Glucocorticoid receptor activation stimulates the sodium-chloride cotransporter and influences the diurnal rhythm of its phosphorylation.

The sodium-chloride cotransporter (NCC) in the distal convoluted tubule contributes importantly to sodium balance and blood pressure (BP) regulation. NCC phosphorylation determines transport activity and has a diurnal rhythm influenced by glucocorticoids. Disturbing this rhythm induces "nondipping" BP, an abnormality that increases cardiovascular risk.

Renal and Blood Pressure Response to a High-Salt Diet in Mice With Reduced Global Expression of the Glucocorticoid Receptor.

Salt-sensitive hypertension is common in glucocorticoid excess. Glucocorticoid resistance also presents with hypercortisolemia and hypertension but the relationship between salt intake and blood pressure (BP) is not well defined. GR mice have global glucocorticoid receptor (GR) haploinsufficiency and increased BP.

Glucocorticoids Induce Nondipping Blood Pressure by Activating the Thiazide-Sensitive Cotransporter.

Blood pressure (BP) normally dips during sleep, and nondipping increases cardiovascular risk. Hydrochlorothiazide restores the dipping BP profile in nondipping patients, suggesting that the NaCl cotransporter, NCC, is an important determinant of daily BP variation. NCC activity in cells is regulated by the circadian transcription factor per1.

Blood pressure and sodium: Association with MRI markers in cerebral small vessel disease.

Dietary salt intake and hypertension are associated with increased risk of cardiovascular disease including stroke. We aimed to explore the influence of these factors, together with plasma sodium concentration, in cerebral small vessel disease (SVD). In all, 264 patients with nondisabling cortical or lacunar stroke were recruited.

Hypertrophy in the Distal Convoluted Tubule of an 11β-Hydroxysteroid Dehydrogenase Type 2 Knockout Model.

Na(+) transport in the renal distal convoluted tubule (DCT) by the thiazide-sensitive NaCl cotransporter (NCC) is a major determinant of total body Na(+) and BP. NCC-mediated transport is stimulated by aldosterone, the dominant regulator of chronic Na(+) homeostasis, but the mechanism is controversial. Transport may also be affected by epithelial remodeling, which occurs in the DCT in response to chronic perturbations in electrolyte homeostasis.

Activation of thiazide-sensitive co-transport by angiotensin II in the cyp1a1-Ren2 hypertensive rat.

Transgenic rats with inducible expression of the mouse Ren2 gene were used to elucidate mechanisms leading to the development of hypertension and renal injury. Ren2 transgene activation was induced by administration of a naturally occurring aryl hydrocarbon, indole-3-carbinol (100 mg/kg/day by gastric gavage). Blood pressure and renal parameters were recorded in both conscious and anesthetized (butabarbital sodium; 120 mg/kg IP) rats at selected time-points during the development of hypertension.

Phosphorylation and transport in the Na-K-2Cl cotransporters, NKCC1 and NKCC2A, compared in HEK-293 cells.

Na-K-2Cl cotransporters help determine cell composition and volume. NKCC1 is widely distributed whilst NKCC2 is only found in the kidney where it plays a vital role reabsorbing 20% of filtered NaCl. NKCC2 regulation is poorly understood because of its restricted distribution and difficulties with its expression in mammalian cell cultures.

Functional expression of the Na-K-2Cl cotransporter NKCC2 in mammalian cells fails to confirm the dominant-negative effect of the AF splice variant.

The renal bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2) is the major salt transport pathway in the apical membrane of the mammalian thick ascending limb. It is differentially spliced and the three major variants (A, B, and F) differ in their localization and transport characteristics. Most knowledge about its regulation comes from experiments in Xenopus oocytes as NKCC2 proved difficult to functionally express in a mammalian system.

Cotransporters, WNKs and hypertension: an update.

Purpose Of Review: Studies of inherited conditions characterized by high or low blood pressure reveal the importance of a new signalling cascade, With no Lysine kinases (WNK) --> ste20/SPS1-related proline/alanine-rich kinase (SPAK)/oxidative stress-responsive kinase-1 (OSR1) --> Cation-Chloride Cotransporters (CCC), in regulating blood pressure and in the pathogenesis of essential hypertension. This review explores how these molecules interact to co-ordinate sodium homeostasis and how errors in these interactions may result in hypertension.

Recent Findings: Studies using transgenic animals and gene knockins have clarified the role of mutant WNK4 in hypertension, by revealing its main action to be increasing the expression and activity of sodium-chloride cotransporter (NCC) in the kidney.

Cotransporters, WNKs and hypertension: important leads from the study of monogenetic disorders of blood pressure regulation.

Major advances are being made in identifying the structure and behaviour of regulatory cascades that control the activity of cation-Cl(-) cotransporters and certain Na(+), K(+) and Cl(-) channels. These transporters play key roles in regulating arterial blood pressure as they are not only responsible for NaCl reabsorption in the thick ascending limb and distal tubule of the kidney, but are also involved in regulating smooth muscle Ca(2+) levels. It is now apparent that defects in these transporters, and particularly in the regulatory cascades, cause some monogenetic forms of hypertension and may contribute to essential hypertension and problems with K(+) homoeostasis.

Changes in protein expression in the rat medial vestibular nuclei during vestibular compensation.

The molecular mechanisms of neural and synaptic plasticity in the vestibular nuclei during 'vestibular compensation', the behavioural recovery that follows deafferentation of one inner ear, are largely unknown. In this study we have used differential proteomics techniques to determine changes in protein expression in ipsi-lesional and contra-lesional medial vestibular nuclei (MVN) of rats, 1 week after either sham surgery or unilateral labyrinthectomy (UL). A systematic comparison of 634 protein spots in two-dimensional electrophoresis gels across five experimental conditions revealed 54 spots, containing 26 proteins whose level was significantly altered 1 week post-UL.

Loading rat heart myocytes with Mg2+ using low-[Na+] solutions.

The objective of our study was to investigate how Mg2+ enters mammalian cardiac cells. During this work, we found evidence for a previously undescribed route for Mg2+ entry, and now provide a preliminary account of its properties. Changes in Mg2+ influx into rat ventricular myocytes were deduced from changes in intracellular ionized Mg2+ concentration ([fMg2+]i) measured from the fluorescence of mag-fura-2 loaded into isolated cells.

Sodium-dependent recovery of ionised magnesium concentration following magnesium load in rat heart myocytes.

Our objectives were to investigate regulation of intracellular ionised Mg2+ concentration ([fMg2+]i) in cardiac muscle and cardiac Na+/Mg2+ antiport stoichiometry. [fMg2+]i was measured at 37 degrees C in isolated rat ventricular myocytes with mag-fura-2. Superfusion of myocytes with Na+ and Ca2+ free solutions containing 30 mM Mg2+ for 15 min more than doubled [fMg2+]i from its basal level (0.

Regulation of erythrocyte Na-K-2Cl cotransport by threonine phosphorylation.

A method is described to measure threonine phosphorylation of the Na-K-2Cl cotransporter in ferret erythrocytes using readily available antibodies. We show that most, if not all, cotransporter in these cells is NKCC1, and this was immunoprecipitated with T4. Cotransport rate, measured as 86Rb influx, correlates well with threonine phosphorylation of T4-immunoprecipitated protein.

Activation of ferret erythrocyte Na+-K+-2Cl- cotransport by deoxygenation.

Deoxygenation of ferret erythrocytes stimulates Na+-K+-2Cl- cotransport by 111% (s.d., 46) compared to controls in air.

ATP in the mechanotransduction pathway of normal human chondrocytes.

Extracellular nucleotides have been shown to have diverse effects on chondrocyte function, generally acting via P2 purinoceptors. We have previously shown that mechanical stimulation at 0.33 Hz of normal human chondrocyte cultures causes cellular hyperpolarisation, while chondrocytes derived from osteoarthritic (OA) cartilage depolarise.

Regulation of Na-K-2Cl cotransport by phosphorylation and protein-protein interactions.

The Na-K-2Cl cotransporter plays important roles in cell ion homeostasis and volume control and is particularly important in mediating the movement of ions and thus water across epithelia. In addition to being affected by the concentration of the transported ions, cotransport is affected by cell volume, hormones, growth factors, oxygen tension, and intracellular ionized Mg(2+) concentration. These probably influence transport through three main routes acting in parallel: cotransporter phosphorylation, protein-protein interactions and cell Cl(-) concentration.

DIF signalling and cell fate.

The DIFs are a family of secreted chlorinated molecules that control cell fate during development of Dictyostelium cells in culture and probably during normal development too. They induce stalk cell differentiation and suppress spore cell formation. The biosynthetic and inactivation pathways of DIF-1 (the major bioactivity) have been worked out.

Lithium induced changes in intracellular free magnesium concentration in isolated rat ventricular myocytes.

We have examined the effect of exposing isolated rat ventricular myocytes to lithium while measuring cytosolic free magnesium ([Mg2+]i) and calcium ([Ca2+]i) levels with the fluorescent, ion sensitive probes mag-fura-2 and fura-2. There was a significant rise in [Mg2+]i after a 5 min exposure to a solution in which 50% of the sodium had been replaced by Li+, but not when the sodium had been replaced by bis-dimethylammonium (BDA). However, there were significant increases in [Ca2+]i when either Na+ substitute was used.

Refinement and evaluation of a model of Mg2+ buffering in human red cells.

The total Mg2+ content of human red cells ([Mg]T,i) is partitioned between free and bound forms. The main cytoplasmic Mg2+ buffers are ATP and 2,3 bisphosphoglycerate. Haemoglobin binds free ATP and bisphosphoglycerate, preferentially in the deoxygenated state.

Stimulation of Na+-K+-2Cl- cotransport by arsenite in ferret erythrocytes.

1. Na+-K+-2Cl- cotransport activity was measured in ferret erythrocytes as the bumetanide-sensitive uptake of 86Rb. 2.

Regulation of Na+-K+-2Cl- cotransport by protein phosphorylation in ferret erythrocytes.

1. Na+-K+-2Cl- cotransport in ferret erythrocytes was measured as the bumetanide-sensitive uptake of 86Rb. 2.

Magnesium transport in magnesium-loaded ferret red blood cells.

Mg efflux from ferret red blood cells is stimulated when cells are Mg loaded, but the properties of efflux depend on the loading method. When cell Mg content is altered using A23187, which is subsequently washed away, Mg efflux is minimal until intracellular ionized [Mg] ([Mg2+]i) is greater than 0.9 mM, it then increases substantially with [Mg2+]i.

Na-dependent regulation of intracellular free magnesium concentration in isolated rat ventricular myocytes.

Changes in ionized intracellular free magnesium concentration [Mg2+]i were measured in isolated, superfused rat ventricular myocytes using mag-fura-2. Cells were superfused with media containing high or low Mg concentrations ([Mg]o), with and without Na (Nao) and/or Ca (Cao). Increasing [Mg]o from 1 to 5 mmol/l in Ca-free solutions had no significant effect on [Mg2+]i when [Na]o was normal.