Search results for "Acid-Base Equilibrium"
showing 10 items of 17 documents
Dependence of plasma pH on oxygen saturation
1969
Abstract The influence of haemoglobin oxygenation on the pH value of the blood plasma of healthy adolescents was investigated at 38°C by varying the parameters CO2 pressure, Hb concentration and buffer bases. A total of 5000 measurements gave the following results: 1. 1. The pHs difference between oxygenated and deoxygenated blood increases with diminishing CO2 pressure and with increasing Hb concentration. There is a linear relation between the pHs changes and the O2 saturation of the haemoglobin. 2. 2. Quantitatively these relationships can be expressed by the following equation: δpHs = (8 − pH ox − log 0.03 Pco 2 ) · [Hb] 225 · (100 − So 2 100 where ΔpHs is the pHs difference between par…
Urinary diversion in children and young adults using the Mainz Pouch I technique
1997
Objectives To determine the late complications and consequences for renal function, vitamin and acid-base metabolism after application of the Mainz Pouch I (MZP-I) technique in children and young adults. Patients and methods To November 1994, the MZP-I procedure was carried out in 463 patients at our institution, 91 of whom were children and adolescents (≤20 years old) using bladder augmentation in 21 and a continent cutaneous stoma in 70. A minimum follow-up of 1 year was possible in 87 patients or 163 renal units (RUs) with a mean of 5.5 years (range 1–10.5). Results At the last examination, 23 of 55 (42%) pre-operatively dilated RUs had improved, 131 of the 163 RUs (80%) were stable and …
Dietary acid load and renal function have varying effects on blood acid-base status and exercise performance across age and sex
2017
Diet composition influences acid-base status of the body. This may become more relevant as renal functional capacity declines with aging. We examined the effects of low (LD) versus high dietary acid load (HD) on blood acid-base status and exercise performance. Participants included 22 adolescents, 33 young adults (YA), and 33 elderly (EL), who followed a 7-day LD and HD in a randomized order. At the end of both diet periods the subjects performed a cycle ergometer test (3 × 10 min at 35%, 55%, 75%, and (except EL) until exhaustion at 100% of maximal oxygen uptake). At the beginning of and after the diet periods, blood samples were collected at rest and after all workloads. Oxygen uptake, r…
Body Composition and Power Performance Improved After Weight Reduction in Male Athletes Without Hampering Hormonal Balance
2014
The aim of this study was to investigate the effects of a 4-week weight reduction period with high protein and reduced carbohydrate intake on body composition, explosive power, speed, serum hormones, and acid-base balance in male track and field jumpers and sprinters. Eight participants were assigned to a high weight reduction group (HWR; energy restriction 750 kcal·d) and 7 to a low weight reduction group (LWR; energy restriction 300 kcal·d). Energy and carbohydrate intake decreased significantly (p ≤ 0.05) only in HWR by 740 ± 330 kcal·d and 130 ± 29 g·d, respectively. Furthermore, total body mass and fat mass decreased (p ≤ 0.05) only in HWR by 2.2 ± 1.0 kg and 1.7 ± 1.6 kg, respectively…
Effect of alkalosis on plasma epinephrine responses to high intensity cycle exercise in humans
2002
The purpose of this study was to determine the effects of alkalosis on epinephrine concentrations in response to a 90 s maximal exercise test. A group of ten healthy men ingested either a bicarbonate (BS) supplement (0.3 g x kg(-1) of body mass of sodium bicarbonate) or placebo mixture (P) prior to performing a 90 s maximal cycle ergometer test. An indwelling Teflon cannula was placed in the antecubital vein and blood samples were drawn at three times at rest separated by 10 min, immediately following the protocol, and at 2.5, 5, and 10 min post exercise to determine plasma epinephrine concentrations. Sodium bicarbonate ingestion significantly ( P0.05) induced alkalosis both at rest [mean (…
Minireview: pH and synaptic transmission
2013
AbstractAs a general rule a rise in pH increases neuronal activity, whereas it is dampened by a fall of pH. Neuronal activity per se also challenges pH homeostasis by the increase of metabolic acid equivalents. Moreover, the negative membrane potential of neurons promotes the intracellular accumulation of protons. Synaptic key players such as glutamate receptors or voltage-gated calcium channels show strong pH dependence and effects of pH gradients on synaptic processes are well known. However, the processes and mechanisms that allow controlling the pH in synaptic structures and how these mechanisms contribute to normal synaptic function are only beginning to be resolved.
Retention-pH profiles of acids and bases in hydrophilic interaction liquid chromatography
2018
Abstract The high proportion of acetonitrile used in many HILIC mobile phases significantly changes the acid-base properties of pH buffers and analytes foreseen from available data in water. In this paper, the recommended stability pH range for chromatographic columns is examined with various acetonitrile/water mixtures, resulting in a significant broadening in the operational pH window with the content of organic solvent. Additionally, the challenge of buffer selection in HILIC is also addressed. Commonly used ammonium acetate shrinks its pH buffering range in acetonitrile-rich mobile phases due to variations in the dissociation constants of the buffer constituents (acetic acid and ammoniu…
Effect of diet composition on acid–base balance in adolescents, young adults and elderly at rest and during exercise
2014
Diets rich in animal protein and cereal grains and deficient in vegetables and fruits may cause low-grade metabolic acidosis, which may impact exercise and health. We hypothesized that (1) a normal-protein diet with high amount of vegetables and fruits (HV) induces more alkaline acid-base balance compared with a high-protein diet with no vegetables and fruits (HP) and (2) diet composition has a greater impact on acid-base balance in the elderly (ELD).In all, 12-15 (adolescents (ADO)), 25-35 (young adults (YAD)) and 60-75 (ELD)-year-old male and female subjects (n=88) followed a 7-day HV and a 7-day HP in a randomized order and at the end performed incremental cycle ergometer tests. We inves…
Effects of 12-Week Low or Moderate Dietary Acid Intake on Acid–Base Status and Kidney Function at Rest and during Submaximal Cycling
2018
Prolonged effects of dietary acid intake on acid–base status and kidney function have not yet been studied in an intervention study in healthy subjects. Dietary acid load can be estimated by calculating the potential renal acid load (PRAL) of foods. Effects of low-PRAL and moderate-PRAL diets on acid–base status and kidney function were investigated during a 12-week exercise training period. Healthy, 20–50-year-old men (n = 21) and women (n = 25) participated in the study and were randomly divided into low-PRAL and moderate-PRAL groups. Before (PRE), mid-phase (MID) and after the intervention (POST), the subjects participated in measurement sessions, where a 12-h urine sample and fasting bl…
Oxygen-haemoglobin dissociation curve in hypoxic rats of first or second generation.
1993
SUMMARY 1. Albino Wistar rats were raised in a normobaric hypoxic environment (10% O2 in N2). Two generations of hypoxic rats were observed for changes in their haemoglobin-oxygen (Hb-O2) dissociation curves (ODC), 2,3-diphosphoglycerate (2,3-DPG), haemoglobin (Hb), and Hill coefficients at P50 (n50). The first generation were called (H1) and the second generation (H2). The control group (N) had a normoxic environment. 2. Thirty-five rats (13 N rats, 12 H1 rats and 10 H2 rats) were used. The 2,3-DPG was significantly higher in both hypoxic groups when compared with N rats (2.02 ± 0.51 mmol/L) but 2,3-DPG of H2 rats was significantly lower than that of H1 rats (H1 = 3.48±0.58 mmol/L and H2 =…