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

In suspensions of permeabilized human neutrophils, the free Ca2+ concentration was measured to test the effects of ciclosporin. Free Ca2+ concentration was measured with a Ca2(+)-selective electrode. Ciclosporin (500 ng/ml) induced a transient increase in free Ca2+ concentration (maximum delta pCa, 0.41 +/- 0.17). Thereafter, the free Ca2+ concentration decreased again, but did not reach the baseline level in most experiments. Ruthenium red, but not orthovanadate, abolished the slow decline of free Ca2+ concentration after the initial increase. The experiments suggest that ciclosporin may induce a release of Ca2+ from cellular organelles, e.g. the endoplasmic reticulum, and a partial reuptake in mitochondria. A release of cellular Ca2+ may play a role in ciclosporin-induced hypertension.
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PMID:Ca2+ release in permeabilized human neutrophils induced by ciclosporin. 170 Mar 14

The present study was designed to investigate calcium uptake by the intestinal endoplasmic reticulum in the spontaneously hypertensive rat (SHR) and its genetically matched normotensive control, the Wistar-Kyoto rat (WKY). The calcium uptake was characterized before (weanling) and after (adult) development of hypertension in SHR and their age-matched WKY controls. Adenosine 5'-triphosphate (ATP)-driven calcium uptake with time was stimulated several-fold compared with the no-ATP condition, and the maximal uptake occurred after 15 min in both SHR and WKY. The maximal ATP-dependent calcium uptake was significantly greater in the intestinal endoplasmic reticulum of adult SHR than in that of WKY (P less than 0.05). The initial rate of calcium uptake was linear up to 30 s in both SHR and WKY. The kinetics of ATP-dependent calcium uptake at a concentration between 0.1 and 1.0 mumol/l showed a maximal uptake (Vmax) of 1.89 +/- 0.3 and 1.06 +/- 0.1 nmol/mg protein per 15 s for adult SHR and WKY, respectively (P less than 0.02), and binding constant (Km) values of 0.15 +/- 0.08 and 0.12 +/- 0.05 mumol/l, respectively. The ontogeny of calcium uptake by intestinal endoplasmic reticulum was characterized before the development of hypertension in weanling (3-week-old) SHR and WKY. In both SHR and WKY weanlings, calcium uptake by the intestinal endoplasmic reticulum was enhanced several-fold by the presence of ATP compared with the no-ATP condition, and the maximal uptake occurred after 15 min. The maximal ATP-dependent calcium uptake was significantly greater in 3-week-old SHR than in age-matched WKY (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intestinal calcium transport in spontaneously hypertensive rats and their genetically matched Wistar-Kyoto rats. I. Endoplasmic reticulum. 216 23

Extensive bodies of literature describe protein synthesis and processing; the endocrinology and metabolic bases whereby a variety of hormonal, mechanical, and nutritional influences affect cell function and adaptive responses; and various regulatory mechanisms mediating concerted intracellular control. Nonetheless, our current understanding of the mechanisms responsible for the regulation and subordination of protein synthesis to the overall metabolic and stimulus-response status of the cell is inadequate. The endoplasmic reticulum is central to these concerns. Potential roles of the endoplasmic reticulum in the regulation of protein synthesis are largely unexplored. We have attempted in this rather speculative review, based largely on our own data, to project a view of the endoplasmic reticulum as moderating the rate of translation through a mechanism sensitive to sequestered Ca2+. Compensatory routes whereby cells accommodate to Ca2+ deprivation so as to resume reasonable rates of protein synthesis are seen also to focus on the endoplasmic reticulum. With additional research, the underlying relationships that exist among reticular Ca2+ storage, protein processing, and mechanisms of translational control should become more broadly evident. The prevailing view of Ca2+ as a regulator of cytosolic processes may require some extension if sequestered Ca2+ participates in biological control mechanisms emanating from the endoplasmic reticulum. In effect, a reciprocal relationship would presumably exist among processes supported by cytosolic free Ca2+ vs those promoted by sequestered stores of the cation. Speculatively, such reciprocity would allow the rapid diversion of energy from one set of processes to the other. Conceivably, chronic Ca2+ loading at sequestered sites may be related to certain cellular adaptive Ca2+ loading involving tissue hypertrophy. Potential examples of stretch-induced responses that could be cited include thickening of arteriolar smooth muscle walls in hypertension (8) and cardiac hypertrophy in aortic stenosis (46).
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PMID:Calcium-dependent regulation of protein synthesis in intact mammalian cells. 218 68

The placenta and the umbilical cord obtained from 18 women with pregnancy-induced hypertension were investigated by light microscopy. The umbilical artery was studied by electron microscopy. 10 placentae and umbilical cords from normal pregnancies served as controls. The study was performed as a double-blind randomized controlled study in which 11 women were allocated to magnesium and 7 to placebo treatment. The treatment comprised a 48-hour intravenous magnesium/placebo infusion followed by daily oral magnesium/placebo intake until one day after delivery. Magnesium supplement increased birth weight and placental weight significantly. Light microscopic study of the placentae and the umbilical cord arteries showed no difference between the three groups concerning the occurrence of infarctions, cytotrophoblastic hyperplasia, vasculo-syncytial membranes, basement membrane thickening, stromal fibrosis or intervillous fibrin. Ultrastructurally, the endothelial cells of the umbilical arteries from women with pregnancy-induced hypertension showed a significant increase in the amount of dilated endoplasmic reticulum and basal laminae thickness when all 18 cases were compared with the controls. There was no significant difference when the magnesium group, the placebo group and the control group were compared separately. The present study suggests that magnesium supplement has a beneficial effect on fetal growth in pregnancy-induced hypertension. With regard to the light and electron microscopic changes we were unable to demonstrate any significant difference between the magnesium, placebo and control groups.
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PMID:Magnesium supplement in pregnancy-induced hypertension. A clinicopathological study. 228 7

We have investigated the relative importance of renal renin stores and de novo synthesis during stimulation of renin secretion and the role of transcription and posttranscriptional factors in providing increased synthesis of renin. When enalapril was administered to previously untreated mice, plasma renin concentration increased 40-fold within 1.5 hours, and remained at a high level for the 8 days of the experiment. Renal renin decreased by 82% after 24 hours and thereafter increased to levels higher than controls. Calculations of renin turnover, based on data for the rate of metabolism of renin in plasma, indicated that most of the renin released in the first 24 hours could be accounted for by the decrease in renal renin stores, indicating that de novo synthesis played only a minor role. After 24 hours, however, when both plasma renin concentration and renal renin increased, the calculated rate of renin synthesis increased to nearly 40 times the rate in controls. When enalapril was administered to mice that had been depleted of plasma and renal renin by chronic sodium loading, plasma renin concentration increased markedly within 1.5 hours, but to only half the level achieved in the previously untreated mice. No decrease in renal renin occurred, suggesting that the renal renin remaining after chronic sodium loading was not available for release. Renal renin messenger RNA increased 4.5-fold after 6 hours, and after 8 days had increased to 5.0 times the level at day 0. The increase in calculated rate of renin synthesis was maximal between 5 and 8 days, when it was 54 times greater than at day 0. During enalapril treatment, there were marked increases in the granulation of the juxtaglomerular cells and in the amount of rough endoplasmic reticulum and Golgi apparatus they contained. These results suggest that posttranscriptional factors play a major role in determining the rate of renin synthesis.
Hypertension 1989 Oct
PMID:Effect of converting enzyme inhibition on renin synthesis and secretion in mice. 255 20

Primary tumor of the aorta is extremely rare. An instance of aortic intimal sarcoma, namely fibromyxosarcoma, which extended from the beginning of the descending aorta to 7 cm above the abdominal bifurcation, with clinical evidence of acutely occurring hypertension, arterial embolism of the lower extremities, renal infarction, and aortic occlusion in a 50-year-old male is reported. The tumor was limited to the intima and composed of spindle-shaped tumor cells with abundant myxoid extracellular matrices. The tumor cells were negative for Factor VIII, Desmin, or Myoglobin, but were positive for Vimentin or Factor XIIIa in immunoperoxidase studies. An electron microscopic examination revealed a large amount of rough endoplasmic reticulum in the cytoplasm. Parenchymal metastases were observed in both the lungs and thoracic vertebrae. A review of literature on the clinical and pathological aspects of the tumor was made.
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PMID:A case of aortic intimal sarcoma manifested with acutely occurring hypertension and aortic occlusion. 258 79

Many hormones, neurotransmitters, and secretagogues act by increasing the intracellular free Ca2+ concentration in target cells. The initial event following binding of agonists to specific receptors in the plasma membrane involves a receptor-mediated activation of a guanosine nucleotide-binding protein (G protein), which induces a Ca2+-independent activation of phospholipase C. This novel, presently uncharacterized G protein is inactivated by pertussis toxin-catalyzed adenosine 5'-diphosphate ribosylation in some but not all cell types. Phospholipase C catalyzes the breakdown of inositol lipids, notably phosphatidylinositol 4,5-bisphosphate, with the production of inositol phosphates and 1,2-diacylglycerol. Inositol 1,4,5-trisphosphate (IP3) is responsible for a rapid mobilization of intracellular Ca2+ by activating Ca2+ efflux from a subpopulation of the endoplasmic reticulum. The properties of this process are consistent with its being a ligand-activated ion channel with electrogenic Ca2+ efflux being charge-compensated by K+ influx. Sustained hormonal responses require extracellular Ca2+ and a prolonged elevation of the cytosolic free Ca2+. This is brought about by hormone-mediated changes of Ca2+ flux across the plasma membrane involving both an inhibition of Ca2+ efflux and an activation of Ca2+ influx. This review summarizes recent findings concerning the role of G proteins in receptor coupling to phospholipase C; the regulation of enzymes of phosphoinositide metabolism; the evidence for IP3 being a Ca2+-mobilizing second messenger and its mechanism of action; the formation of new inositol phosphates and their possible significance; the relation of intracellular Ca2+ mobilization and plasma membrane Ca2+ fluxes to the kinetics of the hormone-induced cytosolic free Ca2+ transient; and the possible roles of protein kinase C in influencing the hormone-mediated functional response.
Hypertension 1986 Jun
PMID:Role of inositol lipid breakdown in the generation of intracellular signals. State of the art lecture. 301 67

The distribution of calcium in the mitochondria of the adrenal gland was studied during development of adrenal regeneration hypertension. Electron opaque precipitate (calcium antimonate) was localized predominantly in the intercristal space within mitochondria and in cisternae of smooth endoplasmic reticulum. Stereological techniques were employed to quantitate the volume per cell of precipitate. Compared to the zona glomerulosa or zona fasciculata of controls, the volume per cell of electron opaque precipitate in mitochondria of the regenerating gland was significantly reduced at 5 and 14 days after enucleation. By 21 days, the volume of mitochondrial precipitate per cell, while more than that in zona glomerulosa cells, was less than in mitochondria from control zona fasciculata cells. As a comparison, normal rats were treated with ACTH or were hypophysectomized. ACTH-treatment did not greatly increase the precipitate associated with mitochondria in the zona fasciculata. Mitochondria in the zona fasciculata of hypophysectomized rats however showed a significant reduction in precipitate per cell correlating with a significantly reduced volume of mitochondria per cell as compared to those of control zona fasciculata cells. Giant mitochondria were observed in hypophysectomized animals. Volume of precipitate per cell associated with smooth endoplasmic reticulum was increased slightly, but significantly, as compared to that in controls treated with ACTH, whereas in hypophysectomized rats, it was decreased significantly. Adrenocortical cells arising from the zona glomerulosa and sub zona glomerulosa region differentiate to zona fasciculata cells during regeneration and may have an altered capacity to concentrate calcium. Change in intramitochondrial calcium may be correlated with the reduced formation of corticosterone from its precursor, deoxycorticosterone, thereby contributing to the pathogenesis of adrenal regeneration hypertension.
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PMID:Cytochemical localization of calcium in mitochondria of regenerating rat adrenal cortex. A study of adrenal regeneration hypertension. 356 Feb 95

Cultivated aortic smooth muscle cells (SMC) derived from normotensive and hypertensive rats were analyzed by transmission electron microscopy and ultrastructural morphometry. SMC cultures obtained from hypertensive rats showed an increase in cell size and a higher percentage of large, often polynuclear cells. The stereological data of mitochondria, rough endoplasmic reticulum (RER) and secondary lysosomes were determined by measuring area according to the "Delesse principle". The organelle contents of small and large cells of each group were only slightly different. Significant changes were found between SMC from normotensive and hypertensive rats: The volume density Vv of mitochondria per unit cytoplasm volume was increased up to 48% in small and 50% in large SMC from hypertensive rats compared to those of control animals. The numerical density Nv of secondary lysosomes per unit cytoplasm volume was increased up to 68% in small and 267% in large SMC from hypertensive rats. The content of rough endoplasmic reticulum varied tremendously between the individual cells. All these stereological data represent relative parameters of cell organelles relative to the unit cytoplasm volume. Therefore the differences between the absolute values would be even higher since SMC from hypertensive rats are shown to have a higher mean cell size and volume. We conclude that the effect of experimental hypertension, resulting in an activation of SMC, persists even when the cells are transferred to in vitro conditions.
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PMID:Ultrastructural morphometry of cultivated smooth muscle cells from normotensive and hypertensive rats. 403 80

Female, uninephrectomized rats injected with methylandrostenediol became hypertensive by 4 weeks of treatment. After cessation of treatment, blood pressure continued to rise during the first week but gradually decreased below the borderline of hypertension by 5 weeks. After methylandrostenediol treatment for 4 weeks and after 1 week of recovery, adrenocortical fine structure exhibited a number of abnormalities including reduced numbers of mitochondrial cristae, hypertrophic smooth endoplasmic reticulum, microfilaments and large lipid vacuoles within zona reticularis cells. During an intermediate period of recovery (2 weeks), mitochondrial cristae increased in number, although animals remained hypertensive. After 2 weeks, all of the ultrastructural abnormalities seen at early and intermediate periods of recovery were fully reversed, concomitant with a return of systolic blood pressure to below hypertensive levels.
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PMID:Recovery of adrenal ultrastructure after cessation of androgen treatment. 432 34


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