Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Red-cell lithium-sodium countertransport is increased in patients with essential hypertension. It has been proposed that sodium-hydrogen ion exchange in the brush border of the renal proximal tubules is analogous to red-cell countertransport. To investigate the rate of sodium reabsorption by the proximal renal tubules in hypertension, we measured lithium clearance (a measure of proximal tubular reabsorption of sodium), as well as red-cell countertransport, in 14 patients with untreated essential hypertension and in 31 controls. As a group, the hypertensive patients had a higher average (+/- SEM) rate of red-cell countertransport (0.378 +/- 0.030 mmol of lithium per liter of cells per hour, P less than 0.01) and a lower renal fractional lithium clearance (13.96 +/- 0.69 percent, P less than 0.01) than normotensive subjects (0.317 +/- 0.015 mmol of lithium per liter of cells per hour and 17.75 +/- 0.81 percent, respectively). Within the normotensive group, subjects with hypertension in at least one first-degree relative had significantly lower fractional lithium clearances than subjects with no hypertensive relatives (15.37 +/- 0.84 percent vs. 19.06 +/- 1.07 percent, P less than 0.05). We conclude that hypertensive patients have heightened proximal tubular reabsorption of sodium and that red-cell countertransport is a marker of the renal abnormality. Enhanced proximal tubular sodium reabsorption may precede the development of essential hypertension.
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PMID:Red-cell lithium-sodium countertransport and renal lithium clearance in hypertension. 394 8

In a survey the present possibilities are outlined to get knowledge about diseases of inner organs with the help of enzyme determinations in the urine. Here it is remarkable that changes of the enzyme excretion appear not only in renal disease with acute renal failure, pyelonephritis, glomerulonephritis, renal infarction and nephroptosis but are also to be observed in primarily extrarenal diseases such as diabetes mellitus, hyperthyroidism, thesaurismoses, myocardial infarction, hypertension, acute pancreatitis, epidemic hepatitis, liver cirrhosis, obstructive jaundice and rheumatoid arthritis. The causes of the changes of enzyme excretions are various. Since enzymes of different origin and localisation behave themselves variably, the simultaneous determination of a brush border marker (e.g. alanine aminopeptidase), a lysosomal enzyme (e.g. beta-glucuronidase or N-acetyl glucosaminidase) and a low molecular enzyme (e.g. lysozyme) is of use for the recognition of renal alterations. By the control of activities of urinary enzymes it is possible to get without risk informations about pathobiochemical processes in the kidney which are not to be gained by means of other methods.
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PMID:[Urinary enzyme excretion in diseases of the internal organs]. 636 87

Cadmium has been shown to manifest its toxicity in human and animals by mainly accumulating in almost all of the organs and kidney is the main target organ where it is concentrated mainly in cortex. Environmental exposure of cadmium occurs via food, occupational industries, terrestrial and aquatic ecosystem. At molecular level, cadmium interferes with the utilization of essential metals e.g. Ca, Zn, Se, Cr and Fe and deficiencies of these essential metals including protein and vitamins, exaggerate cadmium toxicity, due to its increased absorption through the gut and greater retention in different organs as metallothionein (Cd-Mt). Cadmium transport, across the intestinal and renal brush border membrane vesicles, is carrier mediated and it competes with zinc and calcium. It has been postulated that cadmium shares the same transport system. Cadmium inhibits protein synthesis, carbohydrate metabolism and drug metabolizing enzymes in liver of animals. Chronic environmental exposure of cadmium produces hypertension in experimental animals. Functional changes accompanying cadmium nephropathy include low molecular weight proteinuria which is of tubular origin associated with excess excretion of proteins such as beta 2 microglobulin, metallothionein and high molecular weight proteinuria of glomerular origin (excretion of proteins such as albumin IgG, transferrin etc.). Recent data has shown that metallothionein is more nephrotoxic to animals. Cadmium is also toxic to central nervous system. It causes an alterations of cellular functions in lungs. Cadmium affects both humoral and cell mediated immune response in animals. Cadmium induces metallothionein in liver and kidney but under certain nutritional deficiencies like protein-calorie malnutrition and calcium deficiency, enhanced induction and greater accumulation of cadmium metallothionein has been observed.
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PMID:Molecular basis of cadmium toxicity. 638 35

In contrast to healthy persons, microvillous antigens of the proximal tubule were excreted at an increased rate in patients with kidney diseases as could be shown using specific antisera against brush border (BB) fragments (tissue-proteinuria, histuria). These urinary membrane components were immunologically completely identical with those antigens prepared from isolated kidney cell membranes. A glycoprotein of 240 000 dalton, containing mannose and N-acetylglucosamine was identified as a major immunoreactive constituent of the brush border surface and found to be part of a multienzyme complex. BB-antigens were excreted in urine of patients with glomerulonephritis, hypertension, pyelonephritis, multiple myeloma, after operations, after kidney transplantation, under cytostatic treatment, and after administration of radiopaque agents. Histuria of BB-antigens was significantly higher in patients with multiple myeloma and Bence-Jones-proteinuria compared to those patients where no Bence-Jones L-chains in urine became apparent. Selective kidney angiography and intravenous urography caused a significantly higher output of BB-antigens as compared to the control period (2 p less than 0,005). In a volunteer model, on the basis of BB-histuria, a different nephrotoxic potency of cephalosporins and aminoglycosides arose. In addition, beside soluble BB-antigens, also high molecular weight membrane vesicles were discovered in urine of patients after cytostatic treatment (cis-platinum), after x-ray contrast media, and after kidney transplantation. Both, soluble as well as supramolecular membrane vesicles were isolated from urine applying immunospecific affinity chromatography (anti-BS-agarose beads). Labeled antisera directed against the vesicle material of urine revealed a specific immunofluorescence of cortical tubule only.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Immunodiagnosis of kidney tubular cell injuries using specific anti-membrane antibodies]. 638 21

The abnormal intestinal Ca2+ transport reported in spontaneously hypertensive rats (SHR) has been attributed to decreased responsiveness to calcitriol. We reexamined this hypothesis by studying the calcitriol regulation of SHR duodenal calbindin-D9K and calmodulin and the relation of calcitriol to Ca2+ uptake by isolated enterocytes. SHR and normotensive Wistar-Kyoto (WKY) rats were injected with either 50 ng/d calcitriol (vit-D) or vehicle alone (control) for 3 days. Decreased calbindin-D9K (P < .001) and cellular Ca2+ flux (P < .001) were observed in control SHR. Calcitriol increased total cell and brush border calbindin-D9K (P < .0001); this variation paralleled plasma calcitriol levels in both strains. In contrast, Ca2+ flux, which increased in vit-D animals, remained lower in SHR for plasma calcitriol levels similar to those in WKY rats. Immunoreactive calmodulin was similar in both strains whether assayed in total cell or brush border membranes. In contrast, when measured by ligand blotting (45Ca), calmodulin was lower in SHR than in WKY rats (P < .01), suggesting the existence of a calmodulin pool with reduced Ca2+ binding capacity in the hypertensive strain. Calcitriol had no effect on calmodulin in either strain. In conclusion, Ca2+ binding protein regulation by calcitriol is normal in the SHR, and decreased hormone responsiveness cannot account for the defective duodenal calcium transport of this experimental model of hypertension.
Hypertension 1994 Aug
PMID:In vivo effect of calcitriol on calcium transport and calcium binding proteins in the spontaneously hypertensive rat. 803 41

Inbred Dahl/Rapp salt-sensitive and salt-resistant rats differ in their blood pressure response to dietary salt. We studied sodium-hydrogen (Na-H) exchanger kinetics in renal brush border membrane vesicles prepared from both strains on either a 1% or 8% NaCl diet. Kinetics measurements were made with the acridine orange fluorescence quenching technique in vesicles prepared at pH 6.0. The initial Na-H exchange rate was measured using preparations with similar initial quench values. The maximal transport rate (Vmax, fluorescence units per second per milligram protein [+/- SEM]) in salt-sensitive rats on a 1% NaCl diet was significantly lower than that in salt-resistant rats (36.9 +/- 4.4 versus 51.8 +/- 5.5, respectively, P < .0005). With the 8% NaCl diet for 1 week, the Vmax of salt-resistant rats decreased and became similar to that of salt-sensitive rats. The affinity for sodium (Km, millimoles per liter [+/- SEM]) was also lower in salt-sensitive rats than in salt-resistant rats while on a 1% NaCl diet (11.8 +/- 1.0 versus 19.6 +/- 2.3, respectively, P < .002). These values converged when both strains were fed an 8% NaCl diet for 1 week. Inhibition by 25 mumol/L amiloride was less in salt-sensitive rats than in salt-resistant rats on the 1% NaCl diet. These results show that salt-sensitive rats have lower renal apical membrane Na-H exchange activity than salt-resistant rats on a 1% NaCl diet.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1994 Oct
PMID:Renal apical membrane sodium-hydrogen exchange in genetic salt-sensitive hypertension. 808 17

The present experiment was undertaken to examine the relationship between plasma renin activity and the concentration of angiotensin converting enzyme (ACE) in plasma and renal brush border of Wistar Kyoto rats. Different experimental models known to have opposite effects on plasma renin activity were used: changes in salt intake, the deoxycorticosterone acetate (DOCA) and DOCA-salt models and the two-kidneys one clip (2K1C) model. Two weeks after the start of these experimental series, the rats were killed. At this time, blood pressure did not differ from control group, even in the 2K1C and DOCA-salt groups. As expected, PRAs were highest in the 2K1C and depleted salt groups and lowest in the DOCA, DOCA-salt and high salt groups. No relationship between this wide variation in PRA and change of ACE activity in both plasma and renal brush border could be observed. In the plasma, ACE activity in sodium-depleted rats was slightly decreased whereas no change occurred in the other models. In the kidney, DOCA treatment led to increased ACE activity in the brush border only if the animals were maintained on a high salt intake. DOCA or NaCl alone failed to have this effect. In the 2K1C model, the clipped kidneys exhibited increased brush border ACE activity whereas the unclipped kidneys did not show any significant variation in ACE activity, when compared to sham operated rats. In summary, on one hand these findings show that variations in ACE activity were linked neither to hypertension nor to changes in PRA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Plasma renin activity and angiotensin converting enzyme of renal brush borders]. 812 36

Heparin binding protein-44 (HBP-44) is a heparin binding protein of 44 kDa, found by cDNA cloning using antibodies against teratocarcinoma glycoproteins [Furukawa, T. et al. (1990) J. Biochem. 108, 297-302]. The N-terminal sequence analysis reported in this publication establishes the structure of its mature form. Immunohistochemical staining revealed that HBP-44 was located in the tubular brush border of the kidney. HBP-44 formed a complex with brushin, a high molecular weight (450 kDa) glycoprotein antigen common to the kidney and teratocarcinoma, but not with OR8 antigen, another antigen (350 kDa) of the same category. Brushin was shown to be the mouse counterpart of rat Heymann nephritis antigen, called gp330. The association between HBP-44 and brushin was revealed not only by co-precipitation upon indirect immunoprecipitation, but also by ligand blotting with HBP-44-maltose binding protein fusion protein. Calcium ion stabilized the association. Disulfide bonds in brushin seemed to be necessary for the complex formation, since reductive cleavage of the bonds resulted in failure of the protein to associate with HBP-44 in a ligand blotting experiment. Association of HBP-44 with brushin occurred both in teratocarcinoma cells, in which these molecules are mainly located in extraembryonic endoderm cells, and in the kidney, suggesting that the complex has an unknown common function in the renal tubular brush border and the extraembryonic endoderm.
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PMID:Mouse heparin binding protein-44 (HBP-44) associates with brushin, a high-molecular-weight glycoprotein antigen common to the kidney and teratocarcinomas. 828 24

Angiotensin converting enzyme exists in two different isoforms, somatic and germinal, whose respective distributions and intracellular localizations have not been precisely determined. The differing biochemical and molecular characteristics of the two isozymes allowed the preparation of antibodies specific for each of the two angiotensin converting enzyme isoforms and of two nucleic acid probes, one of which was specific for the germinal isoform. Immunohistochemistry and in situ hybridization were used to determine the cell distribution of, respectively, the two isoforms and their corresponding messenger RNAs in the classically studied tissues of male adult humans and marmosets. Results provided by the two different methods were always concordant and were identical in the two species. The somatic angiotensin converting enzyme form was expressed uniquely in somatic tissues (vascular endothelial cells and at the brush border of renal proximal convoluted tubule, jejunal villus, and epididymal duct epithelia), and the germinal form was expressed uniquely in germinal cells with a precise stage-specific pattern, starting in round spermatids and finishing in spermatozoa. In situ hybridization documented the presence of somatic angiotensin converting enzyme messenger RNA in renal tubule epithelium, jejunal enterocytes, and epididymal epithelium and demonstrated that there was no direct correlation between the levels of angiotensin converting enzyme messenger RNA and the enzyme it encodes for, i.e., angiotensin converting enzyme, in a given epithelium. The significance of the ultraselective expression of germinal angiotensin converting enzyme and of its specific messenger RNA at a very precise stage of spermatogenesis remains uncertain.
Hypertension 1993 Jun
PMID:Gene expression and tissue localization of the two isoforms of angiotensin I converting enzyme. 838 57

Since dopamine produced by the kidney is an intrarenal regulator of sodium transport, an abnormality of the dopaminergic system may be important in the pathogenesis of hypertension. In the spontaneously hypertensive rat (SHR), in spite of normal renal production of dopamine and receptor density, there is defective transduction of the D1 receptor signal in renal proximal tubules, resulting in decreased inhibition of sodium transport (Na+/H+ exchanger [NHE] and Na+/K+ATPase activity) by dopamine. To determine if impaired D1 receptor regulation of NHE in proximal tubules is related to hypertension, studies were performed in a F2 generation from female Wistar Kyoto (WKY) and male SHR crosses. A D1 agonist, SKF 81297, inhibited (37.6 +/- 4.7%) NHE activity in brush border membranes of normotensive F2s (systolic blood pressure < 140 mm Hg, n = 7) but not in hypertensive F2s (n = 21). Furthermore, a D1 agonist, SKF 38393, when infused into the renal artery, dose dependently increased sodium excretion in normotensive F2s (n = 3) without altering renal blood flow but was inactive in hypertensive F2s (n = 21). Since the major D1 receptor gene expressed in renal proximal tubules is the D1A subtype, we determined the importance of this gene in the control of blood pressure in mice lacking functional D1A receptors. Systolic blood pressure was greater in homozygous (n = 6) and heterozygous (n = 5) mice compared to normal sex matched litter mate controls (n = 12); moreover, the mice lacking one or both D1A alleles developed diastolic hypertension. The cosegregation with hypertension of an impaired D1 receptor regulation of renal sodium transport and the development of elevated systolic and diastolic pressure in mice lacking one or both D1A alleles suggest a causal relationship of the D1A receptor gene with hypertension.
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PMID:Role of the D1A dopamine receptor in the pathogenesis of genetic hypertension. 863 8


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