Renal sodium metabolism, a major determinant of blood pressure, is regulated with great precision by a variety of endocrine, autocrine, and neuronal factors. Although these factors are known to regulate sodium metabolism by affecting the rate of tubular sodium reabsorption, the molecular mechanisms by which they act are poorly understood. Na+,K(+)-ATPase plays a pivotal role for sodium reabsorption in all tubular segments. The activity of this enzyme can be dynamically regulated by phosphorylation and dephosphorylation. Here we summarize both old and new evidence that several major substances believed to be involved in the regulation of sodium metabolism and blood pressure, i.e., the antidiuretic agents angiotensin II and norepinephrine, and the diuretic agents dopamine and atrial natriuretic peptide (ANP), may achieve their effects through a common pathway that involves reversible activation/deactivation of renal tubular Na+,K(+)-ATPase. Regulation of Na+,K(+)-ATPase activity was studied using a preparation of single proximal tubule (PT) segments, dissected from rat kidneys. Na+,K(+)-ATPase activity was stimulated by angiotensin II and the alpha-adrenergic agonist, oxymetazoline, at physiological, nonsaturating Na+ concentrations. These stimulatory effects were blocked by dopamine and ANP as well as by their respective second messengers, cAMP and cGMP. They were also blocked by the specific protein phosphatase 2B inhibitor FK506. These results indicate that regulation of sodium excretion by norepinephrine, angiotensin II, dopamine, and ANP can be accounted for by a bidirectionally regulated intracellular protein phosphorylation cascade that modulates the activity of renal tubular Na+,K(+)-ATPase.

Although the diagnosis of Gitelman syndrome (GS) and Bartter syndrome (BS) is now feasible by genetic analysis, implementation of genetic testing for these disorders is still hampered by several difficulties, including large gene dimensions, lack of hot-spot mutations, heavy workup time, and costs. This study evaluated in a cohort of patients with genetically proven GS or BS diagnostic sensibility and specificity of a diuretic test with oral hydrochlorothiazide (HCT test). Forty-one patients with GS (22 adults, aged 25 to 57; 19 children-adolescents, aged 7 to 17) and seven patients with BS (five type I, two type III) were studied; three patients with "pseudo-BS" from surreptitious diuretic intake (two patients) or vomiting (one patient) were also included. HCT test consisted of the administration of 50 mg of HCT orally (1 mg/kg in children-adolescents) and measurement of the maximal diuretic-induced increase over basal in the subsequent 3 h of chloride fractional clearance. All but three patients with GS but no patients with BS and pseudo-BS showed blunted (<2.3%) response to HCT; patients with BS and the two patients with pseudo-BS from diuretic intake had increased response to HCT. No overlap existed between patients with GS and both patients with BS and pseudo-BS. The response to HCT test is blunted in patients with GS but not in patients with BS or nongenetic hypokalemia. In patients with the highly selected phenotype of normotensive hypokalemic alkalosis, abnormal HCT test allows prediction with a very high sensitivity and specificity of the Gitelman genotype and may avoid genotyping. M utations of several genes that are involved in Na/ fluid reabsorption along the distal nephron are the cause of tubular disorders that are characterized by chronic hypokalemic alkalosis and normotensive, hyperreninemic hyperaldosteronism, including Gitelman syndrome (GS; OMIM 263800) and Bartter syndrome (BS) types I to V (1-3) (OMIM 241200, 601678, 607364, 602522, and 601199). Chronic normotensive hypokalemia and alkalosis may also be acquired as a result of known or unknown diuretic use, anorexia/bulimia, and laxative abuse (4 -6). Clinical history and biochemical workup may not allow definite diagnosis, especially concerning the different types of tubular disorders. Genetic diagnosis is now feasible for all known genes that are responsible for GS and BS, but in everyday practice, it remains not easily available for the clinician and, for the geneticist, costly, cumbersome, and time-consuming as a result of the great dimension of most genes, lack of hot-spot mutations, and the very large number of mutations described. Furthermore, in approximately 40% of patients with GS, only a single heterozygous mutation in the SLC12A3 gene is detected (7), so further examination of a second gene is usually necessary.Tests with diuretics have been used in the past to diagnose tubular disorders (8 -12) and nontubular conditions (5); however, genetic confirmation of the supposed diagnosis was rarely, if ever, available. We present the di...

The SLC12A3 gene encodes the thiazide-sensitive Na-Cl co-transporter (NCCT) expressed in the apical membrane of the distal convoluted tubule of the kidney. Inactivating mutations of this gene are responsible for Gitelman syndrome (GS), a disorder inherited as an autosomal recessive trait. We searched for SLC12A3 gene mutations in 21 Italian patients with the clinical and biochemical features of GS (hypokalemia, hypomagnesemia, metabolic alkalosis, hypocalciuria, and the absence of nephrocalcinosis). All coding regions with their intron-exon boundaries were analyzed using PCR and SSCP techniques followed by sequencing analysis. We identified 21 different mutations evenly distributed throughout the gene without any mutation hot-spot. Fifteen are novel variants, including 12 missense mutations, one deletion, one deletion-insertion and one splice site mutation: R158Q, T163M, W172R, G316V, G374V, G463E, A464T, S615W, V677M, R852S, R958G, C985Y, 2114-2120delACCAAGT, 2144-2158delGCCTTCTACTCGGATinsTG, and 531-2A>G.

Cholangiopathies attributable to highly penetrant ABCB4 mutant alleles are identifiable in a substantial proportion of adults that generally have PFH-CLD. In PSC and ICC phenotypes, patients with MDR3 deficiency have early onset of disease.

Diet and inflammatory response are recognized as strictly related, and interest in exploring the potential of edible fats and oils for health and chronic diseases is emerging worldwide. Polyunsaturated fatty acids (PUFAs) present in fish oil (FO), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may be partly converted into oxygenated bioactive lipids with anti-inflammatory and/or pro-resolving activities. Moreover, the co-presence of phenolic compounds and vitamins in edible oils may prevent the development of chronic diseases by their anti-inflammatory, antioxidant, neuroprotective, and immunomodulatory activities. Finally, a high content in mono-unsaturated fatty acids may improve the serum lipid profile and decrease the alterations caused by the oxidized low-density lipoproteins and free radicals. The present review aims to highlight the role of lipids and other bioactive compounds contained in edible oils on oxidative stress and inflammation, focusing on critical and controversial issues that recently emerged, and pointing to the opposing role often played by edible oils components and their oxidized metabolites.

Inactivating mutations in the SLC12A3 gene that encodes the thiazide-sensitive co-transporter causes Gitelman syndrome. The main features of this syndrome include normal or low blood pressure, hypokalemia, metabolic alkalosis, hypomagnesemia, hypocalciuria, and hyperreninemia. These patients are at low risk for preterm birth and do not present with symptoms before school age. As a consequence, the condition is usually diagnosed in late childhood or in adult life. We report on four patients, two pairs of prematurely born twins, in whom hypokalemia was demonstrated early in life. In these children, a tendency towards hypokalemia was first noted during the third week of life. Overt hypokalemia subsequently appeared associated with normal blood pressure, hypochloremia, hyperreninemia, and an inappropriately high fractional excretion of potassium and chloride. Molecular biology studies failed to detect mutations in the SLC12A1, KCNJ1, and CLCNKB genes responsible for the Bartter syndromes type I, II and III, respectively. Compound heterozygous mutations in the SLC12A3 gene were detected in both pairs of twins: a frameshift mutation in exon 10 (c.1196_1202dup7bp), leading to the truncated protein p.Ser402X, and a missense mutation in exon 11, p.Ser475Cys (c.1424C>G) in the first pair; two missense mutations, p.Thr392Ile (c.1175C>T) in exon 9 and p.Ser615Leu in exon 15 (c.1844C>T), in the second pair. In conclusion, the diagnosis of Gitelman syndrome deserves consideration in infants with unexplained hypokalemia.

Depression is one of the most important health problems worldwide. Women are 2.5 times more likely to experience major depression than men. Evidence suggests that some women might experience an increased risk for developing depression during “windows of vulnerability”, i.e., when exposed to intense hormone fluctuations, such as the menopause transition. Indeed, this period is associated with different symptoms, including vasomotor, depressive, and cognitive symptoms, which have all been shown to worsen as women approach menopause. Even though hormonal therapy represents the most effective treatment, side effects have been reported by several studies. Therefore, an increased number of women might prefer the use of alternative medicine for treating menopausal symptoms. N-3 long-chain polyunsaturated fatty acids (n-3 LCPUFAs) are included among these alternative treatments. We here provide a review of studies investigating the effects of n-3 LCPUFAs on hot flashes and depressive and cognitive disorders in menopausal women. The reported results are scattered and heterogeneous. In conclusion, a beneficial role of n-3 LCPUFAs in hot flashes, and depressive and cognitive symptoms related to menopausal transition is still far from conclusive.

Milan hypertensive (MSH) rats develop hypertension around the 3rd-4th week of life and exhibit increased Na-pump activity in adulthood. The present study was performed to evaluate whether or not hypertension is preceded by an increase in Na-K-ATPase activity. Total and ouabain-sensitive ATPase activities were studied in single microdissected medullary thick ascending limb of Henle (mTAL) tubules from MHS, Milan normotensive (MNS) and Sprague-Dawley (SD) rats at 22-24, 26-28 and 45-60 days of age. Data are given as mean +/- SEM. Total and Na-K-ATPase activity exhibited a developmental pattern in MHS, MNS and SD rats. At 22-24 days no difference was seen between MHS and MNS animals. At 26-28 days MHS had a higher total and Na-K-ATPase activity than MNS (3031 + 171 vs 2471 + 178 pmol phosphate/mm tubule per hour, P less than 0.05; 2289 + 205 vs 1653 + 151, n = 10, P less than 0.05). At this age there was still no difference in mean arterial blood pressure (88 + 4 vs 86 + 3 mm Hg, n = 15). Adult MHS rats had higher blood pressure (140 + 9 vs 112 + 8 mm Hg, P less than 0.001) and higher total (3544 + 136 vs 2718 + 215 pmol phosphate/mm tubule per hour, n = 10, P less than 0.01) and Na-K-ATPase activity (2670 + 99 vs 1942 + 217 pmol phosphate/mm tubule per hour, n = 10, P less than 0.05) than adult MNS rats.(ABSTRACT TRUNCATED AT 250 WORDS)