Prenatally programmed hypertension: role of maternal diabetes

Epidemiological and experimental studies have led to the hypothesis of the fetal origin of adult diseases, suggesting that some adult diseases might be determined before birth by altered fetal development. Maternal diabetes subjects the fetus to an adverse environment that has been demonstrated to result in metabolic, cardiovascular and renal impairment in the offspring. The growing amount of obesity in young females in developed and some developing countries should contribute to increasing the incidence of diabetes among pregnant women. In this review, we discuss how renal and extrarenal mechanisms participate in the genesis of hypertension induced by a diabetic status during fetal development.

Dysregulation of ENaC in Animal Models of Nephrotic Syndrome and Liver Cirrhosis

Nephrotic syndrome and liver cirrhosis are common clinical manifestations, and are associated with avid sodium retention leading to the development of edema and ascites. However, the mechanism for the sodium retention is still incompletely understood and the molecular basis remains undefined. We examined the changes of sodium (co)transporters and epithelial sodium channels (ENaCs) in the kidneys of experimental nephrotic syndrome and liver cirrhosis. The results demonstrated that puromycin- or HgCl2?induced nephrotic syndrome was associated with 1) sodium retention, decreased urinary sodium excretion, development of ascites, and increased plasma aldosterone level; 2) increased apical targeting of ENaC subunits in connecting tubule and collecting duct segments; and 3) decreased protein abundance of type 2 11beta-hydroxysteroid dehydrogenase (11betaHSD2). Experimental liver cirrhosis was induced in rats by CCl4 treatment or common bile duct ligation. An increased apical targeting of alpha-, beta-, and gamma-ENaC subunits in connecting tubule, and cortical and medullary collecting duct segments in sodium retaining phase of liver cirhosis but not in escape phase of sodium retention. Immunolabeling intensity of 11betaHSD2 in the connecting tubule and cortical collecting duct was significantly reduced in sodium retaining phase of liver cirrhosis, and this was confirmed by immunoblotting. These observations therefore strongly support the view that the renal sodium retention associated with nephrotic syndrome and liver cirrhosis is caused by increased sodium reabsorption in the aldosterone sensitive distal nephron including the connecting tubule and collecting duct, and increased apical targeting of ENaC subunits plays a role in the development of sodium retention in nephrotic syndrome and liver cirrhosis.

Contributory Roles of Distal Renal Sodium Transporters in NSAID-induced Sodium Retention / 대한신장학회잡지

BACKGROUND: Sodium retention occurs in some patients taking NSAIDs (nonsteroidal anti-inflammatory drugs). Although the renal effects of NSAIDs are predominantly mediated through the inhibition of prostaglandins synthesized by cyclooxygenase-2 (COX-2), the mechanisms of sodium retention are not clear at the sodium transporter levels in the kidney. Previous studies have shown that compensatory upregulation of COX-2 is induced in renal medulla by high salt intake and that NSAID-induced sodium retention may be transitory. METHODS: To investigate whether renal sodium transporter abundances are altered by NSAID administration and whether renal sodium transporter abundances are affected by high salt intake or chronic NSAID administration, we performed an acute study treated with a single injection of diclofenac and another chronic study treated with 7 days' administration of DFU, a selective COX-2 inhibitor, using semiquantitative immunobotting from rat kidneys. Male Sprague-Dawley rats were divided into three groups in each study: controls, NSAID treatment, and high-salt intake plus NSAID treatment. The control diet contained sodium 1 mmol/200 g BW/day, and the high-salt diet 10 mmol/200 g BW/day. RESULTS: The acute study using diclofenac (100 mg/kg BW) increased the abundances of NKCC2 (by 73%) and ENaC-alpha (by 60%) in cortex and of NKCC2 (by 165%) and ENaC-alpha (by 91%) in outer medulla, in association with a significant decrease in urinary sodium excretion. The increased ENaC-alpha abundance was reversed by addition of high salt intake in both cortex and outer medulla. The chronic study using DFU (40 mg/kg/d for 7 days) showed no significant changes in distal renal sodium transporters except a decreased abundance of Na-K- ATPase alpha1-subunit (by 24%) in outer medulla. The addition of high salt intake decreased the abundances of ENaC-alpha (by 35%) and ENaC-beta (by 47 %) in outer medulla. CONCLUSION: The abundances of thick ascending limb NKCC2 and collecting duct ENaC are altered in response to NSAID administration. It is suggested that NKCC2 & ENaC are contributory to NSAID- induced sodium retention and also have a compensatory role in high salt intake and chronic NSAID administration.