Renal Brush Border Membrane Transport Research Articles

Effect of cystine loading and cystine dimethylester on renal brushborder membrane transport

The effect of loading renal tubule cells with cystine was studied by incubating them with cystine dimethylester. Proline uptake into brushborder membrane vesicles isolated from the cystine loaded cells was not different from that observed into brushborder vesicles isolated from tubules incubated in buffer alone. Incubating brushborder membranes with 2 mM cystine dimethylester for 10 minutes reduced the uptake of proline by 27% after 15 seconds of incubation and by 21% after 60 seconds of incubation. There was no effect after 20 minutes of incubation. Pre-incubating brushborder membrane vesicles with cystine dimethylester had no statistically significant effect on the affinity of proline for the carrier, but did reduce the maximal rate of proline uptake by 49%.

Mechanisms of NAD action in regulation of renal brush border membrane transport of phosphate.

Many different hormonal and non-hormonal stimuli change the rate of phosphate (Pi) transport across the renal brush border membrane (BBM) (1,2, 3) which probably reflects the central role of proximal tubular reabsorption in renal handling of Pi. Based on considerations of (a) the time required for the effects of these stimuli to induce a response, and (b) whether the response is dependent upon intact de novo protein synthesis, it appears that the various stimuli may act intracellularly through at least two general mechanisms (2).

Diuretic effects on renal brush border membrane transport and metabolism

Previous studies have indicated that the thiazide diuretics exert effects on proximal electrolyte transport. To determine whether the locus of these effects is at the brush border membrane (BBM) and if renal metabolism is affected, adult female Sprague-Dawley rats were acutely treated with either 1 mg/kg metolazone, 20 mg/kg chlorothiazide followed by a 20 mg/kg/hr maintenance infusion, 10 mg/kg acetazolamide followed by a 10 mg/kg/hr maintenance infusion, or the vehicles only. Administration of these agents resulted in an approximately tenfold increase in sodium excretion. Neither urinary phosphate nor inulin excretion changed significantly in any group. Sodium dependent BBM vesicle phosphate transport was examined at 0.15, 0.5, and 1 and 120 minute incubation periods in the diuretic treated groups and their respective control groups. Decreased uptake was seen in all pre-equilibrium time points in rats treated with metolazone: 0.15 minutes: 221 ± 24 pmoles/mg protein (pmol/mg prot) in control rats versus (vs) 185 ± 23 pmoles/mg prot in metolazone-treated animals (P < .05); 0.5 minutes: 463 ± 54 vs 369 ± 49 pmol/mg prot (P < .005); 1 minute: 549 ± 74 vs 460 ± 61 pmol/mg prot (P < .05); no significant difference in phosphate transport was noted at the two hour equilibrium time point. No significant differences in sodium dependent phosphate transport existed between chlorothiazide or acetazolamide treated rats and control animals. Substrate-stimulated renal gluconeogenesis did not differ between metolazone treated and control animals. We therefore conclude that metolazone inhibits phosphate transport through an effect on the BBM and does not affect renal gluconeogenesis in the rat.

Thyroid hormones increase renal brush border membrane transport of phosphate in X-linked hypophosphatemic (Hyp) mice.

Hyp mice, the murine homolog of human X-linked hypophosphatemia (XLH), are characterized in part by elevated renal loss of phosphate (Pi) and hypophosphatemia. The lesion responsible for this syndrome is believed to be defective Na+ gradient-dependent phosphate transport across renal brush border membranes (BBM). It has been demonstrated that thyroid hormones can stimulate Pi uptake by rat BBM vesicles (BBMV). The purpose of this current study was to determine whether thyroid hormones could increase renal BBMV transport of Pi and improve the renal conservation of Pi in Hyp mice. Hyp mice were treated with either vehicle (controls) or T4 (0.2 mg/100 g BW, ip, once daily) for 6 days. At the end of the treatment period, the uptake of 32Pi (at 30 sec), in the presence of a Na+ gradient (Na+o greater than Na+i) by BBMV prepared from renal cortex of T4-treated Hyp mice, was significantly increased (+25%) compared to that in vehicle-treated Hyp controls. The uptake of L-[3H]proline (at 10 sec) by the same BBMV preparation was unchanged. T4-treated Hyp mice displayed a significant decrease in urinary Pi excretion (-31%), and a restoration of plasma Pi levels (+52%) to the normal range. Plasma calcium, creatinine, and magnesium as well as urinary excretion of cAMP did not change with T4 treatment. Another group of Hyp mice was given T3 (0.2 mg/100 g BW, ip) at three 12-h intervals. After 36 h, the rate of 32Pi uptake by renal BBM was significantly increased (+40%). Plasma Pi also increased (+26%). Our findings indicate that parenteral administration of thyroid hormones specifically increased (compared to transport of L-proline) the capacity of Na+ gradient-dependent renal BBM Pi uptake in Hyp mice, decreased renal Pi excretion, and increased plasma Pi. These results suggest that treatment with T4 or T3 can enhance the defective proximal tubular reabsorption of Pi and improve renal Pi retention in murine X-linked hypophosphatemia.

Relationship between renal phosphate reabsorption and renal brush-border membrane transport.

Relationship between renal phosphate reabsorption and renal brush-border membrane transport.

Preservation of renal brush border membrane transport function by storage in glycerol

Various methods for the isolation of renal and intestinal brush border membranes have been reported [1]. The isolated membranes vesiculate and are used as model systems to examine the mechanisms by which solutes, for example, sugar and amino acids, are transported into the epithelial cell [2, 3]. Although these studies have provided valuable insight into the transport systems, their general applicability has been limited because of the necessity to measure uptakes on the same day that the membranes are prepared [4], the time required to prepare the membranes being often as long as 5 to 6 hr [5, 6], and the large numbers of small animals (e.g. 20 rats) needed for each preparation [6]. Moreover, the relatively small yield of brush border membranes with each preparation severely hampers efforts to purify sugar and amino acid carriers since the only assay for the carrier in membrane reconstitution studies is transport function itself, rather than catalytic activity, as with cation transporting adenosine triphosphatases [7]. Thus, a procedure for preserving transport function of these membranes is critically needed. Because glycerol and low temperature have been used in other systems to maintain cell integrity and biologic function [8], this technique was examined with isolated renal brush border membranes. In this communication, the preservation of D-glucose and L-proline transport function in stored membranes is reported.

Proximal tubular actions of metolazone and chlorothiazide.

ARTICLESProximal tubular actions of metolazone and chlorothiazidePC Fernandez, and JB PuschettPC Fernandez, and JB PuschettPublished Online:01 Oct 1973https://doi.org/10.1152/ajplegacy.1973.225.4.954MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByPersonalizing the Diuretic Treatment of Hypertension: the Need for More Clinical and Research Attention21 March 2015 | Current Hypertension Reports, Vol. 17, No. 4Distal Convoluted Tubule23 December 2014Physiology and Pathophysiology of Diuretic ActionMetolazone and Its Role in Edema ManagementCongestive Heart Failure, Vol. 9, No. 2DiuretikaDosing of Antihypertensive Medications in Patients with Renal Insufficiency8 March 2013 | The Journal of Clinical Pharmacology, Vol. 35, No. 1Clinical Uses of DiureticsThiazide DiureticsEffects of Diuretics on Renal Function1 January 2011Diuretics in the Therapy of Hypertension: Current StatusThe American Journal of the Medical Sciences, Vol. 304, No. 5Addition of metolazone to overcome tolerance to furosemide in infants with bronchopulmonary dysplasiaThe Journal of Pediatrics, Vol. 120, No. 6Effect of diuretics on cell potassium transport: An electron microprobe studyKidney International, Vol. 37, No. 6Inhibition by volume expansion of phosphate uptake by the renal proximal tubule brush border membraneBiochemical Pharmacology, Vol. 38, No. 2Some Effects of Metolazone on Electrolyte Transport18 January 2010 | Upsala Journal of Medical Sciences, Vol. 92, No. 1Brush Border Membrane Phosphate Transport Effects of Volume ExpansionDiuretic effects on renal brush border membrane transport and metabolismLife Sciences, Vol. 37, No. 18Tubular action of diuretics: Distal effects on electrolyte transport and acidificationKidney International, Vol. 28, No. 3Combined Effect of Bumetanide and Metolazone in Normal Volunteers8 March 2013 | The Journal of Clinical Pharmacology, Vol. 25, No. 5Site and mechanism of the action of diuretics13 March 2009 | Acta Pharmacologica et Toxicologica, Vol. 54Die Anwendung von Diuretika bei der akuten und chronischen HerzinsuffizienzInsights into intrarenal sites and mechanisms of action of diuretic agentsAmerican Heart Journal, Vol. 106, No. 1The pharmacology of diureticsRenal Tubular Secretion and Effects of Chlorothiazide, Hydrochlorothiazide and Clopamide: A Study in the Avian Kidney13 March 2009 | Acta Pharmacologica et Toxicologica, Vol. 51, No. 3Diuretic potency of combined hydrochlorothiazide and furosemide therapy in patients with azotemiaThe American Journal of Medicine, Vol. 72, No. 6Search for pharmaceutically interesting quinazoline derivatives: Efforts and results (1969–1980)Changes in Intrarenal Sodium Handling during Saluretic Treatment in Patients with Essential Hypertension24 April 2009 | Acta Medica Scandinavica, Vol. 210, No. 1-6Role of Extracellular Fluid Volume Expansion and Diuretics in Renal Handling of PhosphateThe Effects of Parathyroid Hormone on Renal Phosphate HandlingMechanism of the Phosphaturia due to ChlorothiazideClearance and micropuncture studies of the diuretic xipamide in dogsEuropean Journal of Pharmacology, Vol. 54, No. 1-2DIURETIC ACTION OF METOLAZONE IN DOGSJapanese Journal of Pharmacology, Vol. 29, No. 1Renal Tubular Effects of Vitamin D and Its Metabolites22 June 2013Kidney Function in Calcium and Phosphate MetabolismSite of action of diuretic drugsKidney International, Vol. 11, No. 1Acute effects of parathyroid hormone on proximal bicarbonate transport in the dogKidney International, Vol. 9, No. 6Metolazone, a diuretic agentAmerican Heart Journal, Vol. 91, No. 2Study of Renal Action of Diuretics by Micropuncture TechniquesRenal function and diuretic therapy in infants and children. Part IIThe Journal of Pediatrics, Vol. 86, No. 5Re-evaluation of microelectrode methodology for the in vitro determination of pH and bicarbonate concentrationKidney International, Vol. 6, No. 2 More from this issue > Volume 225Issue 4October 1973Pages 954-961 Copyright & PermissionsCopyright © 1973 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1973.225.4.954PubMed4743385History Published online 1 October 1973 Published in print 1 October 1973 Metrics