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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Basolateral membrane (BLM) enriched fraction was isolated from homogenized rat kidney cortex by differential centrifugation. We also obtained a fraction enriched in plasma membrane (PM). The morphology of the isolated BLM fragments was studied by transmission and freeze fracture electron microscopy. The relative specific activity of Na+-K+-ATPase was enriched 7-fold, while that of marker enzymes for PM, endoplasmic reticulum, and lysosomes was lower than in the crude homogenate. There was a 10-fold difference in the ratios of activities of Na+-k+-ATPase to Mg2+-ATPase in the BLM and in the PM enriched fractions. Kallikrein activity was determined with S-2266 substrate and by radioimmunoassay of kinin released. It was low in the BLM fraction prior to adding detergent, but Triton X-100 increased the activity 12 to 16-fold. Both free trypsin and Sepharose 4B-bound insoluble trypsin increased kallikrein activity 2- to 3-fold in both the membrane-bound and soluble fractions, probably by activating a prekallikrein. The results were interpreted that the kallikrein studied originated from the distal tubular BLM.
Hypertension
PMID:Kallikrein and prekallikrein on the basolateral membrane of rat kidney tubules. 627 73

Microsomal fractions enriched in plasma membranes and endoplasmic reticulum were isolated from stomach fundus and vas deferens from age-matched Okamoto spontaneously hypertensive (SHR) rats and corresponding Kyoto-Wistar normotensive rats (KWR). Alterations of several enzyme activities and Ca2+ accumulation of the isolated microsomal fraction from these nonvascular smooth muscles provide direct evidence of abnormal smooth muscle membrane biochemistry in SHR. Decreased Ca2+ accumulation in the presence of but not in the absence of adenosine triphosphate by the microsomal fractions of both fundus and vas deferens from SHR is consistent with previous findings using plasma membranes from vascular smooth muscles from SHR and cannot be explained in terms of adaptation induced by elevation of blood pressure in SHR. Defective Ca2+ handling now observed in both vascular and nonvascular smooth muscles from hypertensive animals not only provides a cellular basis for the altered reactivity and contractility of smooth muscles observed in SHR, but also supports the hypothesis that spontaneous hypertension is associated with a generalized widespread alteration in smooth muscle membrane fraction.
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PMID:Abnormal biochemistry of subcellular membranes isolated from nonvascular smooth muscles of spontaneously hypertensive rats. 628 45

The left coronary artery of 21-, 28-, and 45-day-old spontaneously hypertensive rats and Wistar-Kyoto rats was analyzed morphometrically to evaluate the structural alterations of the vessel wall during the development of genetically determined hypertension. In 45-day-old rats, hypertension was associated with a significant expansion of the partial volume of collagen and ground substance (119%) within the arterial wall. This change exceeded the concurrent accumulation of elastin (77%) and smooth muscle cell mass (34%). The growth of the muscle compartment was also characterized by a marked increment of rough endoplasmic reticulum (103%). The increase in the mural concentration of fibrous proteins at this early age may be viewed as the initial adverse effect of hypertension on muscular arteries.
Hypertension
PMID:Connective tissue accumulation in the left coronary artery of young SHR. 674 84

Tissue, cellular, and subcellular morphometry of the thoracic aorta in 1-, 5- and 11-day-old rats was used to quantify the cellular hypertrophy and proliferation of smooth muscle cells and the absolute increases in volume of elastic laminase and collagen during the early postnatal period. In the 1- to 5-day interval, total wall volume increased 2.9-fold, wall thickness and the number of smooth muscle cells doubled, mean cell volume increased by 40%, and the volumes of elastic laminae and collagen increased 3.7- and 3.3-fold, respectively. From 5 to 11 days, circumferential growth of the aortic wall, without further thickening, produced smaller and unequal growth increments of each of its component structures, with increases in collagen (3.2-fold) > elastic laminae (2.3-fold) > muscle cells (1.6-fold). In the overall growth of smooth muscle cells (4.6-fold) from 1 to 11 days, only the cytoplasmic volume fractions of glycogen aggregates and rough endoplasmic reticulum were altered significantly (-76%, +32%). Certain aspects of normal postnatal aortic growth paralleled the response of adult aorta to experimentally induced hypertension.
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PMID:Morphometric study of early postnatal development of the thoracic aorta in the rat. 740 24

The pathogenesis of acute pancreatitis is poorly understood, despite well-recognised precipitating factors. Current evidence suggests that the earliest abnormalities of acute pancreatitis arise within acinar cells, but the key intracellular trigger has yet to be identified. Within the pancreas, physiological concentrations of secretagogues bind to G-protein-linked cell-surface receptors on acinar cells, evoking short, oscillatory spikes of acinar cytosolic-free ionised calcium ([Ca2+]i), an ubiquitous intracellular messenger. Specific effects within acinar cells include initiation of enzyme release through the phosphorylation cascades of stimulus-secretion coupling. Low resting levels of [Ca2+]i are restored by Ca(2+)-ATPase, which pumps calcium into the endoplasmic reticulum and out of the cell. If high concentrations of [Ca2+]i persist, toxicity results, intracellular signalling is disrupted, and cell damage occurs. Sustained elevations in acinar [Ca2+]i result from exposure to high concentrations of secretagogues, high doses of which also induce acute pancreatitis. Similarly, sustained elevations of [Ca2+]i may result from ductal hypertension, alcohol, hypoxia, hypercalcaemia, hyperlipidaemia, viral infection, and various drugs--all factors known to precipitate acute pancreatitis. We suggest that these factors precipitate acute pancreatitis by causing either excessive release of acinar [Ca2+]i, or damage to the integrity of mechanisms that restore low resting levels of [Ca2+]i, and that the consequent calcium toxicity is the key trigger in the pathogenesis of acute pancreatitis.
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PMID:Is an elevated concentration of acinar cytosolic free ionised calcium the trigger for acute pancreatitis? 747 53

In 15 adult cats the bridging draining into the superior sagittal sinus as well as their main tributaries were dissected under surgical microscope and ligated. Samples of tissue from cerebral cortex (CC) and subcortical white matter (SWM) with presumed disturbances of venous outflow were investigated by means of electron microscopy following different survival times (ranging from 3 to 15 days). The examination of the ultrathin sections from the CC and SWM disclosed signs of severe oedema: extensive areas of oedema fluid accumulation, swollen dendrited and synaptic endings, neurones with mitochondria destruction, disorganised endoplasmic reticulum and polysomal aggregates, prominent number of vacuoles, dendrites undergoing correspondent changes, degenerating axons and synaptic endings. The conspicuous presence of erythrocytes usually in perivascular zones of the neuropil, occluded, ruptured or collapsed capillaries having vacuoles in their endothelial cells were frequently encountered. These findings confirm the light microscopial observations demonstrating haemorrhagic infarctions after venous occlusions. They provide ultrastructural details about the CC and SWM changes resulting from venous hypertension and hypoperfusion.
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PMID:Ultrastructural study of cerebral cortex and subcortical white matter following ligation of bridging veins in cats. 748 90

Many properties of urinary kallikrein are well characterized, but the intracellular processing of prokallikrein and release by kidney cells have yet to be clarified. We report here on the synthesis of prokallikrein in Madin-Darby canine kidney (MDCK) cells transfected with rat submaxillary gland kallikrein cDNA and on its activation by MDCK cells and by an enriched liver Golgi membrane preparation. Transfected MDCK cells secreted only prokallikrein at both the apical and basolateral sides in about a 4:1 ratio, but cells transfected with kallikrein cDNA in reverse orientation or untreated cells released only traces of the enzyme. Prokallikrein, in culture medium or in homogenized MDCK cells, was fully activated by trypsin but activated only to 44% by thermolysin. Prokallikrein was synthesized and released into the medium at a high rate: the enzyme secreted by 5 x 10(6) cells in 24 hours cleaved 46 nmol/min D-Val-Leu-Arg-7-amino-4-methylcoumarin and liberated 63 ng/min bradykinin after activation. Immunocytology indicated the association of prokallikrein with the Golgi apparatus in the transfected cells. Antiserum to rat urinary kallikrein detected a single band in a Western blot of conditioned medium and also immunoprecipitated the enzyme. Aprotinin inhibited activated prokallikrein. Although MDCK cells released prokallikrein, their homogenates activated prokallikrein at both pH 5.5 and 7.5. Prokallikrein was also activated by a highly enriched liver Golgi membrane fraction and by an endoplasmic reticulum preparation, but the Golgi preparation was 38-fold more active. The activation was blocked significantly by inhibitors of serine proteases and less by cysteine protease inhibitors.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1995 Dec
PMID:Expression of rat kallikrein and epithelial polarity in transfected Madin-Darby canine kidney cells. 749 Jan 45

The receptor-associated protein (RAP) specifically associates with gp330 and the low density lipoprotein (LDL) receptor-related protein (LRP), the two newest members of the LDL receptor gene family. Results obtained by ligand blotting, affinity chromatography, and density-gradient sedimentation demonstrate that RAP binds to both receptors with high affinity and that the binding is Ca2+ dependent. RAP also binds heparin and is identical to a mouse heparin binding protein (HBP-44) identified in a teratocarcinoma cell line (F9). While biochemical studies have shown that RAP is present on the cell surface and is an effective inhibitor of ligand binding to gp330 and LRP, immunocytochemical findings indicate that RAP is most abundant in the endoplasmic reticulum lumen and may function in receptor folding and/or trafficking. To facilitate the characterization of RAP's function(s) we have mapped its gp330 and heparin binding sites by performing direct binding studies on fusion proteins representing overlapping domains of RAP. gp330 was found to bind to two separate sites on RAP--i.e., between amino acids 85-148 and 178-248. Binding studies with radiolabeled heparin indicate that the heparin binding site is between amino acids 261 and 323, which is consistent with our previously proposed site (residues 287-306) based on the amphipathic nature of the C terminus of RAP. These data demonstrate that the gp330 and heparin binding sites and the Heymann nephritis pathogenic epitope (amino acids 1-86) demonstrated earlier are represented by distinct domains of the RAP polypeptide.
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PMID:Functional domains of the receptor-associated protein (RAP). 751 26

The authors report five patients with adrenal cortical tumors in whom the preoperative diagnosis of pheochromocytoma was made. All patients had biochemical evidence of elevated catecholamine secretion in serum or urine. Clinically, two patients presented with symptoms suggestive of pheochromocytoma, and one patient had systemic hypertension that resolved following surgical excision of the tumor. Histologically, the findings were typical of adrenal cortical tumors: two adrenal cortical carcinomas and three adrenal cortical adenomas. Nevertheless, the immunohistochemical studies showed evidence of neuroendocrine differentiation in four tumors. Three tumors were positive for neuron-specific enolase and synaptophysin and a fourth tumor was positive for synaptophysin only. All neoplasms were negative for chromogranin. Electron microscopic studies in three tumors showed abundant endoplasmic reticulum and tubulovesicular cristae consistent with adrenal cortical cell origin. Neurosecretory granules, 150-300 mu in diameter, were found in one tumor. This current series of patients provides evidence that adrenal cortical neoplasms may be associated with clinical findings that simulate pheochromocytoma (so-called pseudo-pheochromocytoma). These clinical findings may be mediated by the presence of neuroendocrine features in these tumors.
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PMID:Adrenal cortical tumors clinically mimicking pheochromocytoma. 757 86

The use of platelets instead of smooth muscle cells (SMC) to study the abnormal Ca2+ handling found in hypertension was investigated using spontaneously hypertensive rats (SHR). We studied the regulation of platelet Ca(2+)-ATPases, as we have recently demonstrated that human platelets, like SMC, contain the Ca(2+)-ATPase isoform termed SERCA2-b (sarco-endoplasmic reticulum Ca(2+)-ATPase). In mixed membranes isolated from platelets of normotensive Wistar-Kyoto (WKY) rats and SHR, total Ca(2+)-ATPase activity was found to be 43% higher in SHR than in WKY rats. By the use of autophosphorylation of rat platelet Ca(2+)-ATPases with [gamma-32P]ATP, followed by SDS/PAGE and Western blotting, we found that rat platelets express two distinct Ca(2+)-ATPases: a 100 kDa isoform, recognized by a SERCA2-b-specific anti-peptide antibody, and a 97 kDa isoform, specifically recognized by a polyclonal anti-SERCA antibody. Comparative analysis of platelet membrane Ca(2+)-ATPases from WKY rats and SHR demonstrated that the expression of the SERCA2-b isoform did not change significantly (128 +/- 22%), whereas that of the 97 kDa isoform reached 300 +/- 35% in SHR when compared with WKY rats. We concluded that the upregulation of total platelet Ca(2+)-ATPases in SHR is not due to the 100 kDa SERCA2-b isoform found in SMC, but is specific to the 97 kDa Ca(2+)-ATPase isoform which is not present in SMC. Therefore platelets should be used with extreme caution as a surrogate model of vascular smooth muscle Ca2+ homeostasis.
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PMID:Spontaneously hypertensive rats and platelet Ca(2+)-ATPases: specific up-regulation of the 97 kDa isoform. 824 Feb 78


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