Background: High-NaCl diet is a contributing factor for cardiac hypertrophy. The role of HSP22 as a protective protein during cardiac hypertrophy due to hypernatremia is unclear. Accordingly, this study aimed to establish a cellular hypernatremic H9C2 model and to compare the expression of HSP22 in Ca2+ homeostasis between a high-NaCl and angiotensin II-induced hypertrophic cellular H9C2 model. Methods: Real-time PCR was performed to compare the mRNA expression. Flow cytometry and confocal microscopy were used to analyze the cells. Results: The addition of 30 mM NaCl for 48 h was the most effective condition for the induction of hypertrophic H9C2 cells (termed the in vitro hypernatremic model). Cardiac cellular hypertrophy was induced with 30 mM NaCl and 1 μM angiotensin II for 48 h, without causing abnormal morphological changes or cytotoxicity of the culture conditions. HSP22 contains a similar domain to that found in the consensus sequences of the late embryogenesis abundant protein group 3 from Artemia. The expression of HSP22 gradually decreased in the in vitro hypernatremic model. In contrast to the in vitro hypernatremic model, HSP22 increased after exposure to angiotensin II for 48 h. Intracellular Ca2+ decreased in the angiotensin II model and further decreased in the in vitro hypernatremic model. Impaired intracellular Ca2+ homeostasis was more evident in the in vitro hypernatremic model. Conclusion: The results showed that NaCl significantly decreased HSP22. Decreased HSP22, due to the hypernatremic condition, affected the Ca2+ homeostasis in the H9C2 cells. Therefore, hypernatremia induces cellular hypertrophy via impaired Ca2+ homeostasis. The additional mechanisms of HSP22 need to be explored further.

• Cardiac hypertrophy
• Late embryogenesis abundant protein
• HSP22 protein
• Homeostasis

A 47-year-old female previously diagnosed with ADPKD visited the hospital due to sudden pain in her upper abdomen and back. Esophagogastroduodenoscopy, contrast-enhanced abdominal computed tomography (CT), and CT angiography identified an esophageal artery pseudoaneurysm and hematoma in the esophagus. Urgent angiography and embolization were performed. After the procedure, CT angiography and positron emission tomography were performed due to differences in blood pressure between the arms. The patient was also found to have Takayasu arteritis and subsequently received outpatient follow-up care. The possible mechanisms that cause vascular abnormalities in ADPKD patients include damaged vascular integrity due to abnormal polycystin expression caused by PKD mutations and connective tissue abnormalities. Further research is needed to confirm these mechanisms, and ADPKD patients should be assessed for vascular abnormalities.

• Autosomal dominant polycystic kidney disease (ADPKD)
• Aneurysms
• Takayasu arteritis

Severe eating disorders characterized by repetitive episodes of purging and vomiting can occasionally trigger acute kidney injury. However, interstitial nephritis induced by episodes of repeated vomiting has rarely been reported, and the pathophysiology of this entity remains unknown. A 26- year-old man was admitted to our hospital because of known hypokalemia. His serum electrolyte profile showed: sodium 133 mEq/L, potassium 2.6 mEq/L, chloride 72 mEq/L, total carbon dioxide 50 mEq/L, blood urea nitrogen/ creatinine ratio (BUN/Cr) 21.9/1.98 mg/dL, and magnesium 2.0 mg/dL. Arterial blood gas analysis showed: pH 7.557, partial pressure of carbon dioxide 65.8 mmHg, and bicarbonate 58.5 mEq/L. His urinary potassium concentration was 73.2 mEq/L, and Cr was 111 mg/dL. Renal biopsy revealed acute tubular necrosis and tubulointerstitial nephritis with a few shrunken glomeruli. Repeated psychogenic vomiting may precipitate acute kidney injury and interstitial nephritis secondary to volume depletion and hypokalemia. Serum electrolyte levels and renal function should be carefully monitored in patients diagnosed with eating disorders to prevent tubular ischemia and interstitial nephritis.

• Interstitial nephritis
• anorexia
• hypokalemia
• tubular necrosis