Identification of compound mutations of SLC12A3 gene in a Chinese pedigree with Gitelman syndrome exhibiting Bartter syndrome-liked phenotypes.

BACKGROUND: Gitelman syndrome is a rare salt-losing renal tubular disorder associated with mutation of SLC12A3 gene, which encodes the Na-Cl co-transporter (NCCT). Gitelman syndrome is characterized by hypokalemia, metabolic alkalosis, hypomagnesemia, hypocalciuria, and renin-angiotensin-aldosterone system (RAAS) activation. Different SLC12A3 variants may lead to phenotypic variability and severity. METHODS: In this study, we reported the clinical features and genetic analysis of a Chinese pedigree diagnosed with Gitelman syndrome. RESULTS: The proband exhibited hypokalaemia, hypomagnesemia, metabolic alkalosis, but hypercalciuria and kidney stone formation. The increased urinary calcium excretion made it confused to Bartter syndrome. The persistent renal potassium wasting resulted in renal tubular lesions, and might affect urinary calcium reabsorption and excretion. Genetic analysis revealed mutations of SLC12A3 gene with c.433C > T (p.Arg145Cys), c.1077C > G (p.Asn359Lys), and c.1666C > T (p.Pro556Ser). Potential alterations of structure and function of NCCT protein due to those genetic variations of SLC12A3 are predicted. Interestingly, one sibling of the proband carried the same mutant sites and exhibited similar clinical features with milder phenotypes of hypokalemia and hypomagnesemia, but hypocalciuria rather than hypercalciuria. Family members with at least one wild type copy of SLC12A3 had normal biochemistry. With administration of spironolactone, potassium chloride and magnesium supplement, the serum potassium and magnesium were maintained within normal ranges. CONCLUSIONS: In this study, we identified compound mutations of SLC12A3 associated with varieties of clinical features. Further efforts are needed to investigate the diversity in clinical manifestations of Gitelman syndrome and its correlation with specific SLC12A3 mutations.

An unusual cause of metabolic alkalosis: hiding in plain sight.

BACKGROUND: Sodium bicarbonate, in the form of baking soda, is widely used as a home remedy, and as an additive for personal and household cleaning products. Its toxicity has previously been reported following oral ingestion in the setting of dyspepsia. However, its use as a non-ingested agent, like a toothpaste additive, has not been reported as a potential cause of toxicity. CASE PRESENTATION: We are reporting a case of an 80-year-old woman who presented with chronic metabolic alkalosis and hypokalemia secondary to exogenous alkali exposure from baking soda as a toothpaste additive, which might have represented an underreported ingestion of the substance. CONCLUSIONS: Considering that one teaspoon of baking soda provides approximately 59 m-equivalents (mEq) of bicarbonate, specific questioning on its general use should be pursued in similar cases of chloride resistant metabolic alkalosis.

Diagnóstico casual de un síndrome de Gitelman / Casual diagnosis of Gitelman's syndrome

El síndrome de Gitelman es una tubulopatía de herencia autosómica recesiva en el que la alteración fundamental se halla en el túbulo distal, concretamente a nivel del cotransportador Na/Cl, sensible a las tiazidas, codificado en el cromosoma 16q. Cursa con alcalosis metabólica con normotensión, hipopotasemia, así como hipomagnesemia e hipocalciuria que la diferencian del síndrome de Bartter. Su diagnóstico puede demorarse hasta la edad adulta ya que los pacientes pueden mantenerse asintomáticos durante largos períodos de tiempo. El tratamiento consiste en suplementos orales de potasio y magnesio, así como también se ha descrito la utilidad de diuréticos ahorradores de potasio e indometacina (AU)

Gitelman's syndrome is a renal tubule disease of recessive autosomal inheritance in which the fundamental alteration is found in the distal tubule, specifically at the level of the Na/Cl cotransporter, is sensitive to thiazides, and coded in chromosome 16q. It is characterised by a metabolic alkalosis with normal blood pressure, hypokalaemia, as well as hypomagnesaemia and hypocalciuria, which separate it from Bartter's syndrome. Its diagnosis can be delayed up to the adult age, as patients may remain asymptomatic for long periods of time. The treatment consists of oral supplements of potassium and magnesium, and the use of potassium-sparing diuretics and indomethacin has also been described (AU)

Síndrome de Bartter: avaliação do desenvolvimento estatural e perfil metabólico / Bartter's syndrome: evaluation of statural growth and metabolic profile

OBJETIVO: A síndrome de Bartter é uma doença rara, porém uma das mais frequentes condições congênitas perdedoras de cloro. Este trabalho teve como objetivo relatar a evolução de dez pacientes com a síndrome. MÉTODOS: Estudo observacional, descritivo, realizado pela análise de prontuários médicos relatando o perfil metabólico, a depuração de creatinina, o estado nutricional e pôndero-estatural de dez pacientes atendidos no Serviço de Nefrologia da Universidade Federal de São Paulo com características clínico-laboratoriais da síndrome de Bartter, seguidos por um período médio de 43 meses (3-76 meses). Durante o acompanhamento, o tratamento consistiu na administração de suplemento de potássio (100 por cento), magnésio (60 por cento), anti-inflamatórios não hormonais (90 por cento), inibidores de enzima conversora de angiotensina (40 por cento) e espironolactona (50 por cento). A análise estatística constou da comparação dos dados da primeira e da última consulta, utilizando-se o teste de Wilcoxon. RESULTADOSs: Observou-se melhora dos valores absolutos dos itens avaliados e do desenvolvimento pôndero-estatural com a terapêutica empregada, porém apenas a calemia [mediana inicial 3,05mEqL e final 3,25mEqL (p=0,01)] e o escore Z de peso idade [mediana inicial -2,47 e final -1,35 (p=0,02)] apresentaram melhora significante. Dos dez pacientes estudados, dois apresentavam diminuição da depuração de creatinina com doença renal crônica estágio 2 no final do acompanhamento (ambos tinham iniciado o acompanhamento com depuração renal comprometida). CONCLUSÕES: Há necessidade da instituição terapêutica precoce para melhorar os níveis séricos dos eletrólitos e o estado nutricional dos pacientes acometidos, sem comprometer a depuração de creatinina.

OBJECTIVE: Bartter's syndrome is one of the most important inherited diseases that cause chloride leak. The objective of this study was to report the follow-up of ten patients with the syndrome. METHODS: This observational study was based on the review of medical charts reporting the metabolic features, creatinine clearance, nutritional and anthropometric assessment of ten patients with Bartter's syndrome followed at the Nephrology Service of the Universidade Federal de São Paulo, in their first and last medical appointments, after a mean follow-up period of 43 months (3-76 months). During the follow-up, the management included the administration of potassium (100 percent) and magnesium (60 percent) supplements, non-steroidal anti-inflammatory agents (90 percent), angiotensin-converting enzyme inhibitors (40 percent) and spironolactone (50 percent). Statistical analysis was performed comparing the results of first versus last clinical appointment by non-parametric Wilcoxon test. RESULTS: Improvement of serum electrolytes and statural growth after the treatment was observed but only serum potassium [3.05mEq/L versus 3.25 mEq/L (p=0.01)] and weigh-for-age Z-score [initial median -2.47 versus -1.35 (p=0.02)] improved significantly. Out of the ten patients studied, two presented decrease of creatinine clearance with chronic kidney disease at stage 2 at the end of the follow-up. These patients had already started the follow-up with decreased creatinine clearance. CONCLUSIONS: There is a need of early treatment of patients with Bartter's syndrome in order to improve their electrolytes and nutritional condition without compromising the creatinine clearance.

OBJETIVO: El síndrome de Bartter (SB) es una enfermedad rara, pero una de las más frecuentes condiciones congénitas perdedoras de cloro. Este trabajo tiene por objetivo relatar la evolución de diez pacientes con SB. MÉTODOS: Estudio observacional, descriptivo, obtenido mediante análisis de prontuarios médicos. Relata el perfil metabólico, la depuración de creatinina, el estado nutricio-nal y ponderoestatural de los diez pacientes atendidos en el ambulatorio de Tubulopatías de Universidade Federal de São Paulo con características clínico-laboratoriales de SB, seguidos por un periodo mediano de 43 meses (3-76 meses). Durante el seguimiento se practicó protocolo de tratamiento que consistió en la administración de suplemento de potasio (100 por ciento), magnesio (60 por ciento), anti-inflamatorios no hormonales (90 por ciento), inhibidores de enzima convertidora de angiotensina (40 por ciento) y espironolactona (50 por ciento). Se consideraron criterios de exclusión la presencia de alteraciones séricas y urinarias no compatibles con SB. El análisis estadístico constó de la comparación de datos de la primera y la última consulta, utilizándose la prueba de Wilcoxon. RESULTADOS: Se observó mejora numérica de los valores absolutos de los ítems evaluados y del desarrollo ponderoestatural con la terapéutica utilizada, pero solamente la calemia [mediana inicial 3,05mEq/L y final 3,25mEq/L (p=0,01)] y el escore Z de peso/edad [mediana inicial -2,47 y final 1,35 (p=0,02)] presentaron mejora significante. De los 10 pacien-tes estudiados, dos presentaban reducción de la depuración de creatinina con enfermedad renal crónica etapa 2 y en el final del seguimiento (ambos habían iniciado el seguimiento con depuración renal comprometida). CONCLUSIONES: Los datos enfatizan la necesidad de la ins-titución terapéutica precoz para mejorar los niveles séricos de los electrólitos y el estado nutricional, sin comprometer la depuración de creatinina.

Effect of modified alkaline supplementation on bone metabolic turnover in rats.

This study aims to determine the effects of a high protein diet and alkaline supplementation on bone metabolic turnover in rats. Eight-week-old male Sprague-Dawley rats were investigated by bone status, including bone mineral density (BMD) and biomechanical markers from blood and urine. Thirty rats were randomly divided into three groups and treated for 8 weeks as follows: baseline control group (n. 10, C), high-protein supplemented diet group (n. 10, chronic acidosis, CA group) and supplemented chronic acidosis (n.10, SCA). Diet-treated rats were fed an acidic high-protein diet and the supplementation consisted in a modified alkaline formula (Basenpulver, NaMed, Italy). At the end of the experimental period, the rats were sacrificed, blood samples were drawn and femur and tibia were removed for analysis of bone mineral density (BMD) by dual energy X-ray absorptiometry (DEXA). In the CA group, 24-hour urinary calcium (Ca) and phosphorus (P) excretion were increased 2.1-fold (p<0.05 vs normal diet controls) as well as kidney weight. However, serum Ca and P concentration, as well as urinary Dpd excretion were not significantly changed. Femural and tibial BMD was significantly decreased in the CA group (p<0.05), but alkaline supplementation prevented such phenomenon (p<0.05 vs CA). These results suggest that blood Ca and P concentrations in chronic acidosis condition during the 12-week supplementation might be maintained by hypercalciuria and hyperphosphaturia at the expenses of bone structure. However, modified alkaline supplementation is able to prevent such derangements.

Brain pH response to hyperventilation in panic disorder: preliminary evidence for altered acid-base regulation.

OBJECTIVE: Previous findings of excess brain lactate and delayed end-tidal CO(2) (pCO(2)) recovery in subjects with panic disorder during hyperventilation suggested altered acid-base regulation. Two models were posited to explain these results: 1) subjects with panic disorder demonstrate greater alkalosis to hyperventilation, implicating increased lactate as directly compensatory, or 2) subjects with panic disorder demonstrate reduced or blunted alkalosis, implicating increased lactate as overly compensatory to a normal pH response. In both models, delayed pCO(2) recovery in subjects with panic disorder could reflect slower pH normalization in the recovery phase. METHOD: Asymptomatic medicated patients with panic disorder were studied during regulated hyperventilation. Phosphorous spectroscopy was used to measure brain pH every 2 minutes. Nine subjects with panic disorder were compared to 11 healthy subjects at baseline (five scans), during regulated hyperventilation (five scans), and across recovery (10 scans). Anxiety symptoms were assessed with standard ratings. RESULTS: No subject had a panic attack before hyperventilation. Subjects with panic disorder had lower pCO(2) during hyperventilation and slower pCO(2) recovery across the posthyperventilation interval. Despite this different respiratory response in the panic disorder group, brain pH increases were not significantly greater during hyperventilation, nor was pH return to baseline slowed during posthyperventilation. A linear regression model derived from data of healthy subjects showed pH blunting in the panic disorder group. CONCLUSIONS: Although subjects with panic disorder had greater hypocapnea during hyperventilation, their observed pH response, not altered from comparison levels, implicated exaggerated buffering. It is suggested that increased lactate could account for these findings.

Saline-resistant metabolic alkalosis, severe hypokalemia and hypertension in a 74-year-old woman.

The case of a 74-year-old woman with past history of hypertension and cerebrovascular accident admitted with pneumonia, dehydration, hypernatremia and severe hypokalemic alkalosis is presented. After correction of the hypertonic dehydration, the hypokalemia and alkalosis persisted in spite of aggressive potassium supplementation and the patient became hypertensive. Mineralocorticoid excess was suspected and excluded after extensive endocrinological testing. The use of aldactone failed to revert the abnormalities. Triamterene administration corrected the electrolytes and acid base aberrations, and dramatically improved the blood pressure control. This clinical picture is compatible with the diagnosis of Liddle's syndrome. Our patient exemplifies the unique occurrence of hypokalemic metabolic alkalosis in association with volume contraction at the start of the hospitalization and volume expansion later on her course.

pH regulation of K(+) efflux from myocytes in isolated rat hearts: (87)Rb, (7)Li, and (31)P NMR studies.

This study investigates the effects of intracellular (pH(i)) and extracellular pH (pH(e)) on the efflux of Rb(+) and Li(+) in isolated rat hearts. (87)Rb and (7)Li NMR were used to measure Rb(+) and Li(+) content, respectively, of hearts, and (31)P NMR was used to monitor pH(i), pH(e), and phosphate levels. After 30-min equilibration with Rb(+) or Li(+), effluxes were initiated by switching perfusion to a Rb(+)- or Li(+)-free, high-K(+) (20.7 mM) Krebs-Henseleit buffer with 15 microM bumetanide. Monensin (2 microM) increased pH(i) from 7.10 +/- 0.05 to 7.32 +/- 0.07 and resulted in activation of Rb(+) efflux; the first-order rate constant (k x 10(3), in min(-1)) increased from 42 +/- 2 to 116 +/- 16. Glibenclamide (4 microM) did not inhibit monensin-activated Rb(+) efflux (k = 110 +/- 17), whereas quinine (0.2 mM) slightly inhibited it by 19 +/- 9%. Infusion of 15 mM NH(4)Cl during Rb(+) washout increased k for Rb(+) efflux by 93% (81 +/- 8), which was glibenclamide and quinine insensitive, and caused a transient increase in pH(i) to 7.25 +/- 0.08. Intracellular Li(+) inhibited NH(4)Cl-stimulated Rb(+) efflux by 55%. Monensin and NH(4)Cl stimulated Li(+) efflux by 40%, increasing k from 29 +/- 3 to 43 +/- 7 and 41 +/- 3, respectively. The stimulation was not sensitive to 10 microM dimethylamiloride. Intracellular acidosis that resulted from the washout of NH(4)Cl (pH 6.86 +/- 0.2) slightly inhibited Rb(+) efflux (k = 36 +/- 5), whereas NH(4)Cl itself in the absence of pH(i) changes did not markedly affect Rb(+) efflux. A moderate increase in pH(i) (7.17 +/- 0.06) produced by washout of 15 mM 2, 2-dimethylpropionate (DMP)-Tris from hearts preequilibrated with DMP did not markedly affect Rb(+) efflux. Neither global alkalosis (pH(i) 7.4, pH(e) 7.55) nor acidosis (pH(i) approximately pH(e) 6.8) produced by 3 mM Tris base or 5 mM MES, respectively, affected Rb(+) efflux. We suggest that intracellular alkalosis stimulates Rb(+) (K(+)) and Li(+) effluxes by activating a nonselective sarcolemmal K(+) (Li(+))/cation exchanger or a K(+) (Li(+))-anion symporter.

Expression of colonic H-K-ATPase mRNA in cortical collecting duct: regulation by acid/base balance.

In addition to the gastric isoform of H-K-ATPase, the colonic isoform is also expressed in the kidney, but its intrarenal localization and exact function are not known. The goal of this study was to determine whether the colonic H-K-ATPase is expressed in the rabbit cortical collecting duct (CCD) and whether it is regulated by changes in acid/base balance. With quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) with RNA isolated from immunodissected rabbit CCD cells and degenerate oligonucleotide primers, a PCR product of the predicted size (approximately 430 bp) was amplified. The amplified DNA was further characterized by nested PCR and sequencing. Direct sequencing of the 434-bp PCR product revealed 83% identity at the nucleotide level and an 80.4% identity at the deduced amino acid level to the rat colonic H-K-ATPase. With the same primers and cDNA originating from rabbit distal colon, a DNA fragment with a size and nucleotide sequence identical to that originating from CCD cells was amplified. Furthermore, using PCR screening, we isolated and sequenced a 1.5-kb cDNA clone from a rabbit CCD library. The predicted amino acid sequence of the protein encoded by this cDNA is 85 and 82% identical to the corresponding regions of the guinea pig and rat colonic H-K-ATPase, respectively, and 70% identical to the H-K-ATPase recently cloned from Bufo marinus, whereas it shows only 45 and 42% homology to the rat Na-K-ATPase alpha 1-subunit and the rat gastric H-K-ATPase, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Transepithelial pH gradients in cortical distal tubules during metabolic alkalosis.

1. The cortical distal tubule of the rat kidney participates in the regulation of acid-base balance, showing bicarbonate reabsorption, secretion or absence of transport under different experimental conditions. In the present study, we measured differences in transepithelial pH using double ion-exchange resin/reference microelectrodes in control and alkalotic (chronic plus acute) male Wistar rats and in alkalotic rats receiving a K+ supplement in diet and infusion. 2. pH was measured in the tubule lumen during stationary microperfusion with 25 mM bicarbonate Ringer solution, and in peritubular vessels next to the perfused tubules. 3. Differences in transepithelial pH were 0.70 +/- 0.12 (N = 16) pH units in early distal tubules (ED) and 1.03 +/- 0.050 (N = 15) in late distal tubules LD) of control rats, 0.22 +/- 0.056 (N = 17) in ED and 0.25 +/- 0.050 (N = 20) in LD of alkalotic rats, and -0.02 +/- 0.039 (N = 24) in ED and -0.02 +/- 0.040 (N = 24) in LD of K(+)-supplemented alkalotic rats. 4. In control rats, the transepithelial potential difference (PD) (-8.9 +/- 1.45 mV (N = 16) in ED and -32.7 +/- 2.99 mV (N = 15) in LD) was not large enough to explain transepithelial H+ and HCO3- gradients, suggesting the presence of an active transport mechanism responsible for their maintenance. 5. The present data show that the cortical distal tubule is able to establish transepithelial pH (HCO3-) differences, that these differences are reduced by alkalosis and abolished by alkalosis plus K+ supplementation, and that, although inversion of pH gradients (evidence for bicarbonate secretion) was observed in individual tubules, this inversion was not significant in the groups studied.

Transepithelial pH gradients in cortical distal tubules during metabolic alkalosis

1. The cortical distal tubule of the rat kidney participates in the regulation of acid-base balance, showing bicarbonate reabsorption, secretion or absence of transport under different experimental conditions. In the present study, we measured differences in transepithelial pH using double ion-exchange resin/reference microelectrodes in control and alkalotic (chronic plus acute) male Wistar rats and in alkalotic rats receiving a K+ supplement in diet and infusion. 2. pH was measured in the tubule lumen during stationary microperfusion with 25 mM bicarbonate Ringer solution, and in peritubular vessels next to the perfused tubules. 3. Differences in transepithelial pH were 0.70 +/- 0.12 (N = 16) pH units in early distal tubules (ED) and 1.03 +/- 0.050 (N = 15) in late distal tubules LD) of control rats, 0.22 +/- 0.056 (N = 17) in ED and 0.25 +/- 0.050 (N = 20) in LD of alkalotic rats, and -0.02 +/- 0.039 (N = 24) in ED and -0.02 +/- 0.040 (N = 24) in LD of K(+)-supplemented alkalotic rats. 4. In control rats, the transepithelial potential difference (PD) (-8.9 +/- 1.45 mV (N = 16) in ED and -32.7 +/- 2.99 mV (N = 15) in LD) was not large enough to explain transepithelial H+ and HCO3- gradients, suggesting the presence of an active transport mechanism responsible for their maintenance. 5. The present data show that the cortical distal tubule is able to establish transepithelial pH (HCO3-) differences, that these differences are reduced by alkalosis and abolished by alkalosis plus K+ supplementation, and that, although inversion of pH gradients (evidence for bicarbonate secretion) was observed in individual tubules, this inversion was not significant in the groups studied

Acid-base regulation of hepatic glutamine metabolism and ureagenesis: study with 15N.

The metabolism of (5-15N)glutamine and (2-15N) glutamine has been studied by isolated hepatocytes obtained from either control, chronically acidotic, or alkalotic rats. The main goal was to elucidate the mechanism(s) by which altered acid-base state affects hepatic ureagenesis from glutamine. Isolated hepatocytes were incubated in Krebs buffer (pH 7.4) supplemented with 0.1 mM ornithine plus either 1 mM (5-15N)glutamine or (2-15N)glutamine. To elucidate the role of glutamine cycling in net ammonia metabolism, a separate series of experiments were performed with 1 mM unlabeled glutamine plus 1 mM (15N)H4Cl. Net glutamine utilization was significantly lower in hepatocytes obtained from chronically acidotic rats compared with control or alkalotic rats. The sum of the rates of 15NH3 and (15N)urea production from (5-15N)glutamine was decreased in acidosis compared with alkalosis. After incubations of 50 min, approximately 75, 65, or 90% of the N in carbamoyl-phosphate was derived from the 5-N of glutamine in control, acidosis, or alkalosis respectively. In experiments with (2-15N)glutamine, the production of singly and doubly labeled (15N)urea as well as (15N)aspartate and (15N)H3 was significantly smaller in acidosis compared with alkalosis. Furthermore, a correlation was observed between production rates of (15N)aspartate and (15N)urea, suggesting that alterations in urea production may depend on aspartate formed from glutamine. However, the production of (15N)alanine was higher in acidosis compared with alkalosis with apparent correlation between the production of (15N)alanine and 2-oxoglutaramate, a product of the glutamine aminotransferase pathway. In addition, the rate of glutamine recycling was significantly higher in acidosis compared with control or alkalosis, indicating that both flux through glutamine aminotransferase and flux through glutamine synthetase were elevated in acidosis compared with alkalosis. These data suggest that decreased formation of aspartate from glutamine may limit ureagenesis in chronic metabolic acidosis. The formation of aspartate may depend on the availability of oxaloacetate rather than diminished flux through transaminase reaction. The enhancement of alanine production and glutamine synthesis may provide an alternate route of N disposal in cases of diminished urea formation.

Elevated lactate and alkalosis in chronic human brain infarction observed by 1H and 31P MR spectroscopic imaging.

The goal of this study was to investigate lactate and pH distributions in subacutely and chronically infarcted human brains. Magnetic resonance spectroscopic imaging (MRSI) was used to map spatial distributions of 1H and 31P metabolites in 11 nonhemorrhagic subacute to chronic cerebral infarction patients and 11 controls. All six infarcts containing lactate were alkalotic (pHi = 7.20 +/- 0.04 vs. 7.05 +/- 0.01 contralateral, p less than 0.01). This finding of elevated lactate and alkalosis in chronic infarctions does not support the presence of chronic ischemia; however, it is consistent with the presence of phagocytic cells, gliosis, altered buffering mechanisms, and/or luxury perfusion. Total 1H and 31P metabolites were markedly reduced (about 50% on average) in subacute and chronic brain infarctions (p less than 0.01), and N-acetyl aspartate (NAA) was reduced more (approximately 75%) than other metabolites (p less than 0.01). Because NAA is localized in neurons, selective NAA reduction is consistent with pathological findings of a greater loss of neurons than glial cells in chronic infarctions.

Decreased phosphorus metabolite concentrations and alkalosis in chronic cerebral infarction.

A study was performed to determine quantitatively the alterations in phosphorus metabolite concentrations and pH in regions of the human brain damaged by chronic stroke. Image-guided phosphorus-31 magnetic resonance spectroscopy was performed on the brains of eight healthy subjects and six patients with cerebral infarction of more than 3 months duration. Phosphorus metabolite concentrations in infarcted regions were reduced 8%-67%. Significant decreases occurred in phosphomonoester (PME), phosphodiester (PDE), and adenosine triphosphate (ATP) concentrations, while inorganic phosphate (Pi) and phosphocreatine (PCr) concentrations showed smaller, nonsignificant decreases. The PCr/ATP ratio was significantly increased, while the ATP/Pi ratio was somewhat lower. The phospholipid ratio PDE/PME was also significantly increased, while the ratios of phospholipid (PME, PDE) to phosphate (PCR, Pi) metabolites were significantly decreased. The pH of the infarcted region indicated significantly more alkalinity than in the normal brain. The results suggest that chronic stroke is associated with significant changes in brain metabolite concentrations and pH that are different from those reported for other brain diseases.

Effect of magnesium depletion and potassium depletion and chlorothiazide on intracellular pH in the rat, studied by 31P NMR.

1. Both dietary magnesium depletion and potassium depletion (confirmed by tissue analysis) were induced in rats which were then compared with rats treated with chlorothiazide (250 mg/kg diet) and rats on a control synthetic diet. 2. Brain and muscle intracellular pH was measured by using a surface coil and [31P]-NMR to measure the chemical shift of inorganic phosphate. pH was also measured in isolated perfused hearts from control and magnesium-deficient rats. Intracellular magnesium status was assessed by measuring the chemical shift of beta-ATP in brain. 3. There was no evidence for magnesium deficiency in the chlorothiazide-treated rats on tissue analysis or on chemical shift of beta-ATP in brain. Both magnesium and potassium deficiency, but not chlorothiazide treatment, were associated with an extracellular alkalosis. 4. Magnesium deficiency led to an intracellular alkalosis in brain, muscle and heart. Chlorothiazide treatment led to an alkalosis in brain. Potassium deficiency was associated with a normal intracellular pH in brain and muscle. 5. Magnesium depletion and chlorothiazide treatment produce intracellular alkalosis by unknown mechanism(s).

Effects of acid-base status and fluoride on the composition of the mineral in developing enamel and dentine in the dog.

Developing molar teeth of the dog were sectioned, embedded in copper containing polymethyl methacrylate, polished and their Ca/P and Ca/Na molar ratios investigated with the electron microprobe. The teeth were obtained at 30 days from 9 pups fed regimes of different acid-base status with or without fluoride supplementation from birth to sacrifice at 30 days. No clear trends in their Ca/P or Ca/Na ratios with variation in the diet were observed. However, evaluation of the Ca/P ratio of the enamel as a function of depth revealed that this ratio was 0.80 +/- 0.15 at the mineralization front. This suggests that in enamel brushite rather than octacalcium phosphate is the precursor phase of the mineral.

Renal tissue metabolism in the rat during chronic metabolic alkalosis: importance of glycolysis.

Chronic metabolic alkalosis was induced in rats drinking 0.3 M NaHCO3 and receiving 1 mg furosemide/100 g body weight per day intraperitoneally. Another group of animals received a potassium supplement in the form of 0.3 M KHCO3. In this group, hypokalemia did not develop and muscle potassium fell by only 18% versus 50% in those not receiving potassium. In vitro renal production of ammonia and uptake of glutamine fell by 40% with a decrease in the activity of glutaminase I and glutamate dehydrogenase. Activity of phosphofructokinase, a major enzyme of glycolysis, rose only in the kidney of animals receiving a potassium supplement. Fructose-1,6-diphosphatase fell as well as phosphoenolpyruvate carboxykinase. Malate dehydrogenase also fell. The activity of phosphofructokinase also rose in the liver, heart, and leg muscle. The major biochemical changes in the renal cortex were the following: glutamate, alpha-ketoglutarate, malate, lactate, pyruvate, alanine, aspartate, and citrate rose as well as calculated oxaloacetate. The concentration of intermediates like 2-phosphoglycerate, 3-phosphoglycerate, and glucose-6-phosphate fell. The cytosolic redox potential (NAD+/NADH) decreased. In addition to the fall in ammoniagenesis, it could be demonstrated in vitro that the renal tubules incubated with glutamine showed decreased glucose production and increased production of lactate and pyruvate. The concentration of lactate was elevated in all tissues examined including liver, heart, and leg muscle. This study confirms in the rat that decreased renal ammoniagenesis takes place following decreased uptake of glutamine in metabolic alkalosis. All other changes are accounted for by the process of increased glycolysis, which appears to take place in all tissues in metabolic alkalosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Pseudohyperaldosteronism (Liddle's syndrome): a case report.

A 22-year-old man was hospitalized because of hypertension, hypokalemic alkalosis and suppressed plasma renin activity. Although these findings were similar to hyperaldosteronism, plasma aldosterone concentration and urinary aldosterone excretion were lower than the normal range. Adrenocortical function also was normal except for aldosterone. Treatment with spironolactone, salt restriction and potassium supplementation improved the hypokalemia but not the hypertension. Blood pressure decreased markedly after administration of triamterene.

Renal tubular biochemistry during acute and chronic metabolic alkalosis in the dog.

Acute metabolic alkalosis was induced in dogs by the infusion of sodium bicarbonate, 0.3 M. Chronic alkalosis was induced by chloride restriction and the administration of sodium bicarbonate and furosemide. In a third group of dogs, potassium was added to the regimen to prevent frank potassium depletion. Plasma bicarbonate ranged from 29.0 to 32.9 mM. In all three dog groups, renal ammoniagenesis fell by over 30%, which was consistent with a decrease in the renal uptake of glutamine. Glutamate was released in the renal vein and alanine production was decreased. Total production of ammonia was lowest in the animals given a potassium supplement where muscle potassium decreased much less than in the other chronic animals. Urinary ammonia excretion was very low in all three animal groups; this was related to an alkaline urine. However, this relationship was not entirely consistent and the low excretion of ammonia could also be related to decreased ammonia production by the renal tubular cell. In the renal cortical tissue (freeze-clamped), the concentration of glutamate did not change and that of alpha-ketoglutarate rose only in the animals supplemented with potassium. Malate rose in all groups. In all animals, renal tissue concentration of lactate and citrate rose while citrate excretion increased. We feel that glycolysis could play an important role in renal metabolism during acute and chronic metabolic alkalosis. We have proposed a unified theory to explain the metabolic changes that occur in lactate and citrate metabolism during metabolic alkalosis with a depressing effect on ammoniagenesis. Although citrate could be generated in the mitochondria from pyruvate, its oxidation is probably inhibited with exit and accumulation in the cytosol.

Blood pH and brain uptake of 14C-morphine.

14C-Morphine was injected iv in control awake rats or in rats subjected to metabolic alkalosis or acidosis. Ten minutes later, radioactivity was determined within each of seven brain regions, after correction was made for intravascular tracer. In each region, parenchymal radioactivity was correlated positively and significantly (P less than 0.05) with arterial blood pH. Brain radioactivity was twofold to threefold greater in alkalotic rats (mean pH = 7.62) than in acidotic rats (mean pH = 7.16). The results are consistent with the pH-partition hypothesis for drug entry into the brain and indicate that morphine uptake can be increased by elevating the fraction of lipid-soluble uncharged morphine base in blood, by means of alkalosis. The observations may account for an exaggerated morphine-induced analgesia in alkalotic patients.