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PubMed1993

Enhanced HCO3 secretion by distal tubule contributes to NaCl-induced correction of chronic alkalosis.

Free-flow micropuncture studies show depressed net HCO3 reabsorption in the surface distal tubule of rats undergoing correction of chronic metabolic alkalosis induced by NaCl infusion. The present studies used in vivo microperfusion of the rat distal tubule to investigate whether the described reduction in net HCO3 reabsorption was due to decreased luminal H+ secretion or to increased HCO3 secretion. Animals with correcting alkalosis had higher HCO3 secretion in this nephron segment than did animals with maintained alkalosis regardless of whether the perfusing solution was initially Cl free (-27.6 vs. -16.6 pmol.mm-1.min-1, P < 0.01) or contained 40 mM Cl (-31.5 vs. -23.0 pmol.mm-1.min-1, P < 0.01); H+ secretion was not different between animals with correcting and maintained alkalosis. Animals without alkalosis (control) demonstrated no differences in H+ or HCO3 secretion in response to NaCl infusion. These studies demonstrate that enhanced HCO3 secretion mediates the depressed net HCO3 reabsorption observed in the distal tubule of rats undergoing NaCl-induced correction of chronic metabolic alkalosis.

Absorption↗
PubMed1999

Adaptation of NHE-3 in the rat thick ascending limb: effects of high sodium intake and metabolic alkalosis.

The present studies examined the effects of chronic NaCl administration and metabolic alkalosis on NHE-3, an apical Na+/H+ exchanger of the rat medullary thick ascending limb of Henle (MTAL). NaCl administration had no effect on NHE-3 mRNA abundance as assessed by competitive RT-PCR, as well as on NHE-3 transport activity estimated from the Na+-dependent cell pH recovery of Na+-depleted acidified MTAL cells, in the presence of 50 microM Hoe-694, which specifically blocks NHE-1 and NHE-2. Two models of metabolic alkalosis were studied, one associated with high sodium intake, i.e., NaHCO3 administration, and one not associated with high sodium intake, i.e., chloride depletion alkalosis (CDA). In both cases, the treatment induced a significant metabolic alkalosis that was associated with a decrease in NHE-3 transport activity (-27% and -25%, respectively). Negative linear relationships were observed between NHE-3 activity and plasma pH or bicarbonate concentration. NHE-3 mRNA abundance and NHE-3 protein abundance, assessed by Western blot analysis, also decreased by 35 and 25%, respectively, during NaHCO3-induced alkalosis, and by 47 and 33%, respectively, during CDA. These studies demonstrate that high sodium intake has per se no effect on MTAL NHE-3. In contrast, chronic metabolic alkalosis, regardless of whether it is associated with high sodium intake or not, leads to an appropriate adaptation of NHE-3 activity, which involves a decrease in NHE-3 protein and mRNA abundance.

Adaptation, Physiological↗
PubMed2005

Hypocapnic but not metabolic alkalosis impairs alveolar fluid reabsorption.

Acid-base disturbances, such as metabolic or respiratory alkalosis, are relatively common in critically ill patients. We examined the effects of alkalosis (hypocapnic or metabolic alkalosis) on alveolar fluid reabsorption in the isolated and continuously perfused rat lung model. We found that alveolar fluid reabsorption after 1 hour was impaired by low levels of CO2 partial pressure (PCO2; 10 and 20 mm Hg) independent of pH levels (7.7 or 7.4). In addition, PCO2 higher than 30 mm Hg or metabolic alkalosis did not have an effect on this process. The hypocapnia-mediated decrease of alveolar fluid reabsorption was associated with decreased Na,K-ATPase activity and protein abundance at the basolateral membranes of distal airspaces. The effect of low PCO2 on alveolar fluid reabsorption was reversible because clearance normalized after correcting the PCO2 back to normal levels. These data suggest that hypocapnic but not metabolic alkalosis impairs alveolar fluid reabsorption. Conceivably, correction of hypocapnic alkalosis in critically ill patients may contribute to the normalization of lung ability to clear edema.

Absorption↗
PubMed1968

Correction of metabolic alkalosis by the kidney after isomertric expansion of extracellular fluid.

Metabolic alkalosis was induced in dogs by administering ethacrynic acid and sustained by feeding a chloride-deficient diet. At the height of the alkalosis extracellular fluid was expanded "isometrically," i.e., with an infusion that duplicated plasma sodium, chloride, and bicarbonate concentrations. Correction of metabolic alkalosis promptly followed such expansion and was attributed to the selective retention by the kidneys of chloride from the administered solution. Since plasma chloride concentration was not increased as an immediate consequence of the infusion, it is concluded that the change in renal tubular function that led to the selective retention of chloride must have been mediated by factors independent of filtrate chloride concentration.A decrease in circulating mineralocorticoid level, as a consequence of volume expansion, does not seem to account for this change in tubular function since identical studies in dogs receiving excessive amounts of 11-deoxycorticosterone acetate during the day of infusion yielded similar findings. Moreover, no other consequence of volume expansion appears to be sufficient to cause this change in tubular function in the absence of metabolic alkalosis; when the alkalosis was corrected with hydrochloric acid before infusion, isometric expansion of extracellular volume did not induce selective chloride retention. We suggest that isometric expansion during metabolic alkalosis causes a decrease in proximal sodium reabsorption that relinquishes filtrate to a more distal site in the nephron and that this site may retain chloride preferentially when hypochloremia or chloride deficiency is present.

Acid-Base Equilibrium↗
PubMed1985

Alkalosis attenuates hypoxic pulmonary vasoconstriction in neonatal lambs.

Hyperventilation (respiratory alkalosis) is an important treatment for persistent pulmonary hypertension in neonates. The precise way that hyperventilation attenuates hypoxic pulmonary vasoconstriction is unclear. We studied the effect of alkalosis on hypoxia-induced pulmonary vasoconstriction in 13 acutely instrumented, pentobarbital anesthetized, neonatal lambs. We specifically examined the relative effects of a metabolic alkalosis versus a respiratory alkalosis on hypoxic pulmonary vasoconstriction and compared these results to the control response to hypoxia without alkalosis. Hypoxic pulmonary vasoconstriction was significantly milder whenever the animal was alkalotic, regardless of whether the alkalosis was respiratory of metabolic. Thus, the elevated pHa rather than decreased PaCO2 during hyperventilation appears to be the major factor in moderating the response of the pulmonary vessels to acute hypoxia in this neonatal lamb model.

Alkalosis, Respiratory↗
PubMed1988

Metabolic and blood catecholamine responses to exercise during alkalosis.

The effects of metabolic alkalosis on muscle lactate accumulation and plasma catecholamine concentrations were studied in six highly trained subjects during short-term ergocycle exercises to exhaustion (375 W). The studies were performed after oral administration of NaHCO3 (alkalosis) and CaCO3 (placebo). There was a significant increase in resting blood pH after NaHCO3 ingestion (7.35 +/- 0.02) compared to placebo (7.27 +/- 0.02). A longer endurance time was achieved during alkalosis (75.3 +/- 8 s) than during control (61.5 +/- 2 s), but similar blood pH and HCO3- levels were found at exhaustion in both treatments. Metabolic alkalosis resulted in higher elevation in muscle lactate concentration (31.7 +/- 4.6 mmol.kg-1 wet weight) compared to control (17 +/- 4 mmol.kg-1 wet weight). Despite longer exercise duration in alkalosis, plasma norepinephrine and epinephrine concentrations at exhaustion were reduced by 30 and 34%, respectively. These results indicate that alkalosis increased muscle lactate accumulation during exhaustive exercise. These changes were associated with a reduced blood catecholamine response to exercise.

Adult↗
PubMed1982

Compensatory hypoventilation in metabolic alkalosis.

Although hyperventilation is a well-known compensatory mechanism in metabolic acidosis, compensatory hypoventilation has been inconsistent and controversial in metabolic alkalosis. Six healthy subjects were studied under baseline conditions and during steady-state metabolic acidosis (seven episodes) and alkalosis (14 episodes). Minute ventilation (VE) fell in metabolic alkalosis and rose in metabolic acidosis. These changes in ventilation were entirely due to reduction and elevation of tidal volume (VT) respectively, while respiratory frequency (f) remained unchanged. Alveolar ventilation fell during metabolic alkalosis and resulted in elevation of arterial PCO2 in all subjects. The ventilatory response to arterial PCO2 in all subjects. The ventilatory response to CO2 breathing was also diminished. There was a linear relationship between PaCO2 and plasma [HCO-3] in metabolic acidosis and alkalosis which was defined as PaCO2 (mm Hg = 0.7 [HCO-a] + 20 (+/- SEM), r = 0.95. Although arterial PO2 and plasma [K+] fell during metabolic alkalosis, minute ventilation did not change upon breathing oxygen and there was no correlation between changes in plasma [K+] and plasma H+ regulation.

Acidosis↗
PubMed1985

Chronic heat stress and respiratory alkalosis: occurrence and treatment in broiler chicks.

The occurrence of respiratory alkalosis and potential benefit derived from treatment were examined in thermostressed 4-week-old broiler chicks. Blood pH was greater (P less than .05) in heat-stressed (32 C) panting birds (7.395) than either nonpanting (7.28) or birds raised at 24 C (7.28). Acute thermostress, obtained by elevating ambient temperature from 32 to 41 C over a 20-min period further elevated (P less than .05) blood pH to 7.521. Chronic heat-stressed broiler chicks suffer from intermittent respiratory alkalosis during panting; with acute heat stress, chicks pant continuously and suffer from alkalosis. Including .5% sodium bicarbonate (NaHCO3) in the diet of birds subjected to chronic heat stress enhanced body weight gain by 9% even though it tended (P less than .10) to increase blood pH in nonpanting birds. Adding .3 or 1% ammonium chloride (NH4Cl) to diets decreased blood pH (P less than .01) to 7.194 and increased (P less than .05) body weight gains by 9.5 and 25%, respectively. Effects appeared linear with NH4Cl dose to 1% NH4Cl, but 3% NH4Cl elevated weight gains by only 8% and precipitated blood acidosis (pH 7.09) in nonpanting birds. Supplementing the 1% NH4Cl diet with .5% NaHCO3 increased weight gains an additional 9%. Manipulating sodium: chloride ratios by addition of calcium chloride increased body weight gain 8% and slightly reduced severity of alkalosis. Data indicate that blood alkalosis limits growth rate of broiler chicks reared under chronic thermostress and that the respiratory alkalosis and weight gain depressions attributed to thermostress can be partially alleviated dietarily.

Alkalosis, Respiratory↗
PubMed2001

Metabolic alkalosis.

Metabolic alkalosis is a primary pathophysiologic event characterized by the gain of bicarbonate or the loss of nonvolatile acid from extracellular fluid. The kidney preserves normal acid-base balance by two mechanisms: bicarbonate reclamation, mainly in the proximal tubule, and bicarbonate generation, predominantly in the distal nephron. Bicarbonate reclamation is mediated mainly by a Na(+)-H(+) antiporter and to a smaller extent by the H(+)-ATPase (adenosine triphosphate-ase). The principal factors affecting HCO3(-) reabsorption include effective arterial blood volume, glomerular filtration rate, chloride, and potassium. Bicarbonate regeneration is primarily affected by distal Na(+) delivery and reabsorption, aldosterone, arterial pH, and arterial partial pressure of carbon dioxide. To generate metabolic alkalosis, either a gain of base or a loss of acid must occur. The loss of acid may be via the gastrointestinal tract or via the kidney. Excess base may be gained by oral or parenteral HCO3(-) administration or by lactate, acetate, or citrate administration. Factors that help maintain metabolic alkalosis include decreased glomerular filtration rate, volume contraction, hypokalemia, hypochloremia, and aldosterone excess. Clinical states associated with metabolic alkalosis are vomiting, mineralocorticoid excess, the adrenogenital syndrome, licorice ingestion, diuretic administration, and Bartter's and Gitelman's syndromes. The effects of metabolic alkalosis on the body are variable and include effects on the central nervous system, myocardium, skeletal muscle, and liver. Treatment of this disorder is simple, once the pathophysiology of the cause is delineated. Therapy consists of reversing the contributory factors that are promoting the alkalosis and, in severe cases, administration of carbonic anhydrase inhibitors, acid infusion, and low bicarbonate dialysis.

Alkalosis↗
PubMed2001

Respiratory alkalosis.

Respiratory alkalosis is an extremely common and complicated problem affecting virtually every organ system in the body. This article reviews the various facets of this interesting problem. Respiratory alkalosis produces multiple metabolic abnormalities, from changes in potassium, phosphate, and calcium, to the development of a mild lactic acidosis. Renal handling of the above ions is also affected. The etiologies may be related to pulmonary or extrapulmonary disorders. Hyperventilation syndrome is a common etiology of respiratory alkalosis in the emergency department setting and is a diagnosis by exclusion. There are many cardiac effects of respiratory alkalosis, such as tachycardia, ventricular and atrial arrhythmias, and ischemic and nonischemic chest pain. In the lungs, vasodilation occurs, and in the gastrointestinal system there are changes in perfusion, motility, and electrolyte handling. Therapeutically, respiratory alkalosis is used for treatment of elevated intracranial pressure. Correction of a respiratory alkalosis is best performed by correcting the underlying etiology.

Alkalosis, Respiratory↗
PubMedDate not supplied

Metabolic alkalosis.

Metabolic alkalosis is a primary pathophysiologic event characterized by the gain of bicarbonate or the loss of nonvolatile acid from extracellular fluid. The kidney preserves normal acid-base balance by two mechanisms: bicarbonate reclamation mainly in the proximal tubule and bicarbonate generation predominantly in the distal nephron. Bicarbonate reclamation is mediated mainly by a Na-H antiporter and to a smaller extent by the H-ATPase. The principal factors affecting HCO 3 reabsorption include effective arterial blood volume, glomerular filtration rate, chloride, and potassium. Bicarbonate regeneration is primarily affected by distal Na delivery and reabsorption, aldosterone, arterial pH, and arterial pCO2. To generate metabolic alkalosis, either a gain of base or a loss of acid, must occur. The loss of acid may be via the GI tract or by the kidney. Excess base may be gained by oral or parenteral HCO 3 administration or by lactate, acetate, or citrate administration. Factors that help maintain metabolic alkalosis include decreased glomerular filtration rate (GFR), volume contraction, hypokalemia, hypochloremia, and aldosterone excess. Clinical states associated with metabolic alkalosis are vomiting, mineralocorticoid excess, the adrenogenital syndrome, licorice ingestion, diuretic administration, and Bartter's and Gitelma's Syndromes. The effects of metabolic alkalosis on the body are varied and include effects on the central nervous system, myocardium, skeletal muscle, and the liver. Treatment of this disorder is simple, once the pathophysiology of the cause is delineated. Therapy consists of reversing the contributory factors promoting alkalosis and in severe cases, administration of carbonic anhydrase inhibitors, acid infusion, and low bicarbonate dialysis.

Acid-Base Equilibrium↗
PubMed1991

[The effect of metabolic alkalosis on colostrum and milk quality of cows and on the health status of their newborns].

The investigation was carried out on 12 cows and their calves. At the time of 3 months before parturition and 7 days after parturition metabolic alkalosis one provoked with the high protein feed. The laboratory investigations dependent of determinations on the rumen content the pH, NH3, volatile fatty, acids, the protozoa, bacteria, total gas CO2 and CH4. On the arterial and venous blood on determination the pH, BE, sO2, pO2, HCO3 and coefficient of consumption of the oxygen, and on the venous blood the levels of Na, K, Mg, Ca, P, total proteins, albumins and globulins, cholesterol, glucose, bilirubin, alkaline phosphatase and urea. In the colostrum and in milk one determined the pH, potential acidosis--degree SH, proper weight, proteins, dried mas of milk, time of coagulation in the presence of rennin, Na, K, Ca, Cl, total fats and their composition with different fatty acids. No existed truly changes of clinical signs, only feces was sickly. The metabolic alkalosis of cows decreased the consumption of oxygen across the tissue, deficient of the energy, disorders of water-electrolyte and acid-base balances. The calves form cows with metabolic alkalosis delivered also with metabolic alkalosis, with the symptoms of achondroplasia and degeneration of the liver and other organs. Metabolic alkalosis of cows influenced on the quality of colostrum and milk. The colostrum gained from cows with alkalosis caused of disturbance of gastrointestinal tract and diarrhea presence.

Alkalosis↗
PubMed1990

[Water-electrolyte and acid-base disorders. VII. Metabolic alkalosis].

Metabolic alkalosis is defined as a primary increase in plasma bicarbonate concentration. As a consequence of this increase, systemic alkalemia and secondary hypercapnia develop. In most instances metabolic alkalosis arises from loss of acid through the kidney or gastrointestinal tract. The causes of metabolic alkalosis can be separated into two groups. Those forms of alkalosis responsive to chloride salt administration (e.g., vomiting), are associated with extracellular fluid volume and chloride depletion. In contrast, alkalosis resistant to administration of chloride salt (e.g., primary aldosteronism), is usually associated with extracellular fluid volume expansion and a urine chloride above 20 mEq/L (mmol/L). Metabolic alkalosis; causes; diagnosis; clinical manifestations.

Alkalosis↗
PubMed1979

Hypoelectrolytemia and metabolic alkalosis in infants with cystic fibrosis.

The records of all children in the Tucson area diagnosed as having cystic fibrosis (CF) before the age of 12 months were reviewed to ascertain the prevalence of metabolic alkalosis as a major presenting manifestation of CF. Five of eleven infants (46%) in whom CF had been diagnosed between 1 and 12 months of age initially were seen with hypokalemia, hypochloremia, and metabolic alkalosis unassociated with marked dehydration, hyperpyrexia, or major pulmonary and/or gastrointestinal symptoms. Two infants had repeated episodes of metabolic alkalosis; for one of these infants, both episodes of metabolic alkalosis occurred before the diagnosis of CF. It is postulated that chronic loss of sweat electrolytes together with mild gastrointestinal or respiratory illness may predispose the infant with cystic fibrosis to a severe electrolyte and acid-base disturbance. The lack of shock and hyperpyrexia together with the apparent chronicity of electrolyte losses differentiates metabolic alkalosis from the heat prostration syndrome, a more acute complication of cystic fibrosis. Quantitative sweat testing should be part of the evaluation of any infant with unexplained metabolic alkalosis. Serum electrolytes should be assessed regularly in infants with cystic fibrosis during hot weather months.

Alkalosis↗
PubMed1980

[The question of "lactate alkalosis": animal experiments and a case report].

The intravenous infusion of sodium bicarbonate causes an alkalosis and an increase of lactate concentration in excess of 10 mmol/l in the experimental animal. The causal relation of alkalosis and lactic acidemia is also found in patients. A case of a therapy resistant alkalosis is demonstrated where a blood pH of 7.5 to 7.6 was correlated to a blood lactate concentration of 5 to 10 mmol/l. The normalisation of alkalosis was accompanied by a normalisation of lactate concentration to values of 1 to 2 mmol/l. The causal relation of alkalosis and increased blood lactate concentration seems to be obvious. We conclude that alkalosis is counteracted by a metabolic compensation due to the non volatile and lactic acid. Hyperlacticacidemia, therefore, is not identical with acidosis.

Alkalosis↗
PubMed1994

[Cystic fibrosis revealed by dehydration with hypochloronatremic alkalosis in 3 infants and a neonate].

BACKGROUND--Acute dehydration with hypochloronatremic metabolic alkalosis is a classical complication of cystic fibrosis of the pancreas. Its progressive development as a revealing manifestation of the disease is rare as is its appearance in newborns. Case n. 1.--A 13 month-old girl was admitted because of status epilepticus. She was severely dehydrated (20% weight loss) but had normal diuresis. Investigations showed metabolic alkalosis, hypochloronatremia and hypokalemia. All the manifestations disappeared within 5 days with treatment but three sweat tests were abnormal. Case n. 2.--A 7 month-old girl was admitted because she suffered from progressive loss of weight (10%); she was dehydrated and had metabolic alkalosis plus hypochloronatremia, but her diuresis was normal. Two sweat tests were abnormal. Case n. 3.--A 4.5 month-old boy was admitted because he suffered from severe (12%) weight loss. His diuresis was normal despite dehydration; metabolic alkalosis and hypochloronatremia were found. Two subsequent sweat tests were abnormal. Case n. 4.--A 3 day-old girl was admitted suffering from meconium ileus. Two initial mechanism analysis for protein were abnormal. She had a cardiorespiratory arrest on the 13th day of life, when she had lost 14% of her birth weight; investigations showed metabolic alkalosis, hyponatremia (83 mEq/l), hypochloremia (45 mEq/l); kalemia was 5.9 mEq/l. Peritoneal dialysis was needed to correct hydroelectrolytic changes. A sweat test performed on the 26th day of life was also abnormal. Investigations performed during the periods of dehydration, and repeated later, showed transient functional kidney failure. None of the four patients had any respiratory or gastrointestinal clinical manifestations of cystic fibrosis. CONCLUSION--Metabolic alkalosis with hypochloronatremia plus progressive, severe dehydration in infants whose diuresis is paradoxically normal must be followed by examination for cystic fibrosis.

Alkalosis↗
PubMed1997

Acute metabolic alkalosis in cystic fibrosis: prospective study and review of the literature.

Between January 1993 and April 1994, 5 patients with cystic fibrosis, aged 4-9 months, were admitted to the Department of Pediatrics, University of Berne, Switzerland, with acute, severe metabolic alkalosis (sodium < 133 mmol/l, plasma potassium < 3.5, chloride < 85, bicarbonate > 35.0 mmol/l, blood pH > 7.43). 87 cases of acute metabolic alkalosis complicating cystic fibrosis reported in the literature between 1951 and 1995 were also reviewed. Our cases and those described in the literature demonstrate that acute metabolic alkalosis occurs in patients aged 2 years or less. Anorexia, vomiting, respiratory exacerbation, fever, and body weight loss often precede metabolic alkalosis. Furthermore, metabolic alkalosis is a common initial presentation of cystic fibrosis, suggesting that this diagnosis should be considered in the context of unexplained metabolic alkalosis.

Acute Disease↗
PubMed1994

Alkalosis- and ATP-induced increases in the diacyglycerol pool in alveolar type II cells are derived from phosphatidylcholine and phosphatidylinositol.

Alkalosis and ATP increase surfactant secretion in alveolar type II cells, possibly via non-receptor- and receptor-mediated mechanisms respectively. We compared the effects of these two agonists on phosphatidylinositol (PI) and 1,2-diacylglycerol (DAG) pools and on phosphatidylcholine (PC) hydrolysis in alveolar type II cells. Alkalosis, caused by transfer of cells from 5% (control) to 0% CO2 in air, and ATP increased the secretion of surfactant compared with the controls. The stimulated secretion was inhibited by staurosporine, a protein kinase C inhibitor. DAG and PI contents of control cells were 50 +/- 1.1 (mean +/- S.E.M., n = 8) and 14 +/-0.8 nmol/mg phospholipid (n = 7) respectively. The DAG content increased by approximately 50 nmol (100%) within 5 s of treatment with both alkalosis and ATP, returned to control levels by 1 min, and increased again at 5 min by approximately 20 nmol. The PI content decreased maximally by approximately 6 nmol (40%) at 5 s and returned to control levels by 30 s with both alkalosis and ATP, but was unchanged thereafter. Mass-balance analysis of net changes in DAG and PI pools suggests that additional sources, possibly PC, must also contribute to the DAG increase. ATP or alkalosis also increased the hydrolysis of PC. The labelling of phosphocholine was increased (approximately 60%) at as early as 5 s and remained elevated at subsequent time points, whereas labelling of choline was higher only with ATP at 50 s and later, suggesting activation of phospholipase C by both agonists, and of phospholipase D by only ATP. Our studies demonstrate that ATP and alkalosis stimulate rapid hydrolysis of inositol and choline phospholipids to increase the DAG mass in type II cells, and that phospholipase C-stimulated PC hydrolysis is the major pathway for DAG formation.

Adenosine Triphosphate↗