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

Current knowledge of the links between the sympathetic nervous system and vascular damage in hypertension and atherosclerosis is summarized. The main mechanisms leading to the structural changes of the arterial wall as a consequence of enhanced adrenergic drive are reported. Hemodynamic mechanisms, including increase in pressure leading to changes in the arterioles and alteration of flow pattern with impact mainly in the large arteries, respectively, account for the typical target organ damage observed in hypertension and is involved in the development of atherosclerotic lesions. Regarding the direct effect of catecholamines, the atherogenic effects of epinephrine and norepinephrine in the absence of changes in blood pressure and cholesterol levels have been demonstrated in vivo in monkeys and rabbits. In rats, catecholamine administration induces polyploidization of aortic smooth muscle cells in vivo and in vitro. Regarding the effects of lipid metabolism, adrenergic stimulation may induce free fatty acid transformation into triglycerides with secondary increase in very low density lipoprotein plasma levels and decrease of very low density lipoprotein transformation into high density lipoprotein through circulating lipoprotein lipase inhibition. Catecholamines may also increase cholesterol levels of the arterial wall, probably by triggering the acyl-cholesterol-acyl-transferase activity. Finally, indirect evidence of the pathogenetic role played by the sympathetic system in the development of vascular disease derives from the results of experiments showing that sympatholytic agents are capable of reducing both medial hypertrophy and atherogenesis. beta-Blockers, alpha- and beta-blockers, and centrally acting sympatholytic agents not only ameliorate hemodynamics but also appear to inhibit the direct effects of catecholamines on the arterial wall.
Hypertension 1991 Apr
PMID:Sympathetic drive and vascular damage in hypertension and atherosclerosis. 201 98

Hypertension that occurs before the age of 60 years is strongly aggregated in families, mostly due to genetic factors with weaker contributions from a shared family environment. Hypertension is probably a heterogeneous collection of overlapping subsets of pathophysiological mechanisms, such as dyslipidemia, obesity, hyperinsulinemia and cation metabolism. Highly heritable traits such as sodium-lithium countertransport, urinary kallikrein excretion and a body fat pattern index show evidence of major gene segregation in families with hypertension. They are thought to be intermediate phenotypes in the chain of pathophysiological events leading from specific genes to the distant phenotype of hypertension. They provide evidence of measurable contributions from single gene traits to the susceptibility to hypertension. Genetic linkage studies have suggested that other specific loci (e.g. histocompatibility leukocyte antigen, blood group MN and the haptoglobin protein) contribute to the susceptibility to hypertension. DNA sequencing has shown a point mutation for lipoprotein lipase that conveys susceptibility to lipid abnormalities, and possibly also hypertension, as seen in families with dyslipidemic hypertension. Further application of these approaches, especially in families that include multiple siblings with hypertension, shows promise of a true understanding of how the combined effects of a few specific genes, the polygenic background and selected environmental factors can lead to essential hypertension. This understanding should foster better tailored and more effective approaches to the prevention, diagnosis and treatment of hypertension.
 ...
PMID:Multigenic human hypertension: evidence for subtypes and hope for haplotypes. 209 95

Recent studies have shown the predictive power of abdominal distribution of adipose tissue for the development of cardiovascular disease, stroke, diabetes as well as strong associations to the previously known risk factors for these endpoints. The reason for the accumulation of abdominal fat might be due to an imbalance between cortisol and sex steroid hormones. Cortisol receptor density seems to be particularly high in abdominal adipose tissue, leading to expression of lipoprotein lipase activity primarily here. Progesterone and testosterone seems to counteract this, the former perhaps through competition with the cortisol receptor. Accumulation of intraabdominal fat, particularly in the tissues drained by the portal circulation, probably leads to high free fatty acid concentrations in the portal vein, because of the high lipolytic sensitivity of these tissues. This in turn seems to inhibit hepatic clearance of portal insulin, leading to peripheral hyperinsulinemia, insulin resistance, perhaps hypertension as well as hyperlipidemia via drive by free fatty acids of lipoprotein synthesis in the liver. These are risk factors for diabetes, cardiovascular disease and stroke. It is of interest that subjects with abdominal adipose tissue have several factors leading to increased cortisol and low sex steroid hormone secretion, including stress, high alcohol consumption and smoking. This might provide some of the background to this syndrome.
 ...
PMID:Obesity and adipose tissue distribution as risk factors for the development of disease. A review. 214 Jan 8

Several drugs used in the treatment of hypertension have been shown to affect lipid metabolism. A few studies have examined in detail the effects of calcium antagonists on blood lipids. We investigated the effects of nifedipine and nitrendipine on blood lipids using two experimental protocols. The first study was a double-blind, randomized, placebo-controlled trial to assess the effects of acute oral administration of nifedipine 10 mg on blood lipids in 10 patients (9 males, 1 female; age range 26-50 years) with mild hypertriglyceridemia. Serum triglycerides were not significantly affected (from 310 +/- 120 to 280 +/- 110 mg/dl 2 h after nifedipine) but a slight decrease was observed in patients with higher baseline levels. In the second study, an intravenous fat tolerance test (ivFTT, Intralipid 10%, 1 ml/kg body weight, as a bolus) was performed before and after chronic oral administration of nitrendipine 10 mg b.i.d. in 10 mild to moderate hypertensive patients (7 males, 3 females; age range 40-60 years). After nitrendipine treatment, the fractional removal rate (K2) of the lipid emulsion was significantly increased from 3.1 +/- 0.9 to 3.8 +/- 0.9% min (p less than 0.05). The main findings of these studies suggest that the secretion of lipoprotein lipase might be stimulated by calcium antagonists. Alternatively, the vasodilation produced by these compounds may influence triglyceride removal by expanding the capillary bed where the enzyme exerts its activity. In conclusion, calcium antagonists do not seem to cause unwanted side effects on blood lipids and apparently enhance triglyceride removal.
 ...
PMID:Acute and chronic effects of dihydropyridines on triglycerides in humans. 246 58

Anthropometric, endocrine and metabolic variables, were examined in women with polycystic ovarian syndrome (PCO), and in normal control women. Obese women with PCO had higher plasma insulin values than non obese women with PCO, but lean body mass, glucose tolerance, plasma triglycerides and blood pressure were not different in spite of almost twice the body fat mass in the obese PCO women. However, in comparisons between non-obese PCO and control women, with equal body fat mass, the PCO women had higher blood pressure, plasma triglycerides and insulin, as well as a tendency to increased lean body mass. Both PCO groups had a high waist/hip ratio and larger abdominal fat cells than controls, indicating a preferential abdominal accumulation of adipose tissue. In comparison with abdominal adipocytes, femoral adipocytes were larger and had higher lipoprotein lipase activity in the control women, while in the PCO women these regional differences were not found. Basal and norepinephrine stimulated lipolysis were higher in the abdominal than femoral adipocytes in all groups. Substitution of the PCO women with ethinyl estradiol plus desogestrel during 6 months resulted in a regression of clinical androgenic symptoms as well as a normalization of plasma concentrations of free testosterone and sex hormone binding globulin. However, neither body composition nor metabolism were normalized. It was concluded that body fat distribution is more closely related to hypertension and metabolic derangements than total fat mass in the PCO syndrome. It is suggested that the relative paucity of femoral adipose tissue is due to a lack of specific effects of progesterone on adipocytes in this region.
 ...
PMID:Anthropometric variables and metabolism in polycystic ovarian disease. 277 99

There is good epidemiologic evidence that hypertension is associated with a high risk of cardiovascular disease. However, primary intervention trials have failed to demonstrate that a reduction in blood pressure in hypertensive patients reduces morbidity and mortality from cardiac events. Since various antihypertensive drugs adversely affect lipoprotein metabolism, these drugs may increase associated coronary risk and offset the beneficial effects of lowering blood pressure. This article reviews the effects of various antihypertensive drugs on plasma lipids, lipoproteins, and apolipoproteins. They can be summarized as follows: thiazide-type diuretics cause a marked elevation of plasma triglycerides and very low-density lipoprotein (VLDL) and minor increases in total cholesterol and low-density lipoprotein (LDL), but have little effects on high-density lipoprotein (HDL). The nonselective beta-blockers do not significantly affect total cholesterol and LDL, but increase total triglycerides and VLDL and decrease HDL. The changes in plasma lipids and lipoproteins caused by cardioselective beta-blockers and beta-blockers with intrinsic sympathomimetic activity are qualitatively similar but less pronounced. Calcium antagonists and angiotensin-converting enzyme inhibitors appear to have no significant effects on plasma lipids. alpha 1-Inhibitors reduce total triglycerides, total cholesterol, VLDL, and LDL and increase HDL. The possible mechanisms by which antihypertensive drugs affect cellular lipid metabolism (e.g., LDL receptor, lipid synthesis, lipoprotein lipase, lecithin cholesteryl acyltransferase, acylcholesteryl acyltransferase, and cholesteryl ester hydrolase) are described. The clinical significance of changes in blood lipids and cellular lipid metabolism caused by antihypertensive drugs is not yet totally clear. Nevertheless, before antihypertensive drug treatment is initiated, blood lipid levels should be measured to identify preexisting hyperlipidemia.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Effects of antihypertensives on plasma lipids and lipoprotein metabolism. 305 88

In summary, both the developing atherosclerotic and FSGS lesions seem to share certain postulated pathophysiologic mechanisms, including endothelial cell injury, macrophage infiltration, hyperlipoproteinemia, and hypertension. As depicted in Figure 1, any initial glomerular injury results in flux of macromolecular substances into the glomerular mesangium. As an adjunct to increased glomerular barrier dysfunction, hyperlipoproteinemia is believed to secondarily develop from the dramatic losses of albumin, stimulating increased hepatic lipoprotein synthesis and the loss of lipoprotein lipase-activating substance into the urine which would effectively produce a reduction in circulating chylomicra and triglyceride catabolism. Certain elevated circulating lipoproteins could, theoretically, pass through the damaged glomerular filter into the mesangium, thereby enhancing the flux of macromolecules. Also associated with certain experimental glomerular disorders is the development of glomerular hypertension, as manifested by an elevated glomerular capillary hydrostatic pressure (PGC), which can further augment macromolecular flux into the mesangium. Overloading of the glomerular mesangium by the above mechanisms is believed to be an injurious stimulus for MC to both proliferate and produce excess mesangial matrix substance. Both of these events are thought to be pathologic harbingers of glomerulosclerosis. Glomerular hypertension is also capable of damaging endothelial cells within the glomerular microcirculation, and this purportedly can activate platelets and result in glomerular thrombosis. At present, it is unclear how glomerular thrombosis produces increased mesangial cell injury; however, this process is believed to cause both systemic and glomerular hypertension which may serve as intermediary mechanisms producing the untoward effects of mesangial cell proliferation and matrix overproduction.
 ...
PMID:Focal and segmental glomerulosclerosis: analogies to atherosclerosis. 329 16

Phospholipase C activity and diglyceride lipase activity were studied in the renal cortex and medulla of 10- and 40-week-old stroke-prone spontaneously hypertensive rats (SHRSP) and age-matched normotensive Wistar-Kyoto rats (WKY). Enhanced phospholipase C activity was found in the cortical and medullary cytosol of kidney from SHRSP, and microsomal diglyceride lipase in SHRSP also increased. In SHRSP, phospholipase C and diglyceride lipase activities increased with age, but this increase was not evident in WKY. Phospholipase C had high substrate specificity for phosphatidylinositol in renal cytosol of both WKY and SHRSP. The increased activities were accompanied by prostaglandin E2 synthesis in renal medullary microsomes of 10-week-old SHRSP and were also present in the kidney of 40-week-old SHRSP. Total phospholipid and arachidonic acid contents in kidney were markedly high in the medulla of 10-week-old SHRSP, but these lipids were decreased in 40-week-old SHRSP. These results suggest that phospholipids and arachidonic acid in SHRSP may be genetically high and that the activated phospholipase C and diglyceride lipase hydrolyze phospholipids, providing arachidonic acid for prostaglandin synthesis, which results in a decrease of phospholipids and arachidonic acid in the kidney of 40-week-old SHRSP. These studies demonstrate that a phosphatidylinositol-specific phospholipase C-prostaglandin synthetic system may play an important role in the course of hypertension in SHRSP.
Hypertension 1987 Jul
PMID:Renal phospholipase C and diglyceride lipase activity in spontaneously hypertensive rats. 347 8

The possible role of Mg in the pathogenesis of vascular disease has recently received increasing attention. Accumulating evidence indicates that Mg strongly influences vascular tone and responsiveness to pressor agents and that Mg deficiency may be associated with an increased risk of hypertension. Moreover, experimental Mg deficiency produces vascular lesions with calcifications while increasing the dietary intake of Mg has been shown to prevent atheroma and thrombotic complications. The modifications of lipid metabolism during experimental Mg deficiency have been recently characterized. Severe Mg deficiency in weanling rats produces a marked hypertriglyceridemia and a decrease in the percentage of cholesterol transported by high-density lipoprotein. The decreased clearance of circulating triglycerides appears to be the major mechanism contributing to hyperlipemia. The same animals were found to have a reduced insulin response after intravenous glucose challenge and a slight reduction in heparin release lipoprotein lipase. A marked reduction in plasma activity of LCAT and a significant decrease in esterified/total plasma cholesterol ratio have also been reported. Severe Mg deficiency in weanling rats produces marked changes in the fatty acid pattern of total plasma lipids, as shown by decreased levels of stearic acid, increased of oleic acid and linoleic acid, and decreased levels of arachidonic acid. Platelets from Mg-deficient rats become more sensitive to thrombin. Such an increased sensitivity of platelets may in turn play an important role in initiating the vascular lesion as well as in thrombotic complications. In view of these experimental data in animal models, more work seems necessary in man to assess the effect of Mg on lipid metabolism and vascular disease.
 ...
PMID:Magnesium, lipids and vascular diseases. Experimental evidence in animal models. 352 56

The effects of labetalol on serum lipoproteins, the intravenous fat tolerance test (IVFTT) and lipoprotein lipase (LPL) and hepatic lipase (HL) activities were studied in 16 patients with mild hypertension before and after 6 months of therapy. Most patients were found to be normotensive on 200 mg labetalol/day. Before therapy the mean concentration of serum TG was 0.75 +/- 0.21 (SD) mmol/l, of total cholesterol 5.41 +/- 1.25 mmol/l and of HDL cholesterol 1.67 +/- 0.61 mmol/l. After labetalol no significant changes were found in the concentrations of TG and cholesterol in the VLDL, LDL and HDL fractions. The mean values for the IVFTT and for LPL and HL activities were in the normal range and remained unchanged during therapy.
 ...
PMID:Effects of long-term therapy with labetalol on lipoprotein metabolism in patients with mild hypertension. 405 May 51


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>