Severe metabolic alkalosis due to diuretic treatment in a patient with distal renal tubular acidosis: a rare association

N-Heterocyclic Carbene-Catalyzed Facile Synthesis of Phthalidyl Sulfonohydrazones: Density Functional Theory Mechanistic Insights and Docking Interactions

N-heterocyclic carbene catalysis reaction protocol is disclosed for the synthesis of phthalidyl sulfonohydrazones. A broad range of N-tosyl hydrazones react effectively with phthalaldehyde derivatives under open-air conditions, enabling the formation of a new C-N bond via an oxidative path. The reaction proceeds under mild reaction conditions with broad substrate scopes, wide functional group tolerance, and good to excellent yields. The mechanistic pathway is studied successfully using control experiments, competitive reactions, ESI-MS spectral analyses of the reaction mixture, and computational study by density functional theory. The potential use of one of the phthalidyl sulfonohydrazone derivatives as the inhibitor of β-ketoacyl acyl carrier protein synthase I of Escherichia coli is investigated using molecular docking.

The B1 H + -ATPase ( Atp6v1b1 ) Subunit in Non-Type A Intercalated Cells is Required for Driving Pendrin Activity and the Renal Defense Against Alkalosis

SIGNIFICANCE STATEMENT

In the kidney, the B1 H + -ATPase subunit is mostly expressed in intercalated cells (IC). Its importance in acid-secreting type A ICs is evident in patients with inborn distal renal tubular acidosis and ATP6V1B1 mutations. However, the protein is also highly expressed in alkali-secreting non-type A ICs where its function is incompletely understood. We demonstrate in Atp6v1b1 knock out mice that the B1 subunit is critical for the renal response to defend against alkalosis during an alkali load or chronic furosemide treatment. These findings highlight the importance of non-type A ICs in maintaining acid-base balance in response to metabolic challenges or commonly used diuretics.

BACKGROUND

Non-type A ICs in the collecting duct system express the luminal Cl - /HCO 3- exchanger pendrin and apical and/or basolateral H + -ATPases containing the B1 subunit isoform. Non-type A ICs excrete bicarbonate during metabolic alkalosis. Mutations in the B1 subunit (ATP6V1B1) cause distal renal tubular acidosis due to its role in acid secretory type A ICs. The function of B1 in non-type A ICs has remained elusive.

METHODS

We examined the responses of Atp6v1b1-/- and Atp6v1b1+/+ mice to an alkali load and to chronic treatment with furosemide.

RESULTS

An alkali load or 1 week of furosemide resulted in a more pronounced hypokalemic alkalosis in male ATP6v1b1-/- versus Atp6v1b1+/+ mice that could not be compensated by respiration. Total pendrin expression and activity in non-type A ICs of ex vivo microperfused cortical collecting ducts were reduced, and β2 -adrenergic stimulation of pendrin activity was blunted in ATP6v1b1-/- mice. Basolateral H + -ATPase activity was strongly reduced, although the basolateral expression of the B2 isoform was increased. Ligation assays for H + -ATPase subunits indicated impaired assembly of V 0 and V 1 H + -ATPase domains. During chronic furosemide treatment, ATP6v1b1-/- mice also showed polyuria and hyperchloremia versus Atp6v1b1+/+ . The expression of pendrin, the water channel AQP2, and subunits of the epithelial sodium channel ENaC were reduced.

CONCLUSIONS

Our data demonstrate a critical role of H + -ATPases in non-type A ICs function protecting against alkalosis and reveal a hitherto unrecognized need of basolateral B1 isoform for a proper H + -ATPase complexes assembly and ability to be stimulated.

Renal calcification in children with renal tubular acidosis: What a paediatrician ‎should ‎know‎

Renal tubular acidosis (RTA) can lead to renal calcification in children, which can cause various complications and impair renal function. This review provides pediatricians with a comprehensive understanding of the relationship between RTA and renal calcification, highlighting essential aspects for clinical management. The article analyzed relevant studies to explore the prevalence, risk factors, underlying mechanisms, and clinical implications of renal calcification in children with RTA. Results show that distal RTA (type 1) is particularly associated with nephrocalcinosis, which presents a higher risk of renal calcification. However, there are limitations to the existing literature, including a small number of studies, heterogeneity in methodologies, and potential publication bias. Longitudinal data and control groups are also lacking, which limits our understanding of long-term outcomes and optimal management strategies for children with RTA and renal calcification. Pediatricians play a crucial role in the early diagnosis and management of RTA to mitigate the risk of renal calcification and associated complications. In addition, alkaline therapy remains a cornerstone in the treatment of RTA, aimed at correcting the acid-base imbalance and reducing the formation of kidney stones. Therefore, early diagnosis and appropriate therapeutic interventions are paramount in preventing and managing renal calcification to preserve renal function and improve long-term outcomes for affected children. Further research with larger sample sizes and rigorous methodologies is needed to optimize the clinical approach to renal calcification in the context of RTA in the pediatric population.