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

Vascular smooth muscle cell hypertrophy is a normal compensatory state that may play a pathogenic role in hypertension. Angiotensin II stimulates a hypertrophic response in cultured vascular smooth muscle cells. As part of the growth response, angiotensin II rapidly activates the Na(+)-H+ exchanger, increasing Na+ influx. Because Na+, K(+)-ATPase is the major cellular mechanism for regulating intracellular Na+, we studied the effects of angiotensin II-induced hypertrophy on Na+, K(+)-ATPase expression and activity. Angiotensin II caused rapid increases in both steady-state Na+, K(+)-ATPase activity (ouabain-sensitive 86Rb uptake) and intracellular [Na+]. Angiotensin II also caused a sustained increase in Na+, K(+)-ATPase at 24 hours with a 73% increase in maximal 86Rb uptake per milligram protein and a fourfold increase in Na+, K(+)-ATPase alpha-1 messenger RNA levels. Thus, angiotensin II hypertrophy was associated with rapid increases in Na+, K(+)-ATPase activity due to increased Na+ entry and sustained increases due to a specific increase in Na+, K(+)-ATPase expression. These data demonstrate dynamic regulation of Na+, K(+)-ATPase at the functional and molecular level and suggest that similar compensatory mechanisms should be present in vivo. Alterations in such compensatory pathways may be fundamental to the pathogenesis of hypertension.
Hypertension 1992 Aug
PMID:Na+, K(+)-adenosine triphosphatase regulation in hypertrophied vascular smooth muscle cells. 132 64

Left ventricular hypertrophy (LVH) is a common condition and a powerful independent risk factor for coronary heart disease, congestive heart failure, and other cardiac morbidity. It is associated with the male sex and advancing age. Its most common cause is hypertension, and many antihypertensive agents induce regression of LVH. Angiotensin-converting enzyme (ACE) inhibitors have been shown to reverse LVH by a mechanism as yet unknown. Reduction in afterload and other hemodynamic abnormalities by reduction of blood pressure is clearly a factor, but ACE inhibitors also block adrenergic action and other sympathetic nervous system influences, and the reduction in angiotensin II produces many effects. By inhibiting this potent vasoconstrictor and suppressing its degradation of the powerful vasodilator bradykinin, and by promoting sodium and water excretion, ACE inhibitors contribute to the restoration of normal ventricular function. Angiotensin II promotes protein synthesis in myocardial myocytes, and blocking this action may arrest the hypertrophic process. To determine the effect of angiotensin II on LVH and normalization of LV function, a study is now underway evaluating the effects of lisinopril, a new lysine analog of enalapril, and a diuretic agent in the treatment of hypertension LVH.
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PMID:ACE inhibitors and regression of left ventricular hypertrophy. 132 1

Factors that can influence cardiovascular growth are becoming increasingly important for our understanding of such complex diseases as cardiac hypertrophy, coronary artery disease, atherosclerosis, and hypertension. Several proto-oncogenes were found to be involved in the regulation of abnormal cell growth in cardiovascular disease. It is also evident that some peptide hormones, which are well known to be involved in blood pressure control, may play a role as growth modulators. Angiotensin II is one such peptide. It elevates blood pressure through its direct vasoconstrictor, sympathomimetic, and (through release of aldosterone) sodium-retaining activity but also appears to have mitogenic actions. Interestingly, all components of the renin-angiotensin system were found locally in cardiovascular tissues. The question remains whether angiotensin can act directly as a growth factor or whether it does so indirectly by influencing or modulating cell growth factors. A better understanding of the renin-angiotensin system as a direct or indirect mediator for cardiovascular hypertrophy would offer new and interesting insights into the pathophysiology of hypertension and possibly novel options for the treatment of cardiovascular disease.
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PMID:The molecular basis of cardiovascular hypertrophy: the role of the renin-angiotensin system. 138 95

Calcium entry blockade may affect the pressor reactivity to vasoconstrictors. The pressor response to norepinephrine and angiotensin II, as well as several other blood pressure modulating factors, were studied in normal subjects (n = 9) and patients with essential hypertension (n = 10) before and after 8 weeks of treatment with the long-acting dihydropyridine amlodipine. In control subjects, calcium entry blockade did not modify blood pressure, the pressor and aldosterone response to angiotensin II, the activity of the renin-angiotensin and sympathetic nervous systems, or urinary dinoprostone (prostaglandin E2) excretion; however, the pressor response to norepinephrine was significantly decreased (p less than 0.01). In patients with hypertension, amlodipine decreased blood pressure (p less than 0.01) and the pressor response to both norepinephrine and angiotensin II (p less than 0.01), without changes in body weight, plasma renin, angiotensin II and catecholamine levels, dinoprostone excretion, or aldosterone responsiveness to angiotensin II. These findings suggest that calcium entry blockade modifies sympathetic-dependent vasoconstriction in both normal subjects and in patients with hypertension. Angiotensin II pressor response may be selectively decreased in essential hypertension.
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PMID:Antihypertensive mechanism of amlodipine in essential hypertension: role of pressor reactivity to norepinephrine and angiotensin II. 138 65

Angiotensin II (Ang II) in low dose raises blood pressure slowly by a mechanism which is not understood, but which is clearly different from the better known direct vasoconstrictor effect. Vascular hypertrophy develops during this slow pressor response, but is not wholly a consequence of the increase of pressure. We discuss non-pressor mechanisms by which Ang II may act as a growth factor to promote structural vascular change. Studies with cultured vascular smooth muscle cells suggest at least three possibilities, but none of these has been tested in vivo during slow pressor infusion of Ang II. The action of growth factors may be important in hypertension since increased arterial pressure causes vascular hypertrophy. Growth factors influence markedly the extent of this hypertrophic response and, however produced, vascular hypertrophy has an important influence on resistance and arterial pressure in hypertension.
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PMID:Angiotensin II, vascular structure and blood pressure. 138 40

We cultured smooth muscle cells from rat renal preglomerular arterioles by injecting a suspension of iron oxide into the left ventricle, separating the arterioles magnetically, and growing cells from explants. In passaged cultures we ascertained vascular smooth muscle purity of > 98% by morphology; contraction to norepinephrine and angiotensin; positive immunofluorescence staining through the sixth passage with monoclonal antibodies to smooth muscle-specific alpha- and gamma-isoactins, myosin, and desmin; and the absence of von Willebrand factor. Angiotensin II (10(-12)-10(-5) M) induced dose-dependent DNA synthesis and proliferation of subcultured (three times) arteriolar smooth muscle cells from a growth-arrested state (p < 0.01). Angiotensin II (10(-5) M) also induced the cells to express c-fos mRNA. We find no previous report of culture of smooth muscle cells from renal preglomerular arterioles. Our findings also provide evidence that angiotensin II is mitogenic to arteriolar muscle cells and thus may be involved in their hyperplasia accompanying hypertension.
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PMID:Culture of renal arteriolar smooth muscle cells. Mitogenic responses to angiotensin II. 139 76

Angiotensin II-induced phosphorylation of proteins was examined in isolated myocytes from hearts of Dahl rats. A high salt diet induced cardiac hypertrophy in Dahl salt-sensitive rats. Angiotensin II-induced phosphorylation of a 42-kd protein (pp42) was detected by two-dimensional electrophoresis in hypertrophic but not normal ventricular myocytes. Angiotensin II stimulation was time-dependent, with a peak effect at 30 minutes. The half-maximal and maximal concentrations of angiotensin II that stimulated pp42 phosphorylation were 1 and 10 nM, respectively. Phosphorylation of pp42 was a function of cardiac hypertrophy. Phorbol 12-myristate 13-acetate-induced phosphorylation of pp42 indicates the possibility of an association between protein kinase C and the signal transduction pathway of angiotensin II-induced pp42 phosphorylation. Ionomycin and A23187 (both at 1 microM) did not stimulate phosphorylation of pp42. Angiotensin II produced a small increase in the synthesis of myocyte proteins in both normal and hypertrophic cells as shown by [35S]methionine incorporation. However, this increase could not account for the increase in the phosphate content of pp42. This protein was not an isoform of actin nor was it of platelet origin. These results raise the possibility that angiotensin II may play a role in the activation of factors in hypertrophic myocytes; however, further study is required to define a link between phosphorylation of pp42 and the hypertrophic process.
Hypertension 1992 Nov
PMID:Angiotensin II-induced protein phosphorylation in the hypertrophic heart of the Dahl rat. 142 15

Transcatheter arterial infusion chemotherapy is one of the most useful therapeutic procedures for gynecologic malignancies. Recently, several reports have been published about Angiotensin II-induced hypertension chemotherapy and the efficacy of the method, but there have been no reports to evaluate an application for gynecologic malignancies. We evaluate the usefulness of the method for gynecologic malignancies demonstrating the changes of hemodynamics of the tumor using 81mKr scintigraphy. Thirteen patients with pathologically confirmed gynecologic malignancies were evaluated by angiography and continuous infusion of 81mKr via the catheter with and without Angiotensin II. At first, continuous infusion of 81mKr was performed under the superselective catheterization of the uterine artery. The radioactivities in the ROI were counted. Then, withdrew the catheter from the uterine artery to the internal iliac artery, and again continuously infused 81mKr and counted the radioactivities in the same ROI. Finally, keeping the catheter in the internal iliac artery, Angiotensin II and 81mKr were infused simultaneously. And counted the radioactivities. The radioactivities were highest when the catheter tip was placed in uterine arteries and lowest when the catheter tip was placed in internal iliac arteries. But radioactivities in the ROIs were definitely increased when Angiotensin II was used, even if the catheter tip was keeping in the internal iliac arteries. The optimal catheter position of transcatheter arterial chemotherapy for gynecologic malignancies is at proximal uterine artery. Since Angiotensin II-induced hypertension may increase blood flow of tumors, it seems to have indication for post-operative cases, highly advanced cases and cases with difficulties to perform superselective catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[81mKr scintigraphic evaluation of hemodynamics in gynecologic malignancies under condition of angiotensin II-induced hypertension]. 143 80

We have previously shown that the stimulatory effects of guanine nucleotides, N-ethylcarboxamide-adenosine and other agonists on adenylate cyclase activity were diminished in aorta and heart sarcolemma of spontaneously hypertensive rats (SHR) [Anand-Srivastava (1988) Biochem. Pharmacol. 37, 3017-3022]. In the present studies, we have examined whether the decreased response of these agonists is due to the defective GTP-binding proteins (G-proteins) which couple the receptors to adenylate cyclase, and have therefore measured the levels of G-proteins in aorta and heart from SHR and their respective Wistar-Kyoto (WKY) controls by using pertussis toxin (PT)- and cholera toxin (CT)-catalysed ADP-ribosylations and immunoblotting techniques using specific antibodies against G-proteins. The labelling with [32P]NAD+ and PT identified a 40/41 kDa protein in heart and aorta from WKY and SHR and was significantly increased in the hearts (approximately 100%) and aorta (approximately 30-40%), from SHR as compared with WKY. Immunoblotting revealed an increase in the levels of the G-protein alpha-subunits Gi alpha-2 and Gi alpha-3 in heart and Gi alpha-2 in aorta, whereas no change in Go alpha was observed in heart from SHR and WKY. On the other hand, no differences were observed in CT labelling or immunoblotting of stimulatory G-protein (Gs) in heart and aorta from WKY and SHR. In addition, CT stimulated the adenylate cyclase activity in heart sarcolemma from WKY and SHR to a similar extent. These results were correlated with adenylate cyclase inhibition and stimulation by various hormones. Angiotensin II (AII), atrial natriuretic factor (ANF) and oxotremorine-mediated inhibition was found to be greater in SHR as compared with WKY, whereas the stimulatory effects of adrenaline, isoprenaline, dopamine and forskolin were diminished in SHR aorta as compared to WKY. These results indicate that regulatory protein G(i) is more expressed in SHR, which may be associated with the decreased responsiveness of stimulatory hormones and increased sensitivity of inhibitory hormones to stimulate/inhibit adenylate cyclase activity. It may thus be suggested that the enhanced G(i) activity may be one of the mechanisms responsible for the diminished vascular tone and impaired myocardial functions in hypertension.
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PMID:Enhanced expression of inhibitory guanine nucleotide regulatory protein in spontaneously hypertensive rats. Relationship to adenylate cyclase inhibition. 144 83

Angiotensin II is a potent pressor hormone and a primary regulator of aldosterone secretion. It acts through at least two types of receptors termed AT1 and AT2. We analyzed cDNA and genomic clones encoding the human angiotensin II type-1 receptor, AT1. The human AT1 gene was mapped to chromosome 3q by polymerase chain reaction analysis of DNA from a panel of human-hamster somatic cell hybrids. The predicted amino acid sequence is 95% identical to the corresponding rat and bovine receptors and 25% and 22% identical, respectively, to the receptors encoded by the RTA and MAS genes. Characterization of several human cDNA clones demonstrated the existence of two alternate 5'-untranslated regions (UTRs) that contain a common initial sequence but differ by the presence or absence of an insertion of 84 base pairs. In the genomic sequence, the coding sequences are contained in a single exon, with an intron occurring in the 5'-UTR at the position of insertion of the 84-base pair sequence. The exons encoding the alternate 5'-UTRs are located at least 3.8 kilobases away from the exon encoding the protein. Reverse transcription-polymerase chain reaction analysis showed that both forms of 5'-UTR are present in approximately equal abundance in a range of tissues expressing AT1. The reagents developed in this work may be useful in testing the hypothesis that genetic variations in angiotensin II receptor function are associated with a tendency to develop hypertension.
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PMID:Genetic analysis of the human type-1 angiotensin II receptor. 150 24


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