Purine Metabolite Concentrations Research Articles

Change in Lactate, Ammonia, and Hypoxanthine Concentrations in a 1-Year Training Cycle in Highly Trained Athletes: Applying Biomarkers as Tools to Assess Training Status.

Włodarczyk, M, Kusy, K, Słomińska, E, Krasiński, Z, and Zieliński, J. Change in lactate, ammonia, and hypoxanthine concentrations in a 1-year training cycle in highly trained athletes: applying biomarkers as tools to assess training status. J Strength Cond Res 34(2): 355-364, 2020-The aim was to determine changes in biomarker (LA, NH3, purine metabolites) blood concentration during graded exercise and recovery throughout an annual training cycle in highly trained athletes of different training profiles. The study included 12 sprinters (SP, 21-30 years), 11 triathletes (TR, 20-31 years), 12 futsal players (FU, 19-31 years), and 13 amateur runners (AM, 20-33 years). Purine metabolite (hypoxanthine, xanthine, uric acid), ammonia (NH3), and lactate (LA) concentrations were determined at rest, during an incremental treadmill exercise test (every 3 minutes), and during recovery (5, 10, 15, 20, and 30 minutes postexercise) in 4 phases of an annual training cycle. Purine metabolite concentration was determined from plasma, whereas LA and NH3 from whole blood. For LA during exercise and recovery, certain significant differences between training phases within groups were observed for FU, TR, and SP but not for AM. For NH3, the greatest differences between examination points were observed for SP and TR near maximal exercise and in the first few stages of recovery. For hypoxanthine (Hx), the largest amount of differences between examination points was observed for FU, TR, and FU throughout the entire exercise spectrum. Biomarker concentration dynamics change during an incremental exercise test and postexercise in an annual training cycle. Biomarker responses differ depending on training type and magnitude of training loads used in various phases of an annual training cycle. When assessing training status using an incremental exercise test throughout an annual training cycle, NH3 and Hx concentration changes are more sensitive compared with LA.

Molecular origin of surface-enhanced Raman spectra of E. coli suspensions excited at 532 and 785 nm using silver nanoparticle sols as sers substrates

Research into the molecular origin of surface-enhanced Raman spectra (SERS) of bacteria is a crucial step in assessing the future of SERS-based discrimination and identification of bacteria in clinical analysis, food quality control, etc. Previous studies have revealed that at 785 nm excitation wavelength SERS of bacterial cells placed on a solid surface functionalized with in-situ grown aggregated gold nanoparticles covered with SiO2 originate from a mixture of 6 purine derivatives (adenine, guanine, AMP, hypoxanthine, xanthine, and uric acid) that are released by the cells into the medium. The aim of the present work was to investigate whether such interpretation is possible with a different class of SERS substrates: silver nanoparticle sols at excitation wavelengths of 785 and 532 nm. The suspension of the Escherichia coli DH5α strain was used as a model bacterium. Sols of silver nanoparticles were obtained by reducing silver nitrate in the presence of alkaline hydroxylamine hydrochloride. Number-weighted mean hydrodynamic diameter of the particles was 43±2 nm. We confirm that at both excitation wavelengths the spectra can be best described as a superposition of 4 purine derivatives: adenine, guanine, hypoxanthine, and xanthine. Importantly, we have discovered that 1) the spectra of the purine mixture are characteristic of viable cells only; 2) due to the variations in the concentrations of purine metabolites released by the cells into the surrounding medium the spectra of a bacterial strain can vary significantly when a silver nanoparticle sol is used as a SERS substrate.

Concentrations of Purine Metabolites Are Elevated in Fluids from Adults and Infants and in Livers from Mice Fed Diets Depleted of Bovine Milk Exosomes and their RNA Cargos

Humans and mice absorb bovine milk exosomes and their RNA cargos. The objectives of this study were to determine whether milk exosome- and RNA-depleted (ERD) and exosome- and RNA-sufficient (ERS) diets alter the concentrations of purine metabolites in mouse livers, and to determine whether diets depleted of bovine milk alter the plasma concentration and urine excretion of purine metabolites in adults and infants, respectively. C57BL/6 mice were fed ERD (providing 2% of the microRNA cargos compared with ERS) and ERS diets starting at age 3 wk; livers were collected at age 7 wk. Plasma and 24-h urine samples were collected from healthy adults who consumed (DCs) or avoided (DAs) dairy products. Spot urine samples were collected from healthy infants fed human milk (HM), milk formula (MF), or soy formula (SF) at age 3 mo. Purine metabolites were analyzed in liver, plasma, and urine; mRNAs and microRNAs were analyzed in the livers of female mice. We found that 9 hepatic purine metabolites in ERD-fed mice were 1.76±0.43 times the concentrations in ERS-fed mice (P<0.05). Plasma concentrations and urine excretion of purine metabolites in DAs was ≤1.62±0.45 times the concentrations in DCs (P<0.05). The excretion of 13 purine metabolites in urine from SF infants was ≤175±39 times the excretion in HM and MF infants (P<0.05). mRNA expression of 5'-nucleotidase, cytosolic IIIB, and adenosine deaminase in mice fed ERD was 0.64±0.52 and 0.60±0.28 times the expression in mice fed ERS, respectively. Diets depleted of bovine-milk exosomes and RNA cargos caused increases in hepatic purine metabolites in mice, and in plasma and urine from human adults and infants, compared with exosome-sufficient controls. These findings are important, because purines play a role in intermediary metabolism and cell signaling.

Differences in Purine Metabolite Concentrations in the Diet of Managed and Free-Ranging Common Bottlenose Dolphins (Tursiops truncatus)

Differences in Purine Metabolite Concentrations in the Diet of Managed and Free-Ranging Common Bottlenose Dolphins (Tursiops truncatus)

Purine metabolism in response to hypoxic conditions associated with breath-hold diving and exercise in erythrocytes and plasma from bottlenose dolphins (Tursiops truncatus)

In mammalian tissues under hypoxic conditions, ATP degradation results in accumulation of purine metabolites. During exercise, muscle energetic demand increases and oxygen consumption can exceed its supply. During breath-hold diving, oxygen supply is reduced and, although oxygen utilization is regulated by bradycardia (low heart rate) and peripheral vasoconstriction, tissues with low blood flow (ischemia) may become hypoxic. The goal of this study was to evaluate potential differences in the circulating levels of purine metabolism components between diving and exercise in bottlenose dolphins (Tursiops truncatus). Blood samples were taken from captive dolphins following a swimming routine (n=8) and after a 2min dive (n=8). Activity of enzymes involved in purine metabolism (hypoxanthine guanine phosphoribosyl transferase (HGPRT), inosine monophosphate deshydrogenase (IMPDH), xanthine oxidase (XO), purine nucleoside phosphorylase (PNP)), and purine metabolite (hypoxanthine (HX), xanthine (X), uric acid (UA), inosine monophosphate (IMP), inosine, nicotinamide adenine dinucleotide (NAD+), adenosine, adenosine monophosphate (AMP), adenosine diphosphate (ADP), ATP, guanosine diphosphate (GDP), guanosine triphosphate (GTP)) concentrations were quantified in erythrocyte and plasma samples. Enzymatic activity and purine metabolite concentrations involved in purine synthesis and degradation, were not significantly different between diving and exercise. Plasma adenosine concentration was higher after diving than exercise (p=0.03); this may be related to dive-induced ischemia. In erythrocytes, HGPRT activity was higher after diving than exercise (p=0.007), suggesting an increased capacity for purine recycling and ATP synthesis from IMP in ischemic tissues of bottlenose dolphins during diving. Purine recycling and physiological adaptations may maintain the ATP concentrations in bottlenose dolphins after diving and exercise.

The combination of adenosine deaminase inhibition and deoxyadenosine induces apoptosis in a human astrocytoma cell line

Alterations in the functions of astrocytes contribute to the appearance of a variety of neurological pathologies. Gliomas, especially those of astrocytic origin, are particularly resistant to chemotherapy and are often characterized by a poor prognosis. Neuroblastoma is the tumour with the higher incidence in infants. Anticancer drugs can induce apoptosis and their cytotoxic effect is often mediated by this process. We have previously demonstrated that the combination of deoxycoformycin, a strong adenosine deaminase inhibitor, and deoxyadenosine is toxic for a human astrocytoma cell line. In fact, after 15 h of treatment, this combination increases both mitochondrial reactive oxygen species and mitochondrial mass, induces apoptosis as indicated by cytochrome c release from mitochondria and activation of caspase-3. These events are preceded by reduction in lactate release in the medium. In this work we demonstrate that after 8 h of incubation with deoxyadenosine and deoxycoformycin, caspase-8 is activated, mitochondrial mass increases and mitochondrial reactive oxygen species decrease. The addition of baicalein to the incubation medium reduces cell death and caspase-3 activity induced by deoxycoformycin and deoxyadenosine in combination. This protective effect is correlated to an increase of lactate released in the medium, a decrease in the intracellular levels of dATP, and an increase in ATP levels, as compared with the cells subjected to the treatment with deoxycoformycin and deoxyadenosine without any further addition. The effect of baicalein appears to be related to an inhibition of deoxyadenosine phosphorylation, rather than or in addition to the well known antioxidant activity of the compound. This work indicates that an astrocytoma cell line, reported to be resistant to mitochondria-dependent pathways of apoptosis, is indeed very sensitive to a manipulation affecting the balance of cellular purine metabolite concentrations. The same treatment is also cytotoxic on a neuroblastoma cell line, thus suggesting long term implications for cancer therapy

The effect of disease on the urinary purine metabolite concentrations in dogs

This prospective study was designed to determine the urinary concentrations of purine metabolites in healthy and diseased dogs. The goals were to test the hypothesis that urine concentrations of terminal...

Urine concentrations of xanthine, hypoxanthine and uric acid inUKCavalier King Charles spaniels

Xanthine urolithiasis and asymptomatic xanthinuria have been diagnosed in Cavalier King Charles spaniel dogs suggesting that primary xanthinuria may be a breed-related disorder, although its prevalence remains unclear. The hypothesis of this study was that asymptomatic xanthinuria is common in Cavalier King Charles spaniel dogs. Free catch urine samples were collected from 35 client-owned Cavalier King Charles spaniel dogs and from 24 dogs of other breeds. The purine metabolites were measured by high-performance liquid chromatography. The urine ratios of xanthine/creatinine and hypoxanthine/creatinine were calculated and compared between the two groups of dogs. The urine concentrations of purine metabolites were not significantly different between the two groups and were very low in both. The urine concentrations of xanthine in all 35 Cavalier King Charles spaniel were markedly lower than in the previously reported case of xanthine urolithiasis in a UK Cavalier King Charles spaniel dog. Asymptomatic xanthinuria was not detected in this UK Cavalier King Charles spaniel population. This data may be used as a reference for urinary purine metabolite concentrations in the dog.

Purine metabolites in fibromyalgia syndrome

ObjectiveTo evaluate serum purine metabolite concentrations in patients affected by fibromyalgia syndrome (FMS) and the relationships between their levels and FM clinical parameters. Design and methodsSerum purine levels were quantified using LC/UV–vis in 22 fibromyalgic females (according to the American College of Rheumatology classification criteria) and 22 healthy females. ResultsSignificantly higher serum inosine, hypoxanthine and xanthine levels (p<0.001) and significantly lower serum adenosine (p<0.05) were detected in the FMS patients vs healthy controls. Our data show a negative correlation between adenosine and Fibromyalgia Impact Questionnaire (FIQ). ConclusionsStudy results suggest that purines, in particular adenosine and inosine, may be involved in pain transmission in fibromyalgia.

Purine and Cytokine Concentrations in the Renal Vein of the Allograft During Reperfusion

The impairment of organ function derived from ischemia-reperfusion injury is still an important problem in solid organ transplantation. Cell alterations induced by ischemia prime the tissue for subsequent damage during the reperfusion phase. The aim of present study was to examine the association between changes in cytokine and purine metabolite concentrations in graft renal vein during reperfusion. The study included 17 recipients of cadaveric renal grafts: 10 men and seven women of overall mean age of 49 ± 7 years and cold ischemia time 25 ± 3 hour. The levels of interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-10, interferon (INF)-γ, tumor necrosis factor (TNF)-β, and TNF-α in renal graft vein plasma during 5 first minutes of reperfusion were quantified by flow cytometry. Increased concentrations of IL-6, TNF-α, and IL-1β were observed during reperfusion. The IFN-γ concentrations correlated negatively with xanthine (Xan) concentrations in renal vein blood during reperfusion, whereas there was a positive correlation between IL-2 and Xan concentrations. Moreover, the concentrations of IL-6 and IL-10 correlated negatively with hypoxanthine concentrations, and the concentrations of IL-4 also correlated negatively with Xan concentrations. The results of this study indicated the enhanced release of some cytokines during kidney graft reperfusion. It occurred in association with release of purine metabolites—the markers of energy status of renal tissue. Therefore, the enhanced cytokine production during reperfusion might influence ischemia-reperfusion injury and the early graft function.

Nitrogen Oxide Blockade Does Not Aggravate the Endothelin-1-induced Myocardial Ischemia and Release of Purine Metabolites from the Dog Heart

Increased intrapericardial levels of endothelin-1 (ET-1) induce myocardial ischemia and concomitant release of the purine metabolites adenosine (ADO), inosine (INO) and hypoxanthine (HXA) into the pericardial fluid. However, the potential modulatory role of nitrogen monoxide in compensating the ET-1-induced ischemic stress is not fully elucidated. The pericardial elevations of purine metabolite concentrations in the pericardial fluid after ET-1 administration (150 pmol/kg intrapericardially) were measured in the in situ dog heart with (n = 6) or without (n = 5) systemic nitrogen monoxide synthase blockade (30 mg/kg (G)-nitro-L-arginine methyl ester, followed by 6 mg/min intravenously). After control sampling, three consecutive pericardial infusate samples (ET1, ET2, ET3) were obtained for purine metabolite determinations (high-performance liquid chromatography-ultraviolet). It was found that intrapericardial ET-1 elevated the pericardial purine metabolite concentrations significantly in both groups. No significant differences were detected between the control and (G)-nitro-L-arginine methyl ester-treated groups in ischemic changes of pericardial ADOmax (+3.27 +/- 1.13 microM versus +1.84 +/- 0.56 microM), INOmax (+15.21 +/- 2.3 microM versus +12.09 +/- 4.04 microM) and HXAmax (+16.34 +/- 2.98 microM versus +17.09 +/- 5.22 microM) levels and in the maximal ST elevations (0.43 +/- 0.05 mV versus 0.61 +/- 0.08 mV). The hemodynamic variables did not change with ET-1 administration. In conclusion, systemic nitrogen monoxide synthase blockade does not aggravate the ET-1-induced acute myocardial ischemia and the release of purine metabolites, suggesting that endogenous nitrogen monoxide is not a supplementary factor to purine metabolites in this type of coronary adaptive responses.

CD26 expression correlates with a reduced sensitivity to 2'-deoxycoformycin-induced growth inhibition and apoptosis in T-cell leukemia/lymphomas.

dCF (2'-deoxycoformycin) is a potent inhibitor of ADA (adenosine deaminase), an enzyme regulating intra- and extracellular concentrations of purine metabolites. ADA exists as cytosolic and extracellular forms, the latter colocalized on the cell surface with CD26. Once the surface expression of CD26 and ADA in a panel of cell lines and primary samples of T-cell leukemia/lymphoma was defined, we correlated this expression with the antiproliferative and apoptotic effect of dCF. Surface expression of CD26 inversely correlated with the capability of dCF to inhibit cell growth and induce apoptosis both in T-cell lines and primary samples of T-cell malignancies. This conclusion was sustained by a decreased sensitivity to dCF-mediated proapoptotic and/or antiproliferative in vitro effects of: (a) leukemia/lymphoma T-cell lines expressing surface CD26/ADA complex; (b) primary CD26(+) T cell malignancies; and (c) normal T cells (CD26(+)) as compared with tumor T cells (CD26(-)) in unpurified samples from three cases of T-cell receptor gammadelta(+) T-cell malignancies characterized by a mixture of normal and neoplastic cells. This latter point was confirmed in vivo, in a patient affected by CD26(-) T-cell receptor gammadelta(+) hepatosplenic gammadelta(+) T-cell lymphomas treated on a compassionate basis with dCF. The inverse correlation between CD26 expression and sensitivity to dCF was also demonstrated in a lymphoblastic lymphoma case in which CD26 was expressed on circulating blasts at relapse but not at diagnosis, as well as in two H9 T-cell clones expressing or not expressing CD26 mRNA and protein. This study corroborates the notion of CD26 as a marker of poor prognosis for T-cell malignancies and delineates a role for CD26 as a predictor of poor response to dCF.

Endothelin-1-induced elevations in purine metabolite concentrations -- autoregulatory protection in the canine pericardium?

Pericardial fluid accumulates the cardioprotective purine metabolites, as well as the endogenous vasoconstrictor agent endothelin-1 (ET-1). The aim of the present study was to characterize the pericardial concentrations of the purine metabolites adenosine, inosine and hypoxanthine before and after intrapericardial administration of ET-1 to the in situ heart. The closed pericardial sac of anaesthetized dogs (n=9) was cannulated for ET-1 administration and for obtaining native pericardial fluid and control pericardial infusate samples (C1 and C2), as well as consecutive pericardial infusate samples (samples I, II and III) obtained 15 min after intrapericardial administration of 150 pmol/kg ET-1. In an additional five dogs, using the same protocol, ventricular epicardial and endocardial monophasic action potential recordings were performed to assess local ischaemic electrophysiological changes. Significant elevations of pericardial purine metabolite concentrations (measured by HPLC) were found in sample II compared with sample C2: adenosine, 4.5+/-1.7 compared with 0.5+/-0.1 microM (P<0.05); inosine, 18.3+/-2.8 compared with 0.9+/-0.2 microM (P<0.001); hypoxanthine, 38.1+/-8.0 compared with 13.4+/-2.6 microM (P<0.01). Systemic blood pressure, left ventricular pressure and contractility, and systemic plasma levels of the purine metabolites remained unchanged during the ET-1 effect, while significant ECG ST elevations (ST(max) 0.68+/-0.01 mV; P<0.001) were observed. In the five dogs analysed electrophysiologically, the left ventricular epicardial monophasic action potential duration and upstroke velocity decreased significantly at time point II compared with C2, while the endocardial monophasic action potential duration and upstroke velocity did not show ischaemia-related changes. The results suggest that intrapericardial administration of ET-1 induces subepicardial ischaemia, with parallel activation of coronary metabolic adaptive and cardiac self-protective mechanisms in the epimyocardial layer of the heart.

Increase in myocardial interstitial adenosine and net lactate production in brain-dead pigs: an in vivo microdialysis study.

Brain death-related cardiovascular dysfunction has been documented; however, its mechanisms remain poorly understood. We investigated changes in myocardial function and metabolism in brain-dead and control pigs. Heart rate, systolic (SAP) and mean (MAP) arterial pressure, left ventricular (LV) dP/dtmax, rate-pressure product, cardiac output (CO), left anterior descending coronary artery blood flow, lactate metabolism, and interstitial myocardial purine metabolite concentrations, monitored by cardiac microdialysis, were studied. A volume expansion protocol was performed at the end of the study. After brain death, a transient increase in heart rate (from 90 [67-120] to 158 [120-200] beats/min) (median, with range in brackets), MAP (82 [74-103] to 117 [85-142] mmHg), LV dP/dtmax (1750 [1100-2100] to 5150 [4000-62,000] mmHg x sec(-1), rate-pressure product (9100 [7700-9700] beats mmHg/min to 22,750 [20,000-26,000] beats mmHg/min), CO (2.2 [2.0-4.0] to 3.3 [3.0-6.0] L/min), and a limited increase in left anterior descending coronary artery blood flow (40 [30-60] to 72 [50-85] ml/min) were observed. Net myocardial lactate production occurred (27 [4-40] to -22 [-28, -11] mg/L, P<0.05) and persisted for 2 hr. A 6-7-fold increase in adenosine dialysate concentration was observed after brain death induction (2.9 [1.0-5.8] to 15.8 [7.0-50.7] micromol/L), followed by a slow decline. Volume expansion significantly increased MAP, CO, and LV dP/dtmax in control animals, but decreased LV dP/dtmax and slightly increased CO in brain-dead animals. A significant increase in adenosine concentration was observed in both groups, with higher levels (P<0.05) in brain-dead animals. Brain death increased oxygen demand in the presence of a limited increase in coronary blood flow, resulting in net myocardial lactate production and increased interstitial adenosine concentration consistent with an imbalance between myocardial oxygen demand and supply. This may have contributed to the early impairment of cardiac function in brain-dead animals revealed by rapid volume infusion.

Dual cardiac microdialysis to assess drug-induced changes in interstitial purine metabolites: adenosine deaminase inhibition versus adenosine kinase inhibition.

The purpose of this study was: 1) to evaluate a dual microdialysis technique coupled with local drug administration in the regionally ischemic rabbit heart, and; 2) to assess the ischemia-induced changes in interstitial fluid (ISF) adenosine during inhibition of adenosine deaminase or adenosine kinase. Two microdialysis probes were implanted parallel to each other and separated by 5 mm in myocardium perfused by a branch of the left coronary artery. Probes were used to sample myocardial ISF and to deliver drugs locally to the myocardium; purine metabolite concentrations in the collected dialysate were used as indices of ISF levels. Three groups of pentobarbital-anesthetized rabbits were studied. In a control group (n = 6), both probes were perfused with Krebs-Henseleit buffer. In the second and third groups, one probe was perfused with buffer, whereas the other probe was perfused with buffer containing 1 mM erythro-2-(2-hydroxy-3-nonyl)adenine (EHNA) (n = 5), an adenosine deaminase inhibitor, or 10 microM iodotubercidin (n = 9), an adenosine kinase inhibitor. All animals were exposed to 30 min of regional myocardial ischemia followed by 60 min of reperfusion. In the control group, similar increases in dialysate purine metabolites during ischemia were observed in both probes. Locally administered EHNA increased dialysate adenosine prior to ischemia and decreased dialysate inosine and hypoxanthine. During ischemia, the increase in dialysate adenosine in the EHNA-perfused probe was markedly augmented, while the increases in inosine and hypoxanthine were attenuated. In contrast, local infusion of iodotubercidin did not alter dialysate purine metabolites before ischemia, but there was a modest augmentation of adenosine during ischemia. These data illustrate the feasibility of dual microdialysis for assessing the effect of locally administered compounds on interstitial metabolite concentration in the regionally ischemic rabbit heart. Furthermore, adenosine deaminase inhibition has a more profound adenosine augmenting effect than adenosine kinase inhibition in the rabbit heart.

Purine metabolite concentrations in portal and peripheral blood of steers, sheep and rats

1. The concentration of purine derivatives in portal and peripheral blood of steers, sheep and rats was measured by reverse-phase high performance liquid chromatography. 2. Nucleotides, nucleosides (apart from inosine), adenine and guanine were not found in the plasma samples. Allantoin, uric acid, hypoxanthine and xanthine accounted for virtually all purine metabolites in plasma samples. 3. Non-oxidized derivatives (hypoxanthine and xanthine) were consistently detected in sheep but not in steer or rat plasma samples showing a differential availability of reutilizable purine derivatives between species.

Comparison of Cord Purine Metabolites to Maternal and Neonatal Variables of Hypoxia

Umbilical arterial concentrations of purine metabolites were evaluated prospectively as markers of hypoxia. The results suggest that hypoxanthine accumulates in association with fetal acidosis and reduced levels of buffer base (P less than .01). Acute hypoxemia defined by umbilical arterial oxygen pressure was accompanied by elevation of uric acid concentrations (P less than .01). Fetal heart rate tracings with characteristics classically associated with fetal stress correlated with increased concentrations of hypoxanthine and xanthine (P less than .01). Therefore, intrapartum events may occur that are not documented by standard markers of perinatal hypoxia at delivery.

55 BILATERAL PNEUMATHORAX (PTX) RESULTS IN INCREASED LEVELS OF PURINE METABOLITES IN PLASMA (P), CEREBRO-SPINAL FLUID (CSF) AND VITREOUS HUMOR (VH) OF NEWBORN PIGLETS

Hypoxanthine (HX), xanthine (X) and uric acid (U) levels were measured by HPLC technique in P, CSF and VH obtained from piglets during 4 hours of experimental PTX (Ret I.). 6 sham operated animals served as controls (Group I). The clinical and laboratory parameters wore in normal range during the experiments. In Group 2 (n=10), 59.3±3.9 min after the induction of PTX, in die critical phase (MABP=17.9±0.4 mmHg. HR=54.1±1.6 min−1, arterial pH=6.95±0.05. HCO3= 10.5±0.9 mMxL−1, pCO2=73±8 mmHg, pO2=29±3 mmHg. venous pH=6.93±0.04, CSF p11=7.13±0.04), after sampling of P and CSF, the piglets were resuscitated and a recovery period were allowed to them. P and CSF samples were also collected in 0., 120. and 240. minutes; while VH in 240. minutes of the experiments. HX reached its maximal concentration in P in the critical phase (53.8±7.8 μMxL−1 vs. the initial 18.8±3.6 μMxL−1, p<0.001). while in CSF it occurred only in the early reoxygenation period (120. min; 43.6±9.6 μMxL−1 vs. die initial 17.1 ±2.2 μMxL−1, p<0.01). X levels in P and CSF, and U concentrations in P increased gradually in the course of PTX indicating a conlinouos formation of these melabolites. There were elevations in the concentrations of purine metabolites in VH compared with the Group I [HX levels were 74.4±22.4 μMxL−1 vs. 48.2±18.9 μMxL−1 (N.S.), X levels 57.4±17.9 μMxL−1 vs. 21.4±8.6 μMxL−1 (N.S.) and U levels 150.0±39.9 μMxL−1 vs. 55.61±1.3 μMxL−1 (p<0.01), respectively.] In conclusion, elevaled levels of purine metabolites through die neonatal PTX indicating increased tissue damages due lo ihc formation of free radicals during posthypoxic-reoxygenalion period (Ref 2.). (All values are mean±SEM.)Refs: 1.TemesváriPetal.Ncurosci Lett 1990;113:163; 2.Saugstad OD, PediatrRes 1988-23:143.

100 PERSISTENT PRODUCTION OF HYPOXANTHINE IN RAT SKELETAL MUSCLE CAUSES PROLONGED HYPER —URICEMIA AFTER AN EXHAUSTIVE EXERCISE

In previus studies on exercise–induced hyperuricemia, we have reported that serum uric acid (UA) increases at 1–2 through 24 hours after an exhaustive exercise in human subjects, and that plasma oxypurine levels increase 1 through 7 hours after the end of an exhaustive exorcise in human subjects taking allopurinol. To study the mechanism of such prolonged exercise–induced hyperuricemia, we have used an animal model in this study. The maximal physical activity was enforced for 21 minutes on a treadmill to adult male Wislar rats to which allopurinol was administered beforehand. The concentrations of purine metabolites in plasma and muscle were assayed, by HPLC. Plasma UA was consistently low due to the administration of allopurinol. Plasma hypoxanthine (HX) and xanthine reached the peak, respectively, at 5 and 30 min, and they showed respectively, a higher tendency and a statistically higher level compared to the control rats without an exercise for 5 hours. In plantaris muscle, ATP decreased with increased IMP at 5 min. Inosine (Ino) increased significantly at 5 min and showed a higher tendency for I hour. HX increased significantly at 5 min through 2 hours. These data suggest that the production of HX from Ino in skeletal muscle persists after the end of an exhaustive exercise leading to the continuous release of HX lo blood for at least 2 hours. Based on these, it is concluded that persistent production of HX in skeletal muscle even after the end of an exhaustive exercise is responsible for prolonged exercise–induced hyperuricemia.

Determination of warm ischemia time at donor nephrectomy.

To assess the warm ischemia time of kidneys with obscure donor histories we attempted to develop an index for the duration of ischemia by analysis of adenine nucleotides and their degradation products in cortical biopsies of canine kidneys. Two biopsy harvesting techniques were compared. The use of a laboratory technique (dentist's drill) resulted in higher concentrations of adenosine triphosphate (ATP) in normoxic tissue specimens as compared with a clinical method of harvesting biopsies (wedge biopsy). However the sum of adenine nucleotides (AN) (ATP, adenosine diphosphate [ADP], and adenosine monophosphate [AMP]) was not significantly different in both groups (P less than 0.05). Therefore, wedge biopsies were used to study the degradation of AN following 0, 30, 60, 90, and 120 min of ischemia. Adenine nucleotides and their degradation products were assayed by high-performance liquid chromatography. Concentrations of individual adenine nucleotides did not show a consistent correlation with warm ischemia time. However, as the sum of the AN and the sum of their degradation products (DP) decreased and increased, respectively, the balance between these metabolites offered a good correlation with duration of warm ischemia. The ratio of DP to AN was significantly different at each interval (P less than 0.05). To study the influence of temperature on the degradation process, ischemia was induced at 37 degrees C and 32 degrees C. Lowering of the temperature reduced the catabolic rate of the AN. The ratio of DP to AN was significantly different from corresponding values at 37 degrees C. In biopsies of nonischemic human donor kidneys, concentrations of adenine nucleotides and their degradation products were measured. Biopsies weighing less than 0.01% of total renal mass were large enough to meet analytical demands. The ratio of DP to AN in human kidney biopsies was in the same range as in the corresponding dog kidney biopsies. These findings demonstrate that the ratio of DP to AN, as determined from concentrations of purine metabolites in canine cortical wedge biopsies, is a sensitive and potentially useful index of warm ischemia time.