiving an ACE-I in advance were assigned to receive an ACE-I alone or an ACE-I plus PGE1. Blood pressure, blood chemistry, urinary protein excretion, and the changes in the reciprocal of serum creatinine (delta1/Cr) were monitored once monthly for an average of 36.5 months. In patients treated only with an ACE-I, the progression of renal failure did not change with time. In contrast, the decline of renal function was significantly reduced with the combination therapy. The renoprotective effect of the combination therapy was not exerted by reduced proteinuria or by decreased blood pressure. PGE1 may reinforce the renoprotective effects of ACE-I to prevent the progression of chronic renal failure.

Chemical mediators of the muscle ergoreflex in chronic heart failure: a putative role for prostaglandins in reflex ventilatory control

BACKGROUND

The overactivity of ergoreceptors (intramuscular afferents sensitive to products of skeletal muscle work) may be responsible for the abnormal responses to exercise and symptoms of exercise intolerance in chronic heart failure (CHF); however, little is known of the chemical nature of the stimuli involved. We investigated biochemical factors (H+, VCO2, VO2, HCO3, K+, phosphate, lactate, PGE2, PGF(1alpha), and bradykinin) potentially involved in ergoreceptor activation.

METHODS AND RESULTS

Sixteen stable patients with CHF (64.9+/-2.7 years, peak VO2 15.8+/-0.7 mL/kg per min) and 10 age-matched controls were studied. The ergoreceptor test involved two 5-minute handgrip exercises. On one occasion, the subjects recovered normally (control recovery), whereas on the other a posthandgrip regional circulatory occlusion was induced in the exercising arm, isolating the stimulation of the ergoreceptor after exercise. The ergoreflex was quantified as the difference in ventilation between the posthandgrip regional circulatory occlusion and the control recovery periods. During the protocol, the local muscular blood effluent concentrations of metabolic mediators were assessed. Patients had an ergoreflex effect on ventilation greater than controls (4.8+/-1.4 versus 0.4+/-0.1 L/min, P<0.01). During the ergoreflex test in patients, the following metabolites were elevated with respect to resting values in comparison with controls: PGE2 (3.7+/-0.7 versus 1.1+/-0.2 pg/mL), PGF(1alpha) (16.2+/-2.8 versus 7.2+/-1.2 pg/mL), and bradykinin (2.1+/-0.3 versus 1.0+/-0.1 pg/mL), P<0.05 for all comparisons. Only the increases in prostaglandins were predictors of the ergoreflex response (r>0.41, P<0.01).

CONCLUSIONS

Although multiple metabolites are concentrated in exercising muscle in CHF, only prostaglandins correlated with ergoreflex activity, suggesting these factors as potential triggers to the exaggerated ergoreflex, which is characteristic of CHF. This may have important implications for novel therapies to improve exercise tolerance.

Effect of ketorolac on renal function after donor nephrectomy

OBJECTIVES

To evaluate the safety of ketorolac, a nonsteroidal anti-inflammatory drug, that is being used more frequently for postoperative analgesia, we performed a detailed analysis of healthy patients undergoing open donor nephrectomy.

METHODS

We conducted a retrospective review of 198 consecutive patients who underwent open living donor nephrectomy between January 1998 and July 2000. We compared patients who were and were not given ketorolac. Regression analysis was used to determine whether any significant interactions were present between ketorolac and donor age, sex, weight, estimated surgical blood loss, or operative time in terms of its effect on renal function. Creatinine clearance was calculated by the Gault-Cockcroft equation.

RESULTS

Among the 83 patients given ketorolac, the mean amount received was 200 mg (range 30 to 360, median 210). No differences were found in the preoperative creatinine clearance between patients who did (118 +/- 29 mL/min) or did not (118 +/- 27 mL/min, P = 0.89) receive ketorolac. Patients who received ketorolac had a slightly lower creatinine clearance on the second postoperative day relative to patients who did not receive ketorolac (66% versus 72% of preoperative calculated creatinine clearance, P = 0.05). However, at a minimum of 3 months postoperatively, the creatinine clearance did not differ between the two groups (70% versus 73%, P = 0.92). Among patients who received ketorolac, no significant association was found between the amount received and renal function at any point tested. In the regression analysis, no significant interactions were found between ketorolac and the clinical variables of age, sex, weight, estimated surgical blood loss, or operative time. Moreover, in an analysis of only the patients who received ketorolac, no significant interactions were found between the amount of ketorolac received and the clinical variables of age, sex, weight, estimated surgical blood loss, or operative time.

CONCLUSIONS

Ketorolac use was not associated with any long-term impairment in renal function when used during the first 2 postoperative days in healthy patients undergoing open donor nephrectomy. Moreover, in the range administered, no subset of patients or maximal ketorolac dose was identified at which ketorolac use was not safe.

Mesangial cells release untransformed prostaglandin H2 as a major prostanoid

BACKGROUND

Prostaglandin H2 (PGH2) is the precursor of the other prostanoids and exhibits a vasoconstricting activity. Glomerular mesangial cells are an important source of vasoactive prostanoids in kidney. Hence, the present investigation focused on the release of untransformed PGH2 by rat glomerular mesangial cells (RGMCs).

METHODS

Synthesis of prostanoid by resting and interleukin-1beta (IL-1beta)-treated (overnight) RGMCs from exogenous or endogenous arachidonic acid (AA) was assessed by high-performance liquid chromtography or enzyme immunoassay, respectively. Cyclo-oxygenase isoforms were determined by Western blotting. Release of untransformed PGH2 from exogenous AA was evaluated in RGMCs and intact glomeruli as the difference of PGF2alpha formed in the incubations performed in the presence and in the absence of SnCl2 or measuring the ability of aspirin-treated platelets to form thromboxane B2 (TXB2) in mixed incubations of platelets and RGMCs or glomeruli.

RESULTS

The prostanoids formed by RGMCs were PGE2, PGF2alpha, PGI2 and PGD2. SnCl2 totally deviated formation of PGE2 and PGD2 toward PGF2alpha in resting RGMCs, whereas PGE2 was only partially deviated toward PGF2alpha in IL-1beta-treated RGMCs. The PGE2/PGD2 ratio in resting RGMCs was similar to that expected for nonenzymatic isomerization of PGH2, whereas this ratio was higher in IL-1beta-treated RGMCs, suggesting the induction of PGE synthase by IL-1beta. Aspirin-treated platelets formed TXB2 when either RGMCs or intact glomeruli were present in the incubation and formation of TXB2 was approximately fourfold higher with IL-1beta-treated RGMCs or glomeruli.

CONCLUSIONS

RGMCs and intact glomeruli released substantial amounts of untransformed PGH2, which was enhanced following exposure to IL-1beta.

New pharmacologic options for renal preservation

The understanding of the cause and pathophysiology of renal failure has guided the rational development of pharmacologic renoprotective strategies. Although traditionally anesthesiologists have focused on renal hemodynamic derangements, newer information suggests that cellular interactions amplify and perpetuate the insult. Consequently, the potential renoprotective armamentarium not only encompasses the more traditional vasoactive agents but also therapeutic approaches that may modify the cellular response to injury. Although few of these agents have reached the clinical arena, preliminary work suggests that this new approach to renal injury and protection may be promising.

Renal blood flow regulation, autoregulation, and vasomotor nephropathy

Renal blood flow and renal perfusion pressure are regulated by two control mechanisms. The first, extrinsic, actually involves a complex interaction of vasomotor effects between opposing neurohormonal systems. The second, intrinsic mechanism, renal autoregulation, depends on changes in afferent arteriolar tone in response to the renal perfusion pressure itself. This article reviews these two mechanisms, how they normally respond to stress, and the clinical implications of certain situations in which these control mechanisms are disrupted.

Urinary prostaglandin excretion in pregnancy: the effect of dietary sodium restriction

INTRODUCTION

Dietary sodium restriction results in activation of the renin-angiotensin-aldosterone-system. In the non-pregnant situation renin release in response to a low sodium diet is mediated by prostaglandins. We studied the effect of dietary sodium restriction on urinary prostaglandin metabolism in pregnancy.

PATIENTS AND METHODS

In a randomized, longitudinal study the excretion of urinary metabolites of prostacyclin (6-keto-PGF(1 alpha)and 2,3-dinor-6-keto-PGF(1 alpha)) and thromboxane A(2)(TxB(2)and 2,3-dinor-TxB(2)) was determined throughout pregnancy and post partum in 12 women on a low sodium diet and in 12 controls.

RESULTS

In pregnancy the excretion of all urinary prostaglandins is increased. The 6-keto-PGF(1 alpha)/ TxB(2)-ratio as well as the 2, 3-dinor-6-keto-PGF(1 alpha)/ 2,3-dinor-TxB(2)-ratio did not significantly change in pregnancy. CONCLUISION Prostacyclin and thromboxane do not seem to play an important role in sodium balance during pregnancy.

Effects of tetrodotoxin and OKY-046 in renal ischemia reperfusion

Ischemia reperfusion injury (IRI) contributes significantly to posttransplant graft dysfunction. An emphasis, therefore, has been directed toward the identification of novel renoprotective agents. In this study, the renoprotective effect of tetrodotoxin (TTX) alone, or in combination with a thromboxane synthetase inhibitor (OKY-046), was investigated in a 60-min warm ischemia, 72-h reperfusion, IRI rodent model. Unilateral nephrectomized rats were treated with the test vehicle alone, 1, 2, or 4 microgram/kg of TTX or 2 mg/kg of OKY-046 intravenously, either 15 min pre- or postischemia, or 2 microgram/kg TTX administered simultaneously with OKY-046 (2 mg/kg), following the ischemic interval. Baseline, 24, and 72 h mean plasma creatinine (Cr) and urea nitrogen (BUN) were compared. Maximal renoprotection was demonstrated by significantly improved 72-h Cr and BUN levels with the 2 microgram/kg of TTX or with 2 mg/kg of OKY-046, each administered after ischemia (ischemic control Cr = 8. 01 +/- 1.07 mg/dl vs TTX = 3.84 +/- 0.80 mg/dl, P = 0.008; vs OKY-046 = 4.0 +/- 1.5, P + 0.008; ischemic control BUN = 241.3 mg/dl +/- 32.8 vs TTX = 85.7 mg/dl +/- 18.7, P < 0.008; vs OKY-046 = 52.6 +/- 22.5, P = 0.008). The combination therapy utilizing TTX with OKY-046 resulted in reduced animal survival, demonstrating no renoprotection as measured with the biochemical parameters. These results support the renoprotective effects of TTX in a severe, rodent IRI model. The exact mechanism of action, as well as the therapeutic potential of TTX in preservation/transplantation, warrants further study.

Prenatal and postnatal management of hyperprostaglandin E syndrome after genetic diagnosis from amniocytes

OBJECTIVE

To describe prenatal genetic diagnosis in hyperprostaglandin E syndrome (HPS) and the effect of indomethacin therapy on the course of the disease before birth and in the neonatal period.

METHODS

Mutational analysis of the ROMK channel gene (KCNJ1) from amniocytes by single-strand conformational analysis and direct sequencing. Review of the clinical and laboratory findings during pregnancy and the neonatal period in two siblings affected with HPS.

RESULTS

Compound heterozygosity of the fetus in KCNJ1 (D74Y/P110L) confirmed the clinical diagnosis of HPS at 26 weeks of gestation. Indomethacin therapy from 26 to 31 weeks prevented further progression of polyhydramnios without major side effects. In contrast to the elder brother, who had been diagnosed at the age of 2 months, the neonatal course was uncomplicated. Hypovolemic renal failure after excessive renal loss of salt and water could be prevented and severe nephrocalcinosis did not occur.

CONCLUSIONS

Genetic diagnosis of HPS and subsequent prenatal indomethacin therapy seems to have a beneficial effect on the natural course of HPS, especially progression of polyhydramnios; therefore, extreme prematurity could be prevented. Also, postnatally the early diagnosis allows the effective water and electrolyte substitution before severe volume depletion.

Perioperative renal dysfunction and cardiovascular anesthesia: concerns and controversies

In patients with renal disease undergoing cardiovascular surgery, perioperative management continues to be a challenge. Traditional answers have turned into new questions with the introduction of new agents and the redesign of old techniques. For ARF prevention, early recognition of pending deleterious compensatory changes is critical. Theoretically, therapeutic intervention designed to prevent ischemic renal failure should be designed to preserve the balance between RBF and oxygen delivery on one hand and oxygen demand on the other. Maintenance of adequate cardiac output distribution to the kidney is determined by the relative ratio of renal artery vascular resistance to systemic vascular resistance. Indeed, it should not be surprising to learn that norepinephrine (despite its vasoconstricting effect) has been reported to have no deleterious renal effects in patients with low systemic vascular resistance. Until recently, strategies for the treatment of ARF have been directed to supportive care with dialysis (to allow tubular regeneration). Various therapeutic maneuvers have been introduced in an attempt to accelerate the recovery of glomerular filtration, including dialysis, nutritional regimens, and new pharmacologic agents. A recent small prospective trial of low-dose dopamine in the prophylaxis of ARF in patients undergoing abdominal aortic aneurysm repair showed no benefit in those patients receiving dopamine. Conversely, the effects of intravenous atrial natriuretic peptide in the treatment of patients with ARF appear to offer benefit in patients with oliguria. Among 121 patients with oliguric renal failure, 63% of those who received a 24-hour infusion of atrial natriuretic peptide required dialysis within 2 weeks compared with 87% who did not. Whether this effect will be borne out in the future remains to be determined. The administration of epidermal growth factor after induction of ischemic ARF in rats has been shown to enhance tubular regeneration and accelerate recovery of kidney function. Human growth factor administration has been shown to increase GFR 130% greater than baseline in patients with chronic renal failure, but no data for clinical ARF have been reported. In addition, there have been significant improvements in dialysis technology in the treatment of ARF. Modern dialysis uses bicarbonate as a buffer as opposed to acetate, which reduces cardiovascular instability, and has more precise regulation of volume removal. Dialysate profiles and temperatures improve hemodynamics and reduce intradialytic hypotension. Techniques of hemodialysis without anticoagulation have reduced bleeding complications. Finally, dialysis membranes activate neutrophils and complement less with the biocompatible membranes used today that reduce recovery time and dialysis treatment. Evidence indicates that activation of complement and neutrophils by older dialysis membranes caused a greater incidence of hypotension, adding to ischemic renal injury. It remains to be determined whether early and frequent dialysis with biocompatible membranes, as well as other therapeutic interventions, will increase the survival of patients with perioperative ARF.

Prostaglandin production contributes to exercise-induced vasodilation in heart failure

Endothelial release of prostaglandins may contribute to exercise-induced skeletal muscle arteriolar vasodilation in patients with heart failure. To test this hypothesis, we examined the effect of indomethacin on leg circulation and metabolism in eight chronic heart failure patients, aged 55 +/- 4 yr. Central hemodynamics and leg blood flow, determined by thermodilution, and leg metabolic parameters were measured during maximum treadmill exercise before and 2 h after oral administration of indomethacin (75 mg). Leg release of 6-ketoprostaglandin F1alpha was also measured. During control exercise, leg blood flow increased from 0.34 +/- 0.03 to 1. 99 +/- 0.19 l/min (P < 0.001), leg O2 consumption from 13.6 +/- 1.8 to 164.5 +/- 16.2 ml/min (P < 0.001), and leg prostanoid release from 54.1 +/- 8.5 to 267.4 +/- 35.8 pg/min (P < 0.001). Indomethacin suppressed release of prostaglandin F1alpha (P < 0.001) throughout exercise and decreased leg blood flow during exercise (P < 0.05). This was associated with a corresponding decrease in leg O2 consumption (P < 0.05) and a higher level of femoral venous lactate at peak exercise (P < 0.01). These data suggest that release of vasodilatory prostaglandins contributes to skeletal muscle arteriolar vasodilation in patients with heart failure.

Evaluation of chronic oral toxicity and carcinogenic potential of lornoxicam in rats

As part of the preclinical development program for lornoxicam, a novel non-steroidal anti-inflammatory drug (NSAID), its chronic oral toxicity and carcinogenic potential was assessed in Sprague-Dawley rats. Male and female rats were administered lornoxicam by oral gavage at 0, 0.06, 0.16 or 0.40 mg/kg/day for 12 months or at 0, 0.01 or 0.06 mg/kg/day in a supplementary low-dose study of the same duration (main group: 20/sex/group; 4-wk recovery: five/sex/group; satellites for electrocardiography and toxicokinetics: five/sex/group). Drug-related toxicity mainly comprised mortality, reduced body weight gain, clinico-pathological changes indicative of anaemia resulting from blood loss, and renal damage, renal papillary necrosis and gastrointestinal mucosal lesions. The kidney-associated changes were not completely reversible during the recovery period. Toxicokinetic investigations demonstrated a dose-linear absorption of the drug. In female rats the terminal half-life was about twice that in males which led to a higher exposure of this gender to lornoxicam. A dose of 0.01 mg/kg/day was established as no-observed-effect level. In a 104-wk carcinogenicity study, lornoxicam was administered by oral gavage to male and female rats (50/sex/group) at 0 (control 1), 0 (control 2), 0.0625, 0.125 or 0.250 mg/kg/day. In females only, the high dose was reduced twice during the study due to toxicity observed (0.250 to 0.200 to 0.160 mg/kg/day). Drug-related changes were similar to those in the chronic studies and consistent with the anticipated side-effects of NSAIDs. No carcinogenic potential was revealed.

Impaired response to furosemide in hyperprostaglandin E syndrome: evidence for a tubular defect in the loop of Henle

In hyperprostaglandin E syndrome (HPS) renal wasting of electrolytes and water is consistently associated with enhanced synthesis of prostaglandin E2. In contrast to Bartter or Gitelman syndrome (BS/GS), HPS is characterized by its severe prenatal manifestation, leading to fetal polyuria, development of polyhydramnios, and premature birth. This disorder mimics furosemide treatment with hypokalemic alkalosis, hypochloremia, isosthenuria, and impaired renal conservation of both calcium and magnesium. Therefore the thick ascending limb of the loop of Henle seems to be involved in HPS. To characterize the tubular defect we investigated the response to furosemide (2 mg/kg) in HPS (n = 8) and BS/GS (n = 3) 1 week after discontinuation of long-term indomethacin treatment. Sensitivity to furosemide was completely maintained in patients with BS/GS. The diuretic, saluretic, and hormonal responses were similar to those of a control group of healthy children (n = 13), indicating an intact function of the thick ascending limb of the loop of Henle in BS/GS. In contrast, patients with HPS had a marked resistance to this loop diuretic. Furosemide treatment increased urine output by 7.5 +/- 0.7 ml/kg per hour in healthy control subjects but only by 4.4 +/- 1.2 ml/kg per hour (p < 0.5) in children with HPS. In parallel, the latter also had a markedly impaired saluretic response (delta Cl(urine) 0.14 +/- 0.04 mmol/kg per hour vs 0.85 +/- 0.09 mmol/kg per hour, p < 0.001; delta Na(urine) 0.23 +/- 0.06 mmol/kg per hour vs 0.77 +/- 0.09 mmol/kg per hour, p < 0.001). Furosemide therapy further enhanced prostaglandin E2 excretion in patients with HPS (54 +/- 17 to 107 +/- 28 ng/hr per 1.73 m2, p < 0.05), whereas no significant effect was observed in healthy children (20 +/- 3 to 12 +/- 3 ng/hr per 1.73 m2). We conclude that a defect of electrolyte reabsorption in the thick ascending limb of the loop of Henle plays a major role in HPS.

Polyunsaturated fatty acid deficiency in liver diseases: pathophysiological and clinical significance

Polyunsaturated fatty acid (PUFA) deficiency occurs in advanced cirrhosis and other liver diseases (acute hepatitis, cholestasis). Long-chain PUFA deficit in cirrhosis is due to both essential fatty-acid (EFA) deficiency and impaired PUFA biosynthesis. Although hepatic insufficiency itself mostly accounts for this phenomenon, other factors such as associated malnutrition also play a role. PUFA deficiency in cirrhosis probably has a wide array of both cellular and clinical consequences, but, at present, they have been difficult to prove. In addition, the route, dosage, and safety of PUFA supplementation in these patients needs extensive investigation in the future.

Evaluation of the thromboxane A2 synthetase inhibitor OKY-046 in a warm ischemia-reperfusion rat model

The pathophysiology of ischemia-reperfusion renal injury is mediated, in part, by the generation of the vasoconstricting prostanoid thromboxane A2 (TXA2). This study was undertaken to evaluate the renoprotective effects, as well as the optimal timing and dosage, of a selective thromboxane synthetase inhibitor, OKY-046, in a unilateral nephrectomized, 60 min ischemia, 72 hr reperfusion, rodent model. Forty-one rats were subjected to right nephrectomy only (group A), or right nephrectomy with 60 min of left renal ischemia and treatment with inactive vehicle only (group B), or 2 mg/kg or 4 mg/kg of OKY-046 administered intravenously before (groups C and D) or after (groups E and F) pedicle clamping. Outcome variables included animal survival; change in kidney weight; 0, 24, and 72 hr plasma creatinine (CR); urea nitrogen (BUN); thromboxane B2 (TXB2) and 6-keto prostaglandin F(1alpha) (6 kPGF(2alpha)) levels; creatinine clearance (CRCL); and histologic evidence of renal injury. Animal survival and postperfusion kidney weight were not significantly different among the groups. However, renal functional parameters were significantly improved with the 2 mg/kg dose of OKY-046 administered after renal ischemia. (group B 72 hr Cr= 8.01 +/- 1.1 mg% vs. group E=3.99 +/- 1.5 mg%, and group B 72 hr BUN=241.3 +/- 32.8 mg% vs. group E=52.6 +/- 22.5 mg%). The CRCL was also improved in group E vs. group B, although these results did not reach statistical significance (group B=0.069 ml/min vs. group E=0.194 ml/ min). The 24 hr TXB2 levels were significantly increased in group B (0 hr=754.1 +/- 219.4 pg/ml vs. 24 hr=2055.9 +/- 550.0 pg/ml), and pre- or posttreatment with OKY-046 abrogated this increase (group C 0 hr=517.1 +/- 80.9 pg/ml vs. 24 hr=384.7 +/- 251.5 pg/ml, and group E 0 hr=781.6 +/- 390.4 pg/ml vs. 24 hr=183.0 +/- 81.4 pg/ml). The 24 hr 6 kPGF(1alpha) levels decreased in all groups, whereas 72 hr 6 kPGF(1alpha) levels increased above baseline in groups A, C, and E, but not in group B. These data demonstrate the beneficial effects of thromboxane A2 synthesis inhibition in the setting of ischemia-reperfusion injury and suggest that this renoprotection correlates with late vasodilatory prostanoid synthesis.

Role of platelets in progressive glomerular diseases

There is increasing evidence that platelets are involved in the pathogenesis of glomerulonephritis. Intraglomerular platelets or their degradation products are observed in biopsies from patients with lupus nephritis, mesangioproliferative, membranous or IgA nephropathy. Moreover shortened platelet survival in patients with various glomerular diseases has also been described. In models of experimental glomerulonephritis, platelets may participate in glomerular injury, together with other mediators, by complex mechanisms. As extensively documented, platelets release within the glomerulus vasoactive, chemotactic and mitogenic substance that interact with a number of soluble mediators generated by renal resident or inflammatory cells and contribute to amplify glomerular injury. Thus platelet-activating factor and other platelet secretory products, polycationic macromolecules, platelet factor 4 and beta-thromboglobulin, alter glomerular permeability to proteins and enhance immune-mediated glomerular injury. Platelet-derived factors, like platelet-derived growth factor (PDGF) and transforming growth factor beta (TGF beta) mediate renal disease progression in experimental and human glomerulonephritis via their chemotactic activity for infiltrating leucocytes and their effect of promoting extracellular matrix synthesis by resident renal cells. In these settings increased renal expression of PDGF and TGF beta has correlated with clinical features. Specific PDGF and TGF beta inhibitors ameliorated experimental glomerular disease. A wide variety of therapies to inhibit platelet function have been employed over the years, however the results of clinical studies are controversial and do not allow conclusions to be drawn about the efficacy of anti-platelet agents in progressive renal disease. Identification of specific platelet inhibitors or interventions specific for platelet secretory products and their target cells will be crucial for understanding the exact role of platelets and their products in glomerular disease.

Transmembrane signaling in kidney health and disease

Transmembrane signal transduction is the process whereby a ligand binds to the external surface of the cell membrane and elicits a physiological response specific for that ligand and cell type. It is now appreciated that numerous disease states represent disturbances in normal transmembrane signaling mechanisms. In the current paper, we focus our attention on the mesangial cell of the glomerular microcirculation as a prototypical model system for understanding normal and abnormal transmembrane signaling processes. Among the major receptor and effector mechanisms for transmembrane signal transduction in the mesangial cell, this paper emphasizes the phospholipase effector response to growth factors and vasoactive hormones. The post-translational and transcriptional pathways for regulation of phospholipase C and phospholipase A2 are described, including consideration of perturbations in these systems that characterize two disease models, namely: acute cyclosporine nephrotoxicity and early diabetic glomerulopathy.

Nephrotoxicity of xenobiotics

Nephrotoxicity can be grouped by the xenobiotics place of action, by the clinical presentation or by the generic toxic effect. The latter can be dose related, indirect, idiosyncratic or allergic. Nephrotoxicity of lithium, demeclocycline, aminoglycosides, cyclosporine, mercuric ion, nonsteroidal anti-inflammatory drugs, methoxyflurane, ethylene glycol, D-penicillamine and methicillin is reviewed in light of all these three viewpoints, but emphasis is on toxic mechanisms.

Peripheral haemodynamic effects of inhibition of prostaglandin synthesis in congestive heart failure and interactions with captopril

OBJECTIVES

To investigate the role of prostaglandins in maintaining circulatory homoeostasis in chronic heart failure and the hypothesis that an increase in vasodilatory prostaglandin synthesis may contribute to the actions of angiotensin converting enzyme inhibitors in heart failure.

DESIGN

Randomised, double blind, placebo controlled studies. Cardiac output and renal and limb blood flow were measured after oral indomethacin 50 mg or placebo followed by "open" intravenous infusion of prostaglandin E2 (study A). In a second study the same measurements were made after oral indomethacin 50 mg or placebo was given 30 min before "open" captopril (study B).

METHODS

Blood pressure was measured using a mercury sphygmomanometer. Cardiac output was determined by Doppler interrogation of blood flow in the ascending aorta and echocardiographic measurement of aortic root diameter. Renal blood flow was calculated from the effective renal plasma flow measured by p-aminohippurate clearance and the haematocrit, and glomerular filtration rate by endogenous creatinine clearance. Limb blood flow was measured by venous occlusion plethysmography using mercury in silastic strain gauges. The concentration of plasma prostaglandin E2 was measured by radioimmunoassay.

SETTING

University department of cardiovascular medicine.

PATIENTS

12 patients with chronic stable heart failure before starting treatment with angiotensin converting enzyme inhibitors.

RESULTS

Indomethacin resulted in adverse effects on cardiac output, systemic vascular resistance, renal blood flow, glomerular filtration, urinary sodium excretion, and calf vascular resistance. Changes were reversed with infusion of prostaglandin E2. Pretreatment with indomethacin resulted in the attenuation of the acute increase in cardiac output and decrease in systemic vascular resistance that occurred with captopril. Similarly, an increase in renal blood flow with captopril was attenuated by indomethacin.

CONCLUSIONS

The acute adverse effects of indomethacin on central and peripheral haemodynamic and renal function suggest that prostaglandins have a significant role in the regulation of peripheral blood flow and renal function in patients with stable chronic heart failure. The attenuation by indomethacin of captopril induced improvements in haemodynamic function and renal blood flow is consistent with the hypothesis that captopril may act in part via an increase in prostaglandin synthesis.

Effect of nephropathogenic infectious bronchitis viruses on renal function in young male broiler chickens

1. The acute effects of challenge with Australian T-strain infectious bronchitis virus (IBV) on renal function were evaluated, following primary vaccination in 1-d-old male broilers. 2. Challenge with T-strain IBV decreased body weight and induced kidney hypertrophy and kidney asymmetry. 3. Haematocrit was reduced in birds challenged with the Australian T-strain IBV and plasma uric acid was elevated in unvaccinated birds exposed to the IBV challenge. 4. Challenge with T-strain IBV caused significant increases in urinary water losses, accompanied by decreased urine osmolality and increased fractional excretion of sodium, calcium and potassium. 5. Vaccination at 1-d-old with Vic S-strain IBV provided a limited degree of protection against an heterologous challenge with T-strain IBV at 15 d of age.

Glomerular prostaglandins modulate vascular reactivity of the downstream efferent arterioles

The balance of vascular resistance in afferent (Af-) and efferent arterioles (Ef-Arts) is a crucial factor that determines glomerular hemodynamics. We have recently reported that when Ef-Arts were perfused from the distal end of the Af-Art through the glomerulus (orthograde perfusion; OP), both angiotensin II (Ang II) and norepinephrine (NE) induced much weaker constriction than they did when Ef-Arts were perfused from the distal end (retrograde perfusion; RP). This difference was not affected by inhibiting synthesis of nitric oxide. In the present study, we tested the hypothesis that glomerular prostaglandins (PGs) may modulate vascular reactivity of the downstream Ef-Art. In addition, we examined the possible modulatory role of PGs in the Af-Art responses to Ang II or NE. Both Ang II and NE caused dose-dependent constriction of Ef-Arts with either OP or RP; however, the constriction was stronger in RP. At 10(-8) M, Ang II decreased Ef-Art diameter by 35 +/- 3.5% in OP (N = 9) compared to 73 +/- 3.9% in RP (N = 5), while 10(-6) M NE decreased the diameter by 25 +/- 3.6% in OP (N = 9) compared to 62 +/- 7.2% in RP (N = 5). Pretreatment with 5 x 10(-5) M indomethacin (Indo) did not alter basal diameter with either method of perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of angiotensin II type 1 receptor antagonist on urinary prostaglandin E2 excretion following furosemide in rats

The present study was undertaken to examine an effect of an angiotensin II type 1 (AT1) receptor antagonist on urinary prostaglandin E2 (PGE2) excretion following furosemide, a loop diuretic, in rats. Furosemide (30 mg/kg) was given orally with or without pretreatment with derapril (30 mg/kg), an angiotensin converting enzyme inhibitor, TCV-116 (1 mg/kg), an AT1 receptor antagonist, or losartan (10 mg/kg), another AT1 receptor antagonist. The 6-hour urine was collected following furosemide, and the urinary excretion of PGE2 was determined. The urinary PGE2 increased significantly following furosemide alone. However, such a furosemide-induced increase was not observed with pretreatment with derapril, TCV-116 or losartan. These results suggest that the increased urinary excretion of PGE2 following furosemide is blunted by derapril, TCV-116 and losartan. As TCV-116 and losartan are selective AT1 receptor antagonists, the effect of furosemide on renal PGE2 production, as reflected by the urinary PGE2, might be mediated by an activation of AT1 receptors.

Effects of KW-3635, a specific thromboxane A2-receptor antagonist, on the development of lupus nephritis in NZB x NZW F1 mice

We examined the effect of KW-3635, a specific thromboxane A2 (TXA2)-receptor antagonist, on the development of lupus nephritis in NZB x NZW F1 mice. KW-3635 was orally given once a day for 33 weeks beginning at eight weeks of age. In the control group, the mice began to die at 39 weeks of age, showing severe proteinuria and histopathologic abnormality in the renal glomeruli. Administration of KW-3635 (30 mg/kg/day) significantly reduced urinary protein excretion (1.7 +/- 0.9 vs. 8.5 +/- 2.4 mg/6 hr/mouse, P < 0.01), mortality (1/18 vs. 6/19, P < 0.05) and the histopathologic score of the kidney examined at 41 weeks of age. Thus, chronic administration of KW-3635 markedly attenuated the renal disease in NZB x NZW F1 mice, suggesting that TXA2 is an important mediator of the pathogenesis in this murine model of lupus nephritis.

Evaluation of the renal protective effect of misoprostol in elderly, osteoarthritic patients at risk for nonsteroidal anti-inflammatory drug-induced renal dysfunction

An age greater than 60 and diuretic use have been implicated as risk factors for nonsteroidal anti-inflammatory drug (NSAID)-induced decreases in renal function. Misoprostol, a prostaglandin E1 analog, was studied in nine elderly osteoarthritic patients at risk for NSAID-induced renal dysfunction to determine whether it could prevent NSAID-induced renal dysfunction. Subjects received ibuprofen 2400 mg/day and either misoprostol 800 mcg/day or placebo for 14 days in a randomized, double-blinded, crossover trial. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) studies using inulin and PAH plasma clearance, urinary prostaglandin E2 (PGE2) and protein excretion, and serum electrolytes were obtained at baseline, after the first dose, and on day 7 and 14 of each treatment period. Prostaglandin E2 excretion was significantly reduced after the first dose of ibuprofen and throughout the 14 days in both the misoprostol and placebo treatment groups. No statistically significant differences in GFR, ERPF, protein excretion, serum potassium, or serum sodium were detected between misoprostol and placebo treatment during the 14 days of ibuprofen treatment. However, a subset of two patients who exhibited a decrease of greater than 20% in GFR during placebo treatment, appeared to demonstrate an attenuation of this decline when treated with misoprostol. Effect of time, independent of treatment group, indicated that ERPF was significantly decreased from baseline after the first dose of ibuprofen (P < or = 0.05), whereas GFR was notably diminished from baseline on day 14 only (P < or = 0.05). Misoprostol does not influence GFR and ERPF in unselected subjects purportedly at risk for NSAID-induced renal dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Potentiation of the antireactive, antiasthmatic effect of inhaled furosemide by inhaled lysine acetylsalicylate

Nonsteroid antiinflammatory drugs interfere with the diuretic activity of furosemide, implying that this effect is at least partially dependent on renal prostaglandin synthesis. To investigate whether prostaglandin production could also modulate the bronchial antireactive activity of this diuretic drug, we investigated the effect of inhaled lysine acetylsalicylate (162 mg) and of furosemide (18 mg), alone and in combination, on the bronchial obstructive response to ultrasonically nebulized water in asthmatic patients. The study was also prompted by the conflicting results obtained in previous studies of oral nonsteroid antiinflammatory drugs. Fifteen asthmatic patients underwent bronchial challenge with a mist of ultrasonically nebulized distilled water at the same time of day on four occasions, 2-4 days apart, 15 min after premedication according to a double-blind, randomized protocol. After placebo, mean PD15 to water mist did not differ from a preliminary test (2.1 +/- 0.2 and 2.5 +/- 0.4 ml, M +/- SE, respectively). After lysine acetylsalicylate, mean PD15 rose to 5.0 +/- 0.7 ml (2.8 +/- 0.6 times higher than placebo); after furosemide, to 9.0 +/- 1.5 ml (4.4 +/- 0.9 times over placebo); and after the two drugs in combination, to 32.2 +/- 5.6 ml (16.3 +/- 3.0 times higher than placebo). Similar results were obtained with inhaled indomethacin, whereas sodium salicylate had no effect. These data indicate that the bronchial antireactive activity of inhaled furosemide is greatly enhanced by inhaled lysine acetylsalicylate through a mechanism which probably involves inhibition of the local synthesis of prostaglandins, and could have therapeutic implications.

Tiaprofenic acid inhibits the renal reabsorption of sulfate in rats

The objectives of the current investigation were: (1) to examine the effects of the nonsteroidal anti-inflammatory drug, tiaprofenic acid (TA), on sulfate renal reabsorption, and (2) to determine if concomitant prostaglandin E2 (PGE2) could reverse these effects. In crossover studies, female Lewis rats (n = 9) received either TA (as an intravenous (i.v.) bolus injection of 15 mg/kg and constant infusion of 0.02 mg/min) or its vehicle for 6 h. A blood sample was obtained at 5 h and urine was collected between 4 and 6 h. At a steady-state TA serum concentration of approximately 190 micrograms/ml, the PGE2 urinary excretion rate was inhibited by > 90% with no change in glomerular filtration rate (GFR), as measured by creatinine clearance. TA administration resulted in a significant decrease in serum sulfate concentrations (0.65 +/- 0.22 vs 1.1 +/- 0.15 mM, mean +/- SD, p < 0.01) and increase in sulfate clearance ratio (0.32 +/- 0.14 vs 0.13 +/- 0.06, p < 0.01) when compared to the vehicle-treated period. There was also a significant decrease in the fraction of sulfate reabsorbed by the kidneys (0.68 +/- 0.14 vs 0.87 +/- 0.06 in the vehicle-treated period, p < 0.01). In a second crossover study, rats received either TA or TA plus PGE2. PGE2 was administered as an infusion (0.1 micrograms/min) beginning 210 min after the start of the TA infusion. An additional group of rats served as controls and received both vehicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal and general tolerability of repeated doses of nimesulide in normal subjects

The renal and general tolerability of nimesulide was studied in 16 healthy men, randomised to 4 groups of 4 subjects. The groups all underwent 2 treatment periods of 7 days each, separated by a washout period of 14 days. The second treatment period was always at a higher dosage level than the first. There were 4 dosage regimens: placebo, and nimesulide 200, 300 and 400mg, all given twice daily by mouth according to a double-blind design. The tolerability of nimesulide was assessed by regular clinical examination, nondirected questions about adverse events, haematological and biochemical screening, and daily urine testing. Plasma and urinary concentrations of Tamm-Horsfall glycoprotein (THG), urinary retinol-binding protein (RBP) and beta-N-acetyl glucosaminidase (NAG) on days 1, 3, 7, and 10 of each period were used as selective indicators of nephrotoxicity. The highest dose of nimesulide (800mg daily) was associated with abdominal pain and indigestion in 5 of 8 recipients. The 400 and 600mg daily dosages were well tolerated. There were no clinically significant alterations in the haematological or biochemical screening tests during the study, and daily urinalysis remained normal throughout. The renal toxicity tests showed no evidence of nephrotoxicity associated with the administration of nimesulide in 14 subjects. The other 2 subjects each had modest increases in either urinary THG or NAG concentrations during treatment with nimesulide 800mg daily, but the results of their other tests remained normal. The study, therefore, showed only equivocal evidence of minor renal toxicity with nimesulide 800mg daily. Nimesulide 400 and 600mg daily were well tolerated in all respects, even though these dosages are higher than those recommended for clinical use.

Effect of sodium loading (3% NaCl) on arachidonic acid biosynthesis in rat liver microsomes

Sodium loading increases arachidonic acid (AA) metabolism by way of the prostaglandins(PGs) from series 2. Its effect on AA biosynthesis remains unknown. The purpose of the present study was to investigate the influence of sodium loading on the fatty acid composition of liver and liver microsomes, and the liver microsomal delta-6 and delta-5 desaturations of linoleic acid (LA) into AA. We found a decrease of LA and dihomo-gamma-linolenic acid (DGLA) levels in liver total lipids of Wistar rats receiving hypernatriuretic drinking water (NaCl 3%) for 60 days. At the same time AA increased. DGLA decreased and AA increased in liver microsomal total lipids. 1(14) C-LA delta-6 desaturase and 2(14) C-DGLA delta-5 desaturase activities increased in liver microsomes. These results show that, in addition to its influence on the regulation of glomerular filtration, sodium loading is involved in the regulation of liver AA biosynthesis.

A trial of the prostaglandin E1 analogue, enisoprost, to reverse chronic cyclosporine-associated renal dysfunction

Cyclosporine (CYA) reduces the renal synthesis of prostaglandins of the E series (PGE). Analogue of PGE1 have been shown to mitigate the vasoconstriction and abnormal renal function of experimental acute CYA nephrotoxicity. We examined the hypothesis that the orally bioavailable PGE analogue enisoprost (EP) would improve renal function in renal transplant recipients chronically exposed to CYA. In a randomized double-blind study, 40 patients at two centers who were being monitored for 3 to 30 months after renal transplantation, were allocated to receive either EP 100 micrograms orally four times daily or placebo (P) for 2 weeks. CYA dosing was fixed at existing levels. There could be no evidence of concurrent acute renal injury, including that of acute rejection. Glomerular filtration rate (GFR) was measured by the clearance of radiolabeled DTPA, while effective renal plasma flow (ERPF) was measured as the clearance of p-aminohippuric acid (PAH). The acute effects of EP were examined twice, by comparing immediate postdose to predose values for GFR and ERPF on day 1 and again on day 14. Chronic effects were examined by comparing baseline (predose) values only for GFR and ERPF between days 1 and 14 and by an examination of creatinine clearances (CCR) on days 0, 14, and 21. At enrollment, patients were well matched for renal function (CCR:EP 47 +/- 5 v P 49 +/- 4 mL/min/1.73 m2; P = NS). Baseline demographics were similar, although patients treated with EP were older (46 +/- 2 v 36 +/- 3 years, mean +/- SEM, P = 0.003). CYA doses and blood levels did not change significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of prostaglandin effect on sodium balance and hyperreninemia in adrenalectomized rats

Glucocorticoids are known inhibitors of prostaglandin production. Prostaglandin E2 (PGE2) and prostacyclin (PGI2) are promoters of natriuresis and renin release. Excessive prostaglandin production, therefore, might contribute to the altered sodium balance and renin release observed in primary adrenal insufficiency. To test this hypothesis, sodium balance and prostaglandin production were measured in adrenalectomized rats and in animals receiving prostaglandin inhibitors or replacement dexamethasone. Compared to sham-operated controls, adrenalectomized rats had decreased two-day sodium balance and elevated plasma renin concentration (PRC), renal PGE2 production, and renal 6-ketoprostaglandin F1 alpha (6kPGF1 alpha, the nonenzymatic metabolite of PGI2); however, no appreciable change in aortic 6kPGF1 alpha production was observed. Dexamethasone given to adrenalectomized rats normalized PRC but had no effect on sodium balance or prostaglandin production. Likewise, prostaglandin inhibitors did not alter the sodium balance or decrease the PRC post adrenalectomy. These data confirm renal prostaglandin production is increased in adrenalectomized rats, but suggest that the elevation is not due directly to glucocorticoid deficiency. Further, PRC levels in adrenal insufficiency do not appear to be prostaglandin mediated. In conclusion, excessive renal prostaglandin production does not contribute to altered sodium balance or increased PRC in adrenalectomized rats.

The protective effect of FK506 pretreatment against renal ischemia/reperfusion injury in rats

The effect of pretreatment with FK506 on renal ischemia and reperfusion (I/R) injury was investigated using a rat model. Animals were assigned to one of two groups (20 rats each). Group 1 animals (controls) received 0.5 ml saline while group 2 animals received FK506 (0.3 mg/kg), administered intravenously 24 hr prior to the induction of renal ischemia. A 60-min period of ischemia of the right kidney was induced, and upon reperfusion a left nephrectomy was performed. Blood samples for estimation of BUN, creatinine, and tumor necrosis factor were collected on days 0 (preischemia), 1, 2, 3, 5, 7, and 10 (postischemia). Rats were sacrificed after day 10 and renal tissue was examined histologically. All animals survived the ischemic episode. FK506 pretreatment significantly reduced the serum levels of BUN (P less than 0.02), creatinine (P less than 0.02), and TNF (P less than 0.05) as compared with that seen in controls. Histologically, at day 10, the kidneys showed the expected sequelae of prior renal I/R with various degrees of tubular damage. However, no objective differences were evident between the two groups. Based upon these data, it can be concluded that (1) FK506 pretreatment ameliorates the functional renal injury associated with I/R, (2) renal ischemia induces the release of TNF, and (3) FK506 pretreatment results in a significant inhibition of TNF production. These data suggest that the release of TNF may be responsible for the increasing of BUN and creatinine levels seen after renal I/R and that pretreatment of renal donors with FK506 may improve renal function in the immediate post-transplant period.

Effects of indomethacin, aspirin, and acetaminophen on ethanol diuresis in rats

A number of studies have indicated that prostaglandin synthetase inhibitors (PGSI) can antagonize several effects of ethanol. This study examines the influence of intraperitoneal pretreatment with the PGSI indomethacin (5.0 or 10.0 mg/kg), aspirin (15.0 or 30.0 mg/kg) and acetaminophen (15.0 or 30.0 mg/kg) on the diuretic effect produced by orally administered ethanol (4.0 g/kg) in female rats. Pretreatments with indomethacin and aspirin led to an antagonism of ethanol's diuretic effect. Nevertheless, acetaminophen failed to antagonize this effect. These results are in agreement with data from the literature on PGSI versus ethanol and suggest possible involvement of prostaglandins in the diuretic effect of ethanol.

FK 506 reduces the injury experienced following renal ischemia and reperfusion

The effect of FK 506 pretreatment on renal ischemia and reperfusion (I/R) injury was investigated. Adult male rats were assigned to one of two groups (20 animals each). Group 1 (controls) received 0.5 mL saline while group 2 received FK 506 (0.3 mg/kg) intravenously 24 h prior to the induction of renal ischemia. After a 60-min period of ischemia of the right kidney, a left nephrectomy was performed. Blood for BUN, creatinine, and tumor necrosis factor (TNF) was obtained prior to ischemia and on days 1, 2, 3, 5, 7, and 10. All surviving animals were sacrificed at day 10. FK 506 pretreatment reduced the serum levels of BUN (p less than .02), creatinine (p less than .02) and TNF (p less than .05) as compared to that seen in controls. Based upon these data, it appears that: (a) renal ischemia induces the release of TNF; (b) FK 506 pretreatment inhibits TNF production; and (c) FK 506 reduces renal injury association with I/R.

Prostaglandins in the kidney, urinary bladder and gills of the rainbow trout and European eel adapted to fresh water and seawater

Prostaglandins in kidney, gills, and urinary bladder of freshwater-adapted and seawater-adapted rainbow trout, Oncorhynchus mykiss (= Salmo gairdneri), and European eel, Anguilla anguilla, were determined by solid-phase extraction of tissue homogenates and high-pressure liquid chromatography. Prostaglandins E2, E1, F1 alpha, F2 alpha, and D2 and the more stable metabolite of prostacyclin, 6-keto F1 alpha, occurred in these osmoregulatory tissues. In gill filaments and kidneys of both eel and trout, prostaglandins D2 and 6-keto F1 alpha were major prostaglandins. Concentrations of these prostaglandins were significantly lower in the eel after seawater adaptation, but not in the trout. The urinary bladder of the trout contained the highest levels of prostaglandins; bladders of seawater-adapted trout contained prostaglandin D2 at 6.7 ng/mg wet tissue, the highest level of any prostaglandin determined in the present studies. Prostaglandin D2 was not detected in bladders of freshwater-adapted trout.

Minimization of indomethacin-induced reduction in renal function by misoprostol

A prospective, randomized, open-label, triple crossover comparison of the effects of indomethacin, misoprostol, or the combination, on renal function was performed to assess the ability of an oral prostaglandin E analogue, misoprostol, to minimize indomethacin-induced decline in renal function in middle-aged women. Twelve healthy women (mean age: 60.5 +/- 1.6 yr) with normal renal function (serum creatinine: 81 +/- 9 umol/L) were studied; six women were normotensive, and six women were hypertensive with their blood pressure controlled with 50-mg hydrochlorothiazide daily. All patients were placed on a 2-g sodium daily diet for 2 weeks before initiation of the study. The subjects were prospectively randomized to receive each of three 4-day treatments of indomethacin (25 mg q 6hr), misoprostol (200 mcg q 6hr), or the combination of drugs with a 4-day washout between each treatment period. Measurements of GFR (urine accumulation of 99mTc-DTPA) and RPF (serum disappearance 131I-Hippuran), and urine collections for electrolytes were obtained before the first treatment period and on the fourth day of each treatment period. Three of the six hypertensive patients and three of the six normotensive patients had a decrease (greater than 10%) in GFR associated with indomethacin therapy. When misoprostol was given with the indomethacin, four of these six patients did not experience a decline in GFR (baseline GFR for six patients: 75.4 +/- 6.6 mL/min/1.73m2, GFR after indomethacin: 57.8 +/- 9.5 mL/min/1.73m2, GFR with combination of indomethacin and misoprostol: 69.7 +/- 3.5 mL/min/1.73m2. RPF was not consistently altered by subacute/chronic dosing of indomethacin, misoprostol, or the combination of the drugs. The authors conclude that misoprostol ameliorates indomethacin-induced renal dysfunction in salt-restricted and diuretic-treated middle-aged women with normal serum creatinine.

The effect of the inhibition of prostaglandin synthesis on renal blood flow in fetal sheep

Treatment with prostaglandin synthesis inhibitors has been associated with oligohydramnios in the fetus. The presumed mechanism is a reduction in fetal renal blood flow. We examined the effect of meclofenamate administration on renal blood flow in chronically catheterized fetal sheep during normoxia and during moderate and severe hypoxia. Ten fetal sheep were made hypoxic twice at least 4 days after surgery: once in the presence and once in the absence of meclofenamate infusion. Renal blood flow and combined ventricular output were measured with radioactive microspheres. Prostaglandin synthesis blockade with meclofenamate caused no significant change in blood pressure, combined ventricular output, renal blood flow, or renal vascular resistance in either the normoxic or hypoxic animals. These data challenge the contention that prostaglandin activity protects the renal vascular bed of the fetus from vasoconstriction during hypoxia and they also do not support the hypothesis that prostaglandin synthesis inhibition causes oligohydramnios through reduction of fetal renal blood flow.