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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Samples of gastric juice were aspirated every 15 minutes from 54 normal subjects and 31 patients with chronic gastric ulcers during a maximal histamine infusion test. The known tendency of patients with gastric ulcers to secrete a less acid gastric juice than that of normal subjects was confirmed. However, the hypo-acidity was related to the extent by which the total ionic concentration was less than the isotonic value of 328 mEq/l. On the assumption that such hypo-acidity was produced by the neutralisation of hydrogen ions by bicarbonate ions refluxing into the stomach from the duodenum, the data were corrected and resulted in a normal estimate of the hydrogen ion concentration in the gastric ulcer group. Independent corrections, according to the sodium content of refluxed duodenal juice, yielded similar results for the volume of gastric juice aspirated. It is concluded that while back-diffusion can explain the hypo-acidity of gastric juice in patients with gastric ulcers, duodenal reflux can explain both the hypo-acidity and the hypotonicity, and is therefore more likely to be the correct explanation.
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PMID:Hypo-acidity of gastric juice in chronic gastric ulceration caused by neutralisation. 0 97

Pentagastrin has a distinct effect on the ratios of Na+,K+,H+/amino acid in the gastric juice in the different states of acidity. Contrary to the ratios of normacidity the values of all quotients in patients with hyper-, hypo- and anacidity are significantly reduced.
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PMID:[The influence of pentagastrin on the ratios of Na+,K+H+/Amino acids in gastric juice. Short communication (author's transl)]. 1 67

The inhibition of guinea-pig heart (Na+ + K+)-ATPase (ATP phosphohydrolase EC 3.6.1.3) by calcium has been studied at pH 7.4, 6.8 and 6.4. 1. A decrease in pH reduced the threshold inhibitory concentration of calcium and the calcium concentration producing an inhibition of 50% of the enzyme activity. 2. Calcium reduced the apparent affinity of the enzyme of Na+, this effect occurred only at pH 7.4. 3. Calcium increased the apparent affinity of the enzyme for K+, this effect was enhanced at acidic pH. 4. Activation of the enzyme by Na+ for a constant Na+ : K+ ratio has been studied at pH 7.4 and at pH 6.8 in the absence and in the presence of 3.10(-4) M Ca 2+; the results of this experiment indicate that Ca2+ effect at pH 7.4 was not influenced by Na+ -- K+ competition and was probably due to a Na+ -- Ca2+ interaction. 5. At pH 7.4, the calcium inhibitory threshold concentration and the concentration producing 50% inhibition were reduced when Na+ was low; at pH 6.8, the calcium inhibition was not markedly modified by the change of Na+ concentration. 6. The Ca2+ -activated ATPase of myosin B which is related to the contractile behaviour of muscle and the Ca2+ -ATPase of the sarcoplasmic reticulum which is related to the ability of this structure to accumulate calcium were activated in a range of calcium concentration producing an inhibition of (Na2+ + K+) -ATPase. The present results indicate that the increase by acidity of the (Na2+ + K+) -ATPase sensitivity to calcium might be due to a suppression of a Na+ -Ca2+ interaction. On the basis of these observations, it is proposed that calcium might inhibit the Na+ -pump during the repolarization phase of the action potential and that, by this effect, it might control cell excitability.
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PMID:Influence of pH and sodium on the inhibition of guinea-pig heart (Na+ + K+)-ATPase by calcium. 1 90

A sodium citrate preparation (Citro-Soda; Abbott) given in single doses of 4 or 12 g, satisfactorily increased the pH level of urine without affecting the systemic acid-base balance. When the sodium citrate preparation was administered in the 12-g single dose the gastric pH level was raised above 3,0 in a significant number of subjects. Similar results were obtained with both single doses (4 and 12 g) after 3 - 6 days of continuous therapy at the appropriate dose given every 6 hours. It is concluded that the urine-alkalinizing sodium citrate preparation reduced intragastric acidity significantly.
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PMID:Antacid properties of a sodium citrate preparation. 2 47

Metabolic acidosis is common in babies fed cows' milk-based formulae. Therefore the effects of adding alkaline salts (sodium and potassium citrate) to a demineralised whey formula were studied in vitro and in 26 low birthweight babies fed on the formula or formula plus citrate. The alkali altered the pH and titratable acidity to a value nearer human milk but it increased the buffering capacity to a value further away. This may effect the bacterial flora of the intestine. The babies fed on formula plus citrate did not make greater gains in weight, length, head circumference, skinfold thickness, or midarm muscle circumference, although they had a greater blood base excess. Some of these babies developed a mild metabolic alkalosis and 3 had hyponatraemia despite their increased sodium intakes. These babies also had lower levels of plasma transferrin but showed no differences in urea, albumin, cholesterol, and calcium levels. No baby fed on the demineralised whey formula without added citrate had a base deficit exceeding 5 mmol/l; late metabolic acidosis is less common in babies fed on this formula and the routine addition of alkali can have untoward metabolic effects.
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PMID:Milk pH, acid base status, and growth in babies. 3 63

A series of chromones containing an acidic group has been synthesized and screened for the ability to inhibit passive cutaneous anaphylaxis and the release of histamine from mast cells of the rat. Many of the chromones contain the N-(5-tetrazolyl)carboxamido group, a novel source of acidity. Others contain a carboxyl, C-(5-tetrazolyl), 5-(4H)-oxotetrazolinyl, or N-(5-tetrazolyl)sulfonamido function. The compounds were compared with cromolyn sodium (sodium cromoglycate) and many were found to be powerful inhibitors of anaphylaxis. The most potent was 7-methoxy-4-oxo-N-(5-tetrazolyl)-4H-1-benzopyran-2-carboxamide (15). Structure-activity relationships among the chromones and also some related compounds are discussed.
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PMID:Benzopyrones. 14. Synthesis and antiallergic properties of some N-tetrazolylcarboxamides and related compounds. 8 17

A "Batch" microcalorimeter is used at 30 degrees C for the study of the hydrolysis of 4-nitro-phenylphenylphosphonate with a calf-intestinal phosphonate esterase, in a tris buffer, pH 8. The yield of enzymatic hydrolysis is estimated by spectrophotometric determination of the p--nitrophenol evolved; we have then calculated the apparent molar enthalph of the reaction. (delta Happ = -72,2 kj. mol-1). Phenylphosphonic acid, the second reaction product, is not transphosphonylated on tris. The second acidity of phenylphosphonic acid was studied at 30 degrees C by sodium hydroxide electrotitration (pKa2 = 7,13) and by "Flow" microcalorimetry (delta Hionization = 19,8 kj.mol-1). In the same manner at 30 degrees C, we measured the heat of ionization of p-nitrophenol (delta Hionization = 26,75 kj.mol-1). These findings allow a calculation for the actual heat of hydrolysis of 4-nitro-phenyl-phenylphosphonate (delta Hrho = -29,7 kj.mol-1).
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PMID:[Study of the enzymatic hydrolysis of a phosphonic ester using microcalorimetry]. 23 63

An oral optimum therapeutic dose of poldine was established in 5 normal subjects. Acid secretion in response to a protein meal was measured for 3 hr by continuous intragastric titration with sodium bicarbonate. Poldine 30 min before the meal reduced food-stimulated acid secretion from zero to 60% in the 5 subjects (average inhibition 32%). Poldine inhibited histamine-stimulated acid secretion to approximately the same extent. In separate experiments, gastric acidity after the meal was allowed to seek its natural level (i.e., there was notitration with bicarbonate). Poldine reduced average hydrogen concentration of the gastric contents by 85 to 50% from 1.5 to 3 hr after the meal. Since poldine did not alter the volume or the buffer content of the stomach, poldine inhibition of gastric acidity is due entirely to reduction of acid secretion and not to delayed emptying of food buffer. Poldine had no consistent effect on serum gastrin concentration after the meal when pH was maintained at a constant level by titration with bicarbonate; therefore, poldine inhibition of acid secretion is not mediated by a reduction of serum gastrin concentration.
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PMID:Effect of optimum therapeutic dose of poldine on acid secretion, gastric acidity, gastric emptying, and serum gastrin concentration after a protein meal. 23 1

Rat studies demonstrated that low-pH powdered beverage mixes containing monocalcium phosphate caused less molar erosion than reconstituted frozen orange juice and grape juice when these beverages were consumed at excessive levels. A number of sodium phosphate supplements in low-pH beverages were not as effective as monocalcium phosphate in preventing molar erosion. Total acidity or pH values of the beverages could not be used with reliability to predict their potential to cause molar erosion.
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PMID:Effects of phosphates in acid-containing beverages on tooth erosion. 23 83

The effect of Jorpes secretin on the urinary volume, pH, and excretion of sodium, potassium, chloride, bicarbonate, titratable acidity, ammonia and phosphate was studied in five healthy male volunteers with and without simultaneous aspiration of duodenal fluids. A three- to fourfold increase in urinary volume and sodium excretion occurred within the first 30 min after secretin injection and this was accompanied by a significant rise in urinary pH in each instance. Urinary bicarbonate excretion increased from 55 plus or minus 13 to 395 plus or minus 33 mueq/30 min after secretin injection. Aspiration of alkaline duodenal contents was accompanied by an even greater postsecretin increase in urinary bicarbonate excretion. No significant changes in arterial pH or blood gases were detected throughout the study. These observations are compatible with a direct effect of secretin upon the renal tubular reabsorption of water, bicarbonate, and other ions, and could account for the transient alterations in urinary pH occurring in response to a meal.
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PMID:Renal response to secretin. 23 65


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