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

Microsomal fractions were isolated from the smooth muscle of gastric fundus, vasa deferentia and mesenteric arteries of rats made hypertensive by deoxycorticosterone-salt treatment. Several enzymatic activities, Ca2+ binding and ATP-dependent Ca2+ accumulation of the microsomal fractions from these hypertensive rats were compared with those from the control of rats which remained normotensive under similar treatment. Altered membrane properties were observed in microsomal fractions isolated from vascular smooth muscle but not in those isolated from non-vascular smooth muscles in this form of experimental hypertension. These alterations included decreased Mg2+ ATPase activity, enhanced alkaline phosphatase activity, decreased Ca2+ binding in the absence of ATP and decreased ATP-dependent Ca2+ accumulation. This result is in contrast to our previous findings that decreased ATP-dependent Ca2+ accumulation was observed in microsomal fraction isolated from non-vascular smooth muscles of rats with genetic hypertension. The present study, together with our previous findings, support the contention that altered Ca2+ handling by vascular smooth muscle is associated with the pathogenesis of hypertension, whereas altered Ca2+ handling by non-vascular smooth muscles previously observed in spontaneous hypertension may be associated with genetic factors not related to hypertension.
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PMID:Membrane abnormalities occur in vascular smooth muscle but not in non-vascular smooth muscle from rats with deoxycorticosterone-salt induced hypertension. 668 Oct 43

This is the first report of the successful use of magnesium sulfate (MgSO4) in 3 consecutive patients with torsades de pointes (TdP). In 1 patient, TdP was induced by a combination of quinidine and amiodarone, in the second by procainamide, and in the third by an overdose of imipramine. The QT intervals before TdP were 0.70, 0.64 and 0.56 second, respectively. A bolus of 1.0 to 2.0 g MgSO4 25% abolished the TdP in all 3 patients; but in the third patient, because of recurrent TdP, a second bolus of 1.0 g and a continuous 24-hour infusion of 1.0 mg/min were administered, preventing TdP. There was no immediate shortening in the QT interval in any patient after MgSO4. Magnesium can be given safely even in patients with acute myocardial infarction, angina pectoris or systemic hypertension, conditions in which isoproterenol is contraindicated; it can be applied faster than temporary cardiac pacing; and its use for TdP appears worthy of additional trials.
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PMID:Magnesium therapy for torsades de pointes. 669 82

We examined sera from 159 patients with ischemic heart disease and hypertension and from 50 apparently healthy control subjects for content of trace elements, cholesterol, triglyceride, and enzymes. Concentrations of copper, cobalt, cholesterol, and triglyceride were increased in all patients, but calcium was decreased in patients with hypertension, acute myocardial ischemia, and acute myocardial infarction. Also accompanying acute myocardial infarction were decreased concentrations of zinc and iron but increases in nickel, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. Magnesium concentration was lower in patients with acute myocardial ischemia. In acute myocardial infarction, the concentrations of copper, zinc, and iron were higher after 21-30 h (as compared with the values at 0-10 h), by which time concentrations of calcium, magnesium, cobalt, and alanine aminotransferase had decreased. The variation in concentration of trace elements in serum from cases of ischemic heart disease and hypertension corresponds to the severity of the disorder.
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PMID:Trace elements in serum from Pakistani patients with acute and chronic ischemic heart disease and hypertension. 671 25

A reliable and simple uptake test is proposed to assess the activity of the sodium lithium (Na+-Li+) countertransport and the sodium-potassium (Na+-K+) cotransport system of human erythrocytes. The test consists in measurement of phloretin-sensitive Li+ uptake from magnesium (Mg2+) media containing 2 mM Li+ and of furosemide-sensitive rubidium (Rb+) uptake from Na+ media containing 5 mM Rb+. Both Li+ and Rb+ are determined by atomic absorption spectrophotometry. The particular experimental conditions of the uptake assay are analyzed with respect to parameters that potentially affect the results, such as pH, cell volume, internal Na+, external Na+ and Rb+, presence of other ions, and concentration and protein-binding of furosemide, respectively. It is found that the activity of the two transport systems varies more than threefold among normotensive individuals, the activities in erythrocytes of each individual donor remaining stable within +/- 10% over more than two red cell life spans. The Li+ and Rb+ uptake rates are highly correlated to Li+ and K+ or Na+ release rates as determined by the methods of Canessa et al. and Garay et al. The test can thus be applied for routine screening in the search of "abnormalities" of red cell cation transport in hypertensive patients.
Hypertension
PMID:Sodium-lithium exchange and sodium-potassium cotransport in human erythrocytes. Part 1: Evaluation of a simple uptake test to assess the activity of the two transport systems. 715 28

In-vitro experiments are presented which indicate that the concentration of extracellular magnesium ions ([Mg2+]o) can exert profound influences on the contractility and reactivity of arteries, arterioles and veins from a number of regional vasculatures in several mammalian species, including man. Hypomagnesemia can potentiate the contractile activity of a variety of neurohumoral substances and induce vasospasm. Hypermagnesemia can do the reverse, i.e., induce hyporeactivity, relaxation and vasodilatation. Data are also presented to indicate that [Mg2+]o can control the entry, distribution and exit of calcium ions (Ca2+) from vascular smooth muscle cells. Arterial and venous smooth muscles excised from rats with alloxan-diabetes mellitus or spontaneous hypertension (SHR) appear to exhibit vascular membranes which have modifications in their Mg-Ca exchange sites. Data are reviewed which suggest that certain vascular diseases (e.g., sudden-death ischemic heart disease, hypertension, eclampsia, diabetes mellitus) are associated with a Mg-deficiency. Overall, it is suggested that [Mg2+]o and membrane [Mg] may play critical roles in regulating vascular tone and homeostasis.
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PMID:Hypomagnesemia and vasoconstriction: possible relationship to etiology of sudden death ischemic heart disease and hypertensive vascular diseases. 730 71

Previous work has shown that parathyroidectomy lessens hypertension if performed on young SHR (5-6 weeks of age). In this work, ionic changes (Na+, K+, Ca2+, Mg2+) were studied in heart and aorta during a chronic experimentation. In the heart, atria and ventricle, Ca2+ content was significantly diminished, 15 days after parathyroidectomy. Nevertheless after 8 months, this difference did not remain. A correlation between Ca2+ content and heart rate (lessened immediately after parathyroidectomy) is suggested. In the aorta, parathyroidectomy did not change Na+, K+, Ca2+ and Mg2+ content after 15 days. At the opposite Mg2+ content was significantly lessened after 8 months (-33 p. 100, p less than 0,001). Calcium content in the Lanthanum Resistant Fraction was also depressed significantly at this time. Variations in heart and aorta ionic contents are discussed in relation with hypertensive development.
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PMID:[Parathyroidectomy and calcium exchange in cardiovascular tissue in the SHR rat]. 732 10

Prostaglandins (PGs) may play an important role in the pathogenesis of hypertension via their effects on vascular smooth muscle tone. It has been suggested that the capacitance (venous) vessels in the peripheral circulation exhibit an increased tone in the development of hypertension. Recent findings from our laboratory indicate that magnesium ions ([Mg2+]o) play a role in the control of vascular tone, vascular reactivity and Ca2+ content and its distribution in blood vessels. The present study indicates that reactivity of isolated portal venous smooth muscle, obtained from spontaneously hypertensive rats, is markedly reduced in the absence of [Mg2+]o. In addition, our findings indicate that portal venous smooth muscle from age-matched inbred Wistar-Kyoto, but not from normal age-matched Wistar controls, also exhibits decreased responsiveness to PGs in the absence of [Mg2+]o. These new data suggest that Mg2+ may be an important and overlooked factor in the etiology of hypertensive vascular disease.
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PMID:Magnesium ions control prostaglandin reactivity of venous smooth muscle from spontaneously hypertensive rats. 739 65

The properties and characteristics of acyl-CoA synthetase from the arterial wall of rats were investigated. The enzyme is located mainly in the microsomes. Its activity was found to be maximal at pH 7.0-8.0, and to be completely dependent on ATP, CoASH and Mg2+. The Km values for these substances were the same as those of the enzyme in liver. The activity was affected by serum, divalent cations, albumin, lipoproteins and phospholipids. In rats, the activity was decreased in various pathological conditions, such as tocopherol deficiency, hypertension and diabetes mellitus and was increased in hypercholesterolemia. The physiological significance of this enzyme in free fatty acid metabolism is discussed on the basis of these results.
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PMID:Studies on acyl-CoA synthetase in rat arterial wall. 745 88

A history of alcohol abuse associated with hypertension and chronic alcohol consumption is the leading cause of secondary cardiomyopathy. Both acute and chronic alcohol consumption precipitate arrhythmias. However moderate alcohol intake exerts a protective effect against coronary heart disease and stroke. Morbidity is lowest among light drinkers, slightly higher among lifelong abstainers and much higher among heavy drinkers. Magnesium deficiency is common among chronic alcoholics and frequent in Brazil. Magnesium therapy may have beneficial effects when there is excessive ethanol consumption.
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PMID:[Cardiovascular impact of alcoholism]. 748 61

In this randomized controlled trial comparing FK-506 to CsA, we report parameters of nephrotoxicity in adult patients surviving > 90 days after orthotopic liver transplant (OLT). Patients randomized to FK-506 first received 0.15 mg/kg IV/day followed by 0.3 mg/kg PO/day. Doses were modified to avoid toxicity and to achieve FK-506 levels of 0.5 to 1.5 ng/ml. CsA was administered in the usual manner with dose adjustments to whole blood HPLC levels. A pre-OLT glomerular filtration rate (GFR) of > or = 30 ml/min/1.73/m2 and/or serum creatinine < or = 2.0 mg/dl were required for inclusion in the study. GFRs were obtained at post OLT days 28, 180, and 360. Other parameters of renal function evaluated were creatinine, magnesium, serum electrolytes, blood pressure, use of antihypertensives, and magnesium supplements. There were 38 patients in the FK-506 group and 34 in the CsA group. The mean days of follow up for each group was similar: 456 +/- 135 days for the FK-506 group and 451 +/- 112 days for the CsA group. The mean oral dose for the FK-506 group ranged from 0.13-0.16 mg/kg/day with mean FK-506 levels of 0.6-0.8 ng/ml. In the FK-506 group, there was a significant fall in the pre-transplant GFR from 89 +/- 31 ml/min/173 m2 to 43 +/- 15 ml/min/173 m2 at day 360. Similarly, for the CsA group, the pre-transplant GFR of 75 +/- 31 ml/min/1.73 m2 fell to 49 +/- 17 ml/min/1.73 m2 at day 360. At each time point studied, there was no significant difference in mean GFR between the two groups. There were no significant differences in the monthly mean values for creatinine, electrolytes, magnesium, or blood pressure between the two groups. Magnesium levels were in the low normal range (1.4-1.6 mEq/L), and the mean potassium levels in the high normal range (4.4-4.7 mEq/L). In both groups, a similar number of patients required magnesium supplementation or hypertensive medications. The nephrotoxicity of FK-506 given at low oral doses and with concomitant low levels was comparable to that of CsA. The two drugs were remarkably similar in their spectrum of electrolyte disturbances and incidence of hypertension.
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PMID:A comparison of renal function in cyclosporine- and FK-506-treated patients after primary orthotopic liver transplantation. 769 36


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