Role of anions in metabolic alkalosis and potassium deficiency

"I don't get no respect": the role of chloride in acute kidney injury

Acute kidney injury (AKI) is a major public health problem that complicates 10-40% of hospital admissions. Importantly, AKI is independently associated with increased risk of progression to chronic kidney disease, end-stage renal disease, cardiovascular events, and increased risk of in-hospital and long-term mortality. The chloride content of intravenous fluid has garnered much attention over the last decade, as well as its association with excess use and adverse outcomes, including AKI. Numerous studies show that changes in serum chloride concentration, independent of serum sodium and bicarbonate, are associated with increased risk of AKI, morbidity, and mortality. This comprehensive review details the complex renal physiology regarding the role of chloride in regulating renal blood flow, glomerular filtration rate, tubuloglomerular feedback, and tubular injury, as well as the findings of clinical research related to the chloride content of intravenous fluids, changes in serum chloride concentration, and AKI. Chloride is underappreciated in both physiology and pathophysiology. Although the exact mechanism is debated, avoidance of excessive chloride administration is a reasonable treatment option for all patients and especially in those at risk for AKI. Therefore, high-risk patients and those with "incipient" AKI should receive balanced solutions rather than normal saline to minimize the risk of AKI.

Mechanism of Hyperkalemia-Induced Metabolic Acidosis

Background Hyperkalemia in association with metabolic acidosis that are out of proportion to changes in glomerular filtration rate defines type 4 renal tubular acidosis (RTA), the most common RTA observed, but the molecular mechanisms underlying the associated metabolic acidosis are incompletely understood. We sought to determine whether hyperkalemia directly causes metabolic acidosis and, if so, the mechanisms through which this occurs.Methods We studied a genetic model of hyperkalemia that results from early distal convoluted tubule (DCT)-specific overexpression of constitutively active Ste20/SPS1-related proline-alanine-rich kinase (DCT-CA-SPAK).Results DCT-CA-SPAK mice developed hyperkalemia in association with metabolic acidosis and suppressed ammonia excretion; however, titratable acid excretion and urine pH were unchanged compared with those in wild-type mice. Abnormal ammonia excretion in DCT-CA-SPAK mice associated with decreased proximal tubule expression of the ammonia-generating enzymes phosphate-dependent glutaminase and phosphoenolpyruvate carboxykinase and overexpression of the ammonia-recycling enzyme glutamine synthetase. These mice also had decreased expression of the ammonia transporter family member Rhcg and decreased apical polarization of H⁺-ATPase in the inner stripe of the outer medullary collecting duct. Correcting the hyperkalemia by treatment with hydrochlorothiazide corrected the metabolic acidosis, increased ammonia excretion, and normalized ammoniagenic enzyme and Rhcg expression in DCT-CA-SPAK mice. In wild-type mice, induction of hyperkalemia by administration of the epithelial sodium channel blocker benzamil caused hyperkalemia and suppressed ammonia excretion.Conclusions Hyperkalemia decreases proximal tubule ammonia generation and collecting duct ammonia transport, leading to impaired ammonia excretion that causes metabolic acidosis.

Treatment of Severe Metabolic Alkalosis with Continuous Renal Replacement Therapy: Bicarbonate Kinetic Equations of Clinical Value

Concomitant severe metabolic alkalosis, hypernatremia, and kidney failure pose a therapeutic challenge. Hemodialysis to correct azotemia and abnormal electrolytes results in rapid correction of serum sodium, bicarbonate, and urea but presents a risk for dialysis disequilibrium and brain edema. We describe a patient with Zollinger-Ellison syndrome with persistent encephalopathy, severe metabolic alkalosis (highest bicarbonate 81 mEq/L), hypernatremia (sodium 157 mEq/L), and kidney failure despite 30 hours of intravenous crystalloids and proton pump inhibitor. We used continuous renal replacement therapy (RRT) with delivered hourly urea clearance of ~3 L/hour (24 hour sustained low efficiency dialysis with regional citrate anticoagulation protocol at blood flow rate 60 ml/min and dialysate flow rate 400 ml/min). To mitigate a pronounced decrease in plasma osmolality while removing urea from this hypernatremic patient, dialysate sodium was set to start at 155 mEq/L then at 150 mEq/L after 6 hours. Serum bicarbonate, urea, and sodium were slowly corrected over 26 hours. This case demonstrates how to regulate and predict the systemic bicarbonate level using single pool kinetic modeling during convective or diffusive RRT. Kinetic modeling provides a valuable tool for systemic blood pH control in future combined use of extracorporeal CO2 removal and continuous RRT systems.

It is chloride depletion alkalosis, not contraction alkalosis

Maintenance of metabolic alkalosis generated by chloride depletion is often attributed to volume contraction. In balance and clearance studies in rats and humans, we showed that chloride repletion in the face of persisting alkali loading, volume contraction, and potassium and sodium depletion completely corrects alkalosis by a renal mechanism. Nephron segment studies strongly suggest the corrective response is orchestrated in the collecting duct, which has several transporters integral to acid-base regulation, the most important of which is pendrin, a luminal Cl/HCO(3)(-) exchanger. Chloride depletion alkalosis should replace the notion of contraction alkalosis.

Long-term combined treatment with thiazide and potassium citrate in nephrolithiasis does not lead to hypokalemia or hypochloremic metabolic alkalosis

BACKGROUND

Potassium citrate is commonly used in combination with a thiazide diuretic in the medical management of recurrent hypercalciuric nephrolithiasis. However, concerns have been raised that administration of this nonchloride potassium alkali with a kaliuretic and natriuretic agent such as thiazide may not be efficacious in correcting or preventing hypokalemia, and may produce hypochloremic metabolic alkalosis. This retrospective analysis was conducted to determine if these two potential complications are encountered in patients on long-term potassium citrate and thiazide therapy.

METHODS

Data were collected on 95 patients who had been on combination therapy for at least 4 months from the stone clinics of the University of Texas Southwestern Medical Center, Duke University Medical Center, and Ochsner Clinic.

RESULTS

Mean serum potassium concentration remained within normal limits without a significant decrease during combined therapy. Serum chloride was significantly lower from pretreatment but by only 1 mEq/L and remained within normal limits throughout treatment. There was a small increase in serum bicarbonate concentration compared to the baseline level of less than 1 mEq/L at 8 to 12 and 18 to 24 months, but not at other treatment periods.

CONCLUSION

Co-administration of potassium citrate did not induce hypokalemia or hypochloremic metabolic alkalosis in our thiazide-treated patient population.

Metabolic alkalosis in the critically ill

Metabolic alkalosis is the commonest form of acid-base disorder seen in critically ill patients. Although the effects of acidosis have long been known, those of severe metabolic alkalosis are only slowly being recognized. Metabolic alkalosis is itself associated with an increased mortality and a knowledge of the causative factors and treatment options is important. In one study, around 50% of general surgical patients developed postoperative metabolic alkalosis, whereas other acid-base disturbances were uncommon. Metabolic alkalosis results from an accumulation of alkali or a loss of acid. Clinical signs are nonspecific but dehydration may be prominent because of a contraction of the extracellular fluid volume due to loss of chloride. Metabolic alkalosis leads to hypoventilation in patients both with and without lung disease, although in the latter, the effect is relatively transient. In patients with chronic obstructive lung disease, however, the development of metabolic alkalosis leads to prolonged hypoventilation and the establishment of a mixed acid-base disorder that may cause difficulty in weaning in the ventilated patient. This is an often forgotten cause of prolonged stay in the intensive care unit with consequent cost and morbidity implications.

Congenital chloride diarrhea: A single center experience with ten patients

Congenital chloride diarrhea (CCD) is a rare autosomal recessive disorder characterized by life-long watery diarrhea with a high fecal chloride concentration. We report the clinical and laboratory data in 20 Saudi infants with CCD admitted to our center between January 1986 and December 1991. In addition to diarrhea, there was a history of maternal polyhydramnios, low birth weights, abdominal distention and failure to thrive. The mean serum and stool chloride concentrations were 71 and 146 mmol/L respectively. Diagnosis was frequently delayed in spite of the early symptoms and the unique association of diarrhea with hypochloremic alkalosis. Treatment with NaCl and KCI solutions in amounts titrated to correct their electrolyte depletion and metabolic alkalosis resulted in marked clinical improvement and growth catch-up. Congenital chloride diarrhea should be suspected in patients with watery stools starting in teh neonatal period or early infancy. The diagnosis is confirmed by the presence of a high fecal chloride concentration and the concomitant hypochloremic alkalosis.

Sodium chloride deficiency in cystic fibrosis patients

Sodium chloride deficiency (SCD) was observed within the 1st year of life in 12 of 46 cystic fibrosis (CF) patients between July 1989 and September 1992. All patients showed sweating, loss of appetite, fever, vomiting, irritation, dehydration, weakness, and cyanosis during an attack. Mean plasma sodium, potassium and chloride levels were 122.9 (range 106-135), 2.5 (range 1.6-3.5), and 73.3 (range 60-90) mEq/l respectively. Alkalosis and elevated plasma renin activity were detected in all patients. Of the patients, 50% showed microscopic haematuria, and hypercalciuria was detected in two out of four patients. Low urinary sodium and high urinary potassium were observed in the four examined patients. Increased creatinine, BUN and uric acid values returned to normal with treatment. All the patients were treated initially with intravenous fluids and electrolyte solutions. All patients were less than 7 months of age during the first attack, five received only breast milk and the others breast milk with formula milk. Their oral salt supplement was 2-4 mEq/kg per day, which is recommended for CF patients, but could be deficient in excessively sweating infants. The genotype of these patients might be cause of high salt losses. F508 is the most common mutation with the frequency of 38% in our CF patients with SCD, but the frequency of unknown mutations is high (54%).

Application of multivariate autoregressive modelling for analysing chloride/potassium/bicarbonate relationship in the body

The authors repeatedly analysed course data of acid-base disturbances accompanying hypochloraemia and/or hypokalaemia by means of multivariate autoregressive modelling. It was found that the regulatory relationship between chloride and bicarbonate is inverse between the following two hypochloraemic hyperbicarbonataemic states: the one induced by chloride depletion and the other induced by CO2 retention. Also, the study revealed an independent role of potassium deficiency in the development of metabolic alkalosis, especially in cases with mineralocorticoid-induced alkalosis. The present approach enabled the authors to solve a long-standing problem, i.e. to differentiate between the roles of chloride and potassium in the development of metabolic alkalosis.

Potassium and anaesthesia

Potassium is the principle intracellular ion, and its concentration and gradients greatly influence the electrical activity of excitable membranes. Because anaesthesia is so intimately involved with electrically active cells, potassium concentrations in surgical patients have received considerable attention in diagnostic and therapeutic applications. With the ongoing evolution in the indications for potassium, it is important to review the role of potassium in cellular activity, in storage and regulation, in diseases that alter potassium homeostasis, and in the therapeutic implications of perioperative alterations of potassium concentration. A rational approach to abnormal potassium values and the use of potassium in the operating room is sought, based on a physiological understanding of risks and benefits.

Gastric conduit urinary diversion in normal dogs. Part II, Hypochloremic metabolic alkalosis

Gastric conduit urinary diversion was performed in 10 dogs after complete cystectomy. Four dogs were euthanatized on day 30 because of hypochloremic metabolic alkalosis and renal failure. Hematologic and biochemical changes in six dogs evaluated for 120 days were compatible with hypochloremic metabolic alkalosis. The continuous loss of hydrochloric acid from the gastric conduit resulted in significant increases in arterial blood pH, PaCO2, anion gap, TCO2, and the concentration of HCO3-. There were significant decreases in PaO2 and the serum concentrations of chloride and potassium. Deterioration of renal function resulted in all dogs. It was concluded that hypochloremic metabolic alkalosis makes gastric conduit urinary diversion unsatisfactory for clinical use in dogs.

In vitro and in vivo assessment of the bioavailability of potassium from a potassium tartrate tablet

The bioavailability of potassium from orally administered potassium tartrate was evaluated in 20 normal subjects under metabolic balance conditions. Subjects were given 34 mmol potassium (5 tablets of Cal-K) as a divided dose on each of 2 consecutive days. Urinary excretion of potassium, as determined from 24-h urinary collections on the 3 days preceding dosage totalled 192.6 +/- 50.9 mmol (mean +/- S.D., n = 20). It increased significantly (p less than 0.05) to 258.7 +/- 54.2 mmol for the 2 days of dosage and the following day. The difference of 66.1 mmol representing absorbed potassium was close to the 68 mmol potassium given and indicated a bioavailability of potassium in excess of 97 per cent; after correction for creatinine excretion, potassium recovery rose to 99.9 per cent. The dissolution characteristics of the Cal-K tablets were also determined. After dissolution in simulated gastric juice (pH 1.2), 84.4 +/- 10.6 per cent (mean +/- S.D., 6 experiments) was dissolved; after adjustment to pH 7.3, dissolved potassium increased to 91.3 +/- 8.5 per cent. No precipitation or residue formed as a result of the pH change. Both sets of results indicate that potassium from these potassium tartrate tablets is in a highly bioavailable form.

Cystic fibrosis presenting with recurrent vomiting and metabolic alkalosis

Between January 1980 and December 1987, ten Saudi Arabian children at Saudi Arabian Oil Co. (Saudi Aramco) health care facilities in the Eastern Province of Saudi Arabia had cystic fibrosis (CF). The incidence of CF in Saudi Arab children less than or equal to 14 years was 1 in 4243. Five of the ten children had hypoelectrolytaemia and metabolic alkalosis on initial presentation. Two of the five had recurrent vomiting, hypoelectrolytaemia and metabolic alkalosis alone and initially no chest symptoms. Early exclusion of CF should be part of the workup in any child, especially in an infant with hypoelectrolytaemia and metabolic alkalosis.

Drug-induced metabolic disorders and parenteral nutrition in the intensive care unit: a pharmaceutical and metabolic perspective

Since its inception, the field of parenteral nutrition has continued to evolve requiring the expertise of several health care disciplines. This feature has made nutrition support unique among clinical subspecialties. As a member of this team, the pharmacist plays a critical role in the provision of sterile admixtures, compatible nutritional formulations, and cost-effective, therapeutically equivalent strategies. The pharmacist has become more involved in the clinical care of the patient, with particular emphasis on the development of drug-induced metabolic disorders. The multitude of drugs prescribed to hospitalized patients increases the potential for serious metabolic disturbances. This is especially true in the critical care setting where sudden changes in metabolism (e.g., acid-base homeostasis, fluid and electrolyte balance) may result in profoundly negative effects. The critical care setting also represents the most sensitive period of hospitalization where even subtle changes in metabolic homeostasis may assume major clinical significance. Early recognition of offending agents and the institution of appropriate intervention may avert serious iatrogenic diseases. The nutrition support team is in a unique position to address many such disorders through selective manipulation of the various components in the parenteral nutrient admixture. The ability of the pharmacist to recognize the development of drug-induced metabolic disorders lends further support for clinical pharmacy in nutrition support services.

Effects of chloride and extracellular fluid volume on bicarbonate reabsorption along the nephron in metabolic alkalosis in the rat. Reassessment of the classical hypothesis of the pathogenesis of metabolic alkalosis

Volume expansion has been considered essential for the correction of chloride-depletion metabolic alkalosis (CDA). To examine the predictions of this hypothesis, rats dialyzed against 0.15 M NaHCO3 to produce CDA and controls, CON, dialyzed against Ringer-HCO3 were infused with either 6% albumin (VE) or 80 mM non-sodium chloride salts (CC) added to 5% dextrose (DX) and studied by micropuncture. CDA was maintained in rats infused with DX. VE expanded plasma volume (25%), maintained glomerular filtration rate (GFR), but did not correct CDA despite increased fractional delivery of total CO2 (tCO2) out of the proximal tubule (36 +/- 2%) as compared with VE/CON (24 +/- 4%; P less than 0.05). In contrast, CC corrected CDA despite volume contraction (-16%) and lower GFR than CC/CON; proximal tCO2 delivery in CC/CDA (29 +/- 4%) did not differ from VE/CDA. CC was associated with an increment in tCO2 excretion. The data strongly suggest that maintenance and correction of CDA are primarily dependent upon total body chloride and its influences on intrarenal mechanisms and not on the demands of sodium or fluid homeostasis.

Evaluation of the patient with congestive heart failure and ventricular arrhythmias

Although vasodilators and new inotropic agents have been shown to improve ventricular function and reduce symptoms, their effect on mortality is uncertain. In view of our failure to reduce mortality in patients with congestive heart failure (CHF), the identification and amelioration of potentially reversible factors that might alter survival are crucial before initiating therapy. The first step is to establish the diagnosis of CHF and the presence or absence of dilated congestive cardiomyopathy. The extent of myocardial dysfunction, both right and left, must also be evaluated. In post-myocardial infarction patients, left ventricular ejection fraction is an important indicator of prognosis during the first 1 to 2 years. However, in patients with chronic CHF and dilated cardiomyopathy, right ventricular ejection fraction may be a more effective predictor of survival. The presence, frequency and complexity of ventricular arrhythmias must be determined, because these arrhythmias may independently increase the risk of sudden cardiac death in patients with ischemic cardiomyopathy. Their role in patients with idiopathic cardiomyopathy is less certain. In addition, myocardial ischemia, left ventricular dyskinesis or aneurysm, occult myocarditis and neurothrombosis formation must be ruled out. Detection and correction of serum electrolyte and neurohumeral abnormalities are essential. Our failure to reduce mortality in patients with CHF may not entirely lie in the lack of effective therapeutic agents but rather in our failure to apply properly the diagnostic and therapeutic approaches now available.

Electrocardiographic finding simulating acute myocardial infarction in a compound metabolic aberration

A patient with hypokalemic metabolic alkalosis, hypophosphatemia, and hypomagnesemia/hypocalcemia is described. Electrocardiography demonstrated the pattern of acute anterior myocardial infarction. Further evaluation revealed that the patient had not actually had the acute myocardial infarction and that the electrocardiographic change was a mere simulation. The possible role of hypomagnesemia in the pathogenesis of the electrocardiographic change and the interrelation between the metabolic disturbances noted are discussed.

Segmental chloride and fluid handling during correction of chloride-depletion alkalosis without volume expansion in the rat

To determine whether chloride-depletion metabolic alkalosis (CDA) can be corrected by provision of chloride without volume expansion or intranephronal redistribution of fluid reabsorption, CDA was produced in Sprague-Dawley rats by peritoneal dialysis against 0.15 M NaHCO3; controls (CON) were dialyzed against Ringer's bicarbonate. Animals were infused with isotonic solutions containing the same Cl and total CO2 (tCO2) concentrations as in postdialysis plasma at rates shown to be associated with slight but stable volume contraction. During the subsequent 6 h, serum Cl and tCO2 concentrations remained stable and normal in CON and corrected towards normal in CDA; urinary chloride excretion was less and bicarbonate excretion greater than those in CON during this period. Micropuncture and microinjection studies were performed in the 3rd h after dialysis. Plasma volumes determined by 125I-albumin were not different. Inulin clearance and fractional chloride excretion were lower (P less than 0.05) in CDA. Superficial nephron glomerular filtration rate determined from distal puncture sites was lower (P less than 0.02) in CDA (27.9 +/- 2.3 nl/min) compared with that in CON (37.9 +/- 2.6). Fractional fluid and chloride reabsorption in the proximal convoluted tubule and within the loop segment did not differ. Fractional chloride delivery to the early distal convolution did not differ but that out of this segment was less (P less than 0.01) in group CDA. Urinary recovery of 36Cl injected into the collecting duct segment was lower (P less than 0.01) in CDA (CON 74 +/- 3; CDA 34 +/- 4%). These data show that CDA can be corrected by the provision of chloride without volume expansion or alterations in the intranephronal distribution of fluid reabsorption. Enhanced chloride reabsorption in the collecting duct segment, and possibly in the distal convoluted tubule, contributes importantly to this correction.

Urinary sodium and chloride during renal salt retention

One hundred ten episodes of renal salt retention (urinary sodium and/or chloride less than 10 mEq/L) were studied retrospectively to determine the significance of discordance of urinary sodium from chloride. In 16 episodes the urinary sodium exceeded chloride by at least 15 mEq/L. This disparity was associated with the necessity for urinary excretion of substantial quantities of poorly reabsorbed anions (penicillin, ketones, or diatrizoate), a rapidly falling serum bicarbonate level (due to resolving metabolic or developing respiratory alkalosis), or substantial renal insufficiency (serum creatinine greater than 3 mg/dL). In 14 of 110 episodes, urinary chloride exceeded urinary sodium by at least 15 mEq/L. These patients were more often oliguric and had a higher mean serum chloride than patients without this dissociation. In patients with oliguria, hyponatremia, or metabolic alkalosis, measurement of urinary sodium or chloride alone will, in a substantial number of cases, fail to detect renal salt retention. When evidence is sought for renal salt retention, both urinary sodium and chloride should be determined.

New method for administration of hydrochloric acid in metabolic alkalosis

In a new method for peripheral intravenous infusion of hydrochloric acid the HCl is buffered in an aminoacid solution and infused with a fat emulsion. The aminoacids and the fat emulsions are stable in the presence of HCl, and the transfusion set is resistant to the chemical actin of 0.15 mol/l HCl. Two case-reports show that HCl can be administered safely through a peripheral vein.

Cardiovascular performance and oxyhemoglobin dissociation after acetazolamide in metabolic alkalosis

In patients with metabolic alkalosis, compensatory alveolar hypoventilation may induce hypercapnia and hypoxemia. In edematous or normally-hydrated patients without electrolyte deficiencies, acetazolamide--a carbonic anhydrase inhibitor--has been advocated to correct the primary acid-base disturbance, thereby preventing hypoxemia. The hemodynamic consequences and the effect on oxyhemoglobin dissociation of acetazolamide, were studied. Twelve critically ill patients with metabolic alkalosis were given 15 mg/kg body wt. acetazolamide intravenously. Cardiovascular performance was completely unchanged. The P50 was 26.6 mm Hg at the beginning and the end of the study, indicating that hemoglobin-oxygen affinity is unaffected by acetazolamide. In six patients, investigated after open-heart surgery, the arterial oxygen tension increased by 10-45%. This was probably related to the combined effects of slight reductions in total body oxygen consumption or shunting of venous blood through the lungs. Eight of the 12 patients were on controlled ventilation. After acetazolamide there was a mean increase in mixed venous carbon dioxide tension (PvCO2) of 4.5 mm Hg, with no increase in arterial carbon dioxide tension (PaCO2), indicating only a limited interference with carbon dioxide uptake and release of the carbonic anhydrase inhibition. No other adverse reactions were observed.

Lysine hydrochloride for the control of metabolic alkalosis: a clinical report

Many physiopathological states can produce metabolic alkalosis that must be promptly corrected as soon as it is dangerous. In our study we report the effectiveness of lysine hydrochloride to correct this condition in patients. This drug lowers the pH, reduces the bicarbonate stores, and leads to normal blood gases.

Diuretics stimulate H+ secretion in turtle urinary bladder

The effect of various diuretics on H+ secretion was studied in the isolated short-circuited urinary bladder of the turtle. Mucosal (urinary) chlorothiazide stimulated H+ secretion promptly, from 1.33 +/- 0.24 to 3.03 +/- 0.25 mueq/h (P less than 0.001). The effect was rapidly reversible upon washout of the drug, H+ returning to control levels, 1.37 +/- 0.26 mueq/h (P less than 0.001). Similar effects were observed with mucosal hydrochlorothiazide and mucosal ethacrynic acid/cysteine. Stimulation of H+ secretion occurred in the presence or the absence of exogenous CO2, in the presence or absence of mucosal Na+ and during inhibition of Na+ transport by ouabain. There was no stimulation of H+ secretion by uncomplexed ethacrynic acid or by mucosal furosemide. The nondiuretic sulfonamide, sulfasoxizole, and the nonsulfonamide buffer, borate, had no effect on H+ SECRETION. These observations indicate that the stimulatory effect of diuretics on H+ secretion is not related to active sodium transport, transepithelial electrical potential, or the buffering capacity of the drugs. Since the transepithelial pH gradient at which active H+ secretion was abolished was identical for chlorothiazide-treated tissues (2.68 pH U) as for control tissues (2.65 pH U, NS), the data suggest that the protonmotive force of the H+ pump was unaffected by the diuretic. This observation, plus the rapid onset and reversibility of the drugs, is consistent with an effect on the mucosal membrane to increase H+ conductance (K). The findings raise the possibility that direct enhancement of renal H+ secretion may play a role in the metabolic alkalosis induced by some diuretics.

Effect of Sar1-ala8-angiotensin II on blood pressure and renin in Bartter's syndrome, before and after treatment with prostaglandin synthetase inhibitors

Three patients suffering from Bartter's syndrome were studied before and after 5 days of treatment with the prostaglandin synthetase inhibitors, aspirin and indomethacin. Saralasin was given by intravenous infusion in increasing doses from 0.6 to 42 micrograms/min.kg/BW. During saralasin infusion a blood pressure reduction was observed in all patients. Aspirin treatment did not affect this response and nor did it affect other manifestations of the syndrome. Indomethacin treatment changed the blood pressure response to saralasin in such a way that the blood pressure was increased in one patient and was unchanged in the other. Indomethacin also tended to normalize other features of Bartter's syndrome, such as the hyperreninaemia and angiotensin unresponsiveness, but did not affect the hypokalaemia. The saralsin effect on blood pressure is thus evidently inversely related to the prevailing activity of the renin-angiotensin system in this condition also, and the patients obviously depended on the renin-angiotensin system to maintain their blood pressure. Our findings, together with data in the literature, indicate that angiotensin unresponsiveness of the vascular bed is not a primary feature in Bartter's syndrome. Chloride loss is currently thought to be the basic abnormality and this may link the Bartter's syndrome with other diseased states characterized by chloride loss, such as the syndrome of habitual vomiting and chronic treatment with loop diuretics.

The use of dilute hydrochloric acid and cimetidine to reverse severe metabolic alkalosis

Two cases of severe metabolic alkalosis associated with gastric hypersecretion were successfully treated with dilute hydrochloric acid and a histamine H2-receptor antagonist given by intravenous infusion. This combined therapy with electrolyte replacement and suppression of gastric secretion is valuable in the control of this serious metabolic abnormality when conventional treatment is unsuccessful or contraindicated.

Hydrogen ion metabolism

The renal and respiratory systems regulate acid base homeostasis by modifying the bicarbonate buffer pair HCO3- and CO2; other buffer systems adjust to alterations in this pair. The pH change following addition of metabolic acid, or base, is modified initially by the body's buffers. Subsequent respiratory compensation, by retention or excretion of CO2, modifies further this change before renal corrective responses finally occur. A primary respiratory acid base change is modified initially by cellular buffers, with renal compensatory mechanisms adjusting slowly to this change. However correction of the respiratory pH disorder only occurs with correction of the primary disease process. The body's capacity, therefore, to adjust to a matabolic acid base defect, appears greater than that observed with a primary respiratory pH abnormality. Treatment in all acid base disorders focuses initially upon the primary diseases process; thereafter therapeutic manipulation of the HCO3-, CO2 buffer pair, to aid the body's compensatory processes, can be considered.

The efficacy and safety of furosemide and a combination of spironolactone and hydrochlorothiazide in congestive heart failure

The therapeutic and biochemical effects of two commonly employed diuretic preparations were compared in a double-blind fashion in 32 patients with congestive heart failure. At the doses employed, furosemide and a fixed combination of spironolactone and hydrochlothiazide maintained control of the clinical manifestations of congestive heart failure to about the same degree. However, significant biochemical changes in the renin-aldosterone system were found in patients receiving the spironolactone/thiazide combination therapy. A significant increase in plasma renin activity and a significantly greater increase in aldosterone excretion were found in the spironolactone/thiazide group compared to the furosemide group. No significant differences were observed in serum potassium levels or 24-hour potassium excretion rates in patients treated with the two diuretic preparations.

Relationship of renal ammonia production and potassium homeostasis

Renal ammonia production appears to be intimately related to potassium homeostasis, and the two may comprise the components of a closed loop regulatory system. Studies with both intact organisms and in vitro systems indicate that potassium depletion stimulates and chronic potassium-loading suppresses renal ammonia production. An increase in ammoniagenesis has been shown to decrease potassium excretion. These observations suggest that changes in potassium modulate ammonia production, which in turn maintains hydrogen ion homeostasis and influences potassium excretion. Potassium depletion increases rat renal cortical ammonia production by altering metabolism in fashion identical to metabolic acidosis, but there is no convincing evidence that both processes are mediated by similar changes in either cellular hydrogen ion or potassium concentration. By contrast, potassium-loading, which depresses ammonia production, appears to affect primarily the outer medulla, a region that is not influenced by potassium depletion. Thus, potassium-loading apparently affects different portions of the renal tubule than depletion does, but the specific mechanism and physiologic significance of the different sites of action is unknown.