Search results for "Hydrogen-ion concentration"
showing 10 items of 769 documents
Exercise and recovery in frog muscle: metabolism of PCr, adenine nucleotides, and related compounds
1996
The effects of exercise (swimming), fatigue, and recovery on the intracellular pH (pHi), energy-rich phosphates, and related metabolites were studied in the gastrocnemius muscle of common frogs (Rana temporaria) at 20 degrees C. Exercise caused a rapid decrease in the content of phosphocreatine (PCr) and a corresponding increase in that of Pi. The ATP level remained virtually constant for 1 min; its precipitous decrease during the following minute was associated with a rise in the contents of inosine 5'-monophosphate (IMP) and NH4+, indicating a marked activation of AMP deaminase. Five minutes of swimming caused severe fatigue, which was correlated with decreases in muscle PCr (-85%), ATP …
[3H]-DA release evoked by low pH medium and internal H+ accumulation in rat hypothalamic synaptosomes: involvement of calcium ions
2003
The pH fluctuations have been often interpreted as an insufficient regulation or as a consequence of the onset of pathological events, such as ischemia, in which a significant decrease in pH levels occurs. Neurotransmitter release appears to be affected by pH drop significantly. In this study, we investigated the effect of an extracellular and an intracellular acidification on tritiated dopamine release ([3H]-DA release), from superfused rat hypothalamic synaptosomes. When compared to basal release, extracellular acidification, due to a reduction in the external pH of the nominally carbonic-free superfusion media, provoked a significant increase in [3H]-DA release that showed a sensitivenes…
Alpha 2-receptor-mediated inhibition of intraluminal release of gastric somatostatin in anaesthetized rats.
1992
Alino, S. F., Garcia, D. & Uvnas-Moberg, K. 1992. Alpha2-receptor-mediated inhibition of intraluminal release of gastric somatostatin in anaesthetized rats. Acta Physiol Scand144, 233–238. Received 22 February 1991, accepted 11 October 1991. ISSN 00014772. Department of Pharmacology and Pharmaceutics, University of Valencia, Valencia, Spain, Department of Cell Biology and Morphology Science, University of Pais Vasco, Leioa, Spain and Department of Pharmacology, Karolinska Institute, Stockholm, Sweden. The aim of the present study was to investigate how the sympathetic nervous system affects the vagally induced intragastric release of somatostatin and gastrin. Experiments were performed on a…
Gastroesophageal reflux in patients treated for congenital diaphragmatic hernia: short- and long-term evaluation with multichannel intraluminal imped…
2013
The incidence of GER, related symptoms and complications in patients treated for congenital diaphragmatic hernia (CDH) are poorly defined. The aim was to evaluate incidence and development of GER in children treated for CDH in a short- and long-term follow-up period, identifying potential risk factors of morbidity. Thirty-six patients were evaluated with pH-MII at a median age of 6 months (T1) and re-evaluated with pH-MII and endoscopy at a median age of 5 years (T2). The incidence of reflux was 83 % in T1 and 61 % in T2; the incidence of symptoms was 62 % in T1 and 38 % in T2. In both groups the reflux was mainly non-acidic. Patch, intrathoracic stomach and esophageal dysmotility were risk…
Variability in individual response to various doses of omeprazole. Implications for antiulcer therapy.
1994
This study was carried out in order to perform a combined prospective assessment of the individual pharmacodynamic response and of duodenal ulcer healing in patients treated with three different doses of omeprazole. Ninety-nine patients with endoscopically proven duodenal ulcers were subdivided into three parallel groups of 33 cases, who were randomly assigned to receive orally at 0800 hr, in single blind fashion, either 10 mg, 20 mg, or 40 mg of omeprazole. All of them underwent continuous intragastric pH monitoring both in basal conditions and on the fifth day of each dose regimen; ulcer healing was then assessed endoscopically after four weeks of treatment. All three doses of omeprazole …
Treatment Response in Patients with Stones, and Low Urinary pH and Hypocitraturia Stratified by Body Mass Index.
2015
Obesity has been shown to be a risk factor for kidney stone formation. Obesity leads to insulin resistance which subsequently leads to low urinary pH. Low urinary pH is typically treated with potassium citrate. We determined if the response to potassium citrate for the treatment of low urinary pH and hypocitraturia varied when patients were stratified by body mass index.We retrospectively reviewed the records of patients with urolithiasis and concomitant hypocitraturia and low urinary pH as unique abnormalities upon metabolic evaluation treated exclusively with potassium citrate. Based on body mass index the cohort was divided into the 4 groups of normal weight, overweight, obese and morbid…
Effect of Intraperitoneal Sterile Urine Injection on Abdominal Myoelectrical Activity in the Spinal Rat Model
1991
The abdominal muscle reflex contractions in response to intraperitoneal injection of homologous sterile urine and acid, alkaline, hypo- and hyperosmolar solutions are studied in an acute spinal rat model by conventional and integrated electromyographic techniques. Intraperitoneal injection of homologous sterile urine causes a powerful and almost immediate abdominal muscle contracture of relative short duration. This response seems not to be related to urine pH or osmolarity, since only when solutions with extreme variations in these parameters are injected intraperitoneally are significant abdominal muscle contractions observed.
Evaluation of esophageal motility and reflux in children treated for congenital diaphragmatic hernia with the use of combined multichannel intralumin…
2011
Abstract Background Gastroesophageal reflux (GER) is frequently observed in children treated for congenital diaphragmatic hernia (CDH) at birth, as well as esophageal dysmotility, that has been hypothesized to be caused by innervatory anomalies. The aim of this study is to evaluate GER and dysmotility in young patients with CDH using pH-multichannel intraluminal impedance. Methods Thirty children (17 boys and 13 girls) who underwent repair for CDH between 2002 and 2007 with a median age of 5.2 years (range, 3-10 years) were included in the study. All patients were operated on with a subcostal laparotomy incision and had a left-sided diaphragmatic defect. The defect repair required an artifi…
Exercise hyperventilation in chronic heart failure is not caused by systemic lactic acidosis
2005
Background: Patients with heart failure have an abnormally high ventilatory response to exercise associated with gas exchange defects and reduced arterial pCO2. Aims: We examined the possibility of lactic acidosis as the stimulus to this increased ventilation that abnormally depresses pCO2 during exercise in heart failure. Method and results: We studied 18 patients with chronic heart failure. We measured VE/VCO2 slope during exercise, arterial blood gases and lactate concentrations during cardiopulmonary exercise testing (rest, peak exercise and one minute after the end of exercise). Neither VE/VCO2 slope nor arterial pCO2 were related to arterial lactate concentrations at peak exercise (r=…
Binding of urate and caffeine to hemocyanin of the lobster Homarus vulgaris (E.) as studied by isothermal titration calorimetry.
2000
Hemocyanin serves as an oxygen carrier in the hemolymph of the European lobster Homarus vulgaris. The oxygen binding behavior of the pigment is modulated by metabolic effectors such as lactate and urate. Urate and caffeine binding to 12-meric hemocyanin (H. vulgaris) was studied using isothermal titration calorimetry (ITC). Binding isotherms were determined for fully oxygenated hemocyanin between pH 7.55 and 8.15. No pH dependence of the binding parameters could be found for either effector. Since the magnitude of the Bohr effect depends on the urate concentration, the absence of any pH dependence of urate and caffeine binding to oxygenated hemocyanin suggests two conformations of the pigme…