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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Rapid effects of hormones on the metabolism of glycogen and fatty acids were studied in the perfused liver of normal and genetically obese (ob/ob) mice. 2. In livers from normal and obese mice adrenaline and angiotensin II stimulated glycogenolysis. 3. These hormones inhibited the synthesis de novo of long-chain fatty acids in livers from normal mice, but not in livers from obese mice. 4. The proportion of acetyl-CoA carboxylase in the active form was decreased by adrenaline but not by angiotensin II in livers from obese mice. 5. The potency of hormone effects on liver suggests that they could occur in the intact animal. 6. The results add to the evidence that hepatic fatty acid synthesis in genetically obese (ob/ob) mice is irreversibly resistant to inhibition by a range of hormones. Such resistance could be of primary significance in the pathogenesis of the obesity.
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PMID:Catabolic effects of adrenaline and angiotensin II in the perfused liver of normal and genetically obese (ob/ob) mice. 3 34

1. Intra-arterial pressure was recorded continuously in 26 patients with uncomplicated essential hypertension under standardized conditions. Pressure was analysed beat by beat by computer and variability measured as the standard deviation of the normally distributed frequency histogram. 2. Variability was strongly influenced by physical activity, being least during sleep and increasing progressively with bed rest and ambulation. Variability during daytime was not related to time. 3. Systolic variability correlated directly with systolic pressure. An independent inverse relationship with baroreflex sensitivity was observed. Systolic variability tended to increase with obesity. 4. None of the following were related independently with variability: age; race; sex; plasma renin activity; plasma angiotensin II; plasma noradrenaline; plasma adrenaline.
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PMID:Factors determining the variability of arterial pressure in hypertension. 39 78

The incidence of hypertension is increased in obesity, a state associated with an insulin resistance syndrome. By using an euglycemic clamp method, Ferrannini et al. demonstrated the existence of an insulin resistance state in patients with essential hypertension. However, the body mass index of the subjects studied appeared to be slightly excessive. This abnormality has not been observed in patients with secondary hypertension. Insulin resistance is probably localized to peripheral tissues such as muscles and may be associated with other cellular abnormalities. Can insulin resistance, characterized by a raised circulating insulin concentration in the presence of normal blood glucose, be responsible for certain "modifications" associated with essential hypertension? Insulin induces sodium retention and increases the aldosterone-secreting effect of angiotensin II. These effects are likely to promote a rise in blood pressure and an increase in the sensitivity of vessels to endogenous substances. Moreover, insulin is a known growth factor and is involved in lipoprotein metabolism. If insulin resistance plays an important role in the maintenance of complications of essential hypertension, it is important that the treatments used tend to correct this anomaly. Thiazide diuretics and beta-blockers aggravate insulin resistance while angiotensin converting-enzyme inhibitors correct this condition.
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PMID:[Arterial hypertension, hyperinsulinism and insulin resistance]. 143

Recent work to elucidate the cause of obesity-associated hypertension has focused on insulin resistance and hyperinsulinemia. A significant amount of epidemiologic and correlational evidence suggests a link between these factors and obesity-associated hypertension, and acute insulin infusion studies have revealed renal, neural, and cardiovascular effects of this hormone that, if maintained chronically, could cause hypertension. However, correlations and acute effects may not reliably predict a chronic cause-and-effect relationship, and the fundamental question of whether chronic increases in plasma insulin concentration per se can produce a sustained increase in arterial pressure has not been completely resolved. Recent studies designed to address this question directly have found no evidence of a hypertensive effect of insulin in normal dogs, or in dogs with a 70% reduction in kidney mass and given a high sodium intake. Chronic hyperinsulinemia also did not potentiate the pressor effects of angiotensin II or norepinephrine. In fact, hyperinsulinemia caused significant reductions in total peripheral vascular resistance in dogs and a decrease in arterial pressure. Furthermore, induction of insulin resistance in dogs made obese by being fed a high-fat diet eliminated the decrease in peripheral vascular resistance during chronic insulin infusion but did not uncover a pressor effect of hyperinsulinemia. In contrast, insulin infusion for up to 7 days produced a sustained increase in arterial pressure in rats. Although the mechanism for this pressor response is unknown, these data indicate either that there are major species differences in the chronic blood pressure response to insulin or that specific, presently unknown, conditions must exist in order for insulin to raise blood pressure. Also, it is not clear whether humans respond more like rats or dogs with respect to blood pressure changes during chronic hyperinsulinemia. However, it is apparent that obesity hypertension is probably much too complex to be ascribed to insulin resistance and hyperinsulinemia alone.
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PMID:Insulin resistance, hyperinsulinemia, and obesity-associated hypertension. 148 47

Hyperinsulinemia and insulin resistance have been postulated to link obesity and hypertension. Evidence supporting this concept derives mainly from epidemiological studies showing a correlation between insulin resistance, hyperinsulinemia, and blood pressure and from short-term studies suggesting that insulin has renal and cardiovascular actions that, if sustained, could elevate blood pressure. However, a cause-and-effect relation between insulin and hypertension has not been clearly established. Recent studies indicate that chronic hyperinsulinemia, similar to that found in obese hypertensive patients, did not raise blood pressure in normal dogs, even when renal excretory capability was reduced by prior removal of kidney mass. Chronic insulin infusion also failed to elevate blood pressure in dogs maintained on a high sodium intake and did not potentiate the long-term blood pressure responses to angiotensin II or norepinephrine. The presence or absence of insulin resistance may not be a major factor in determining the blood pressure response to hyperinsulinemia since chronic insulin infusion also failed to cause hypertension in obese, insulin-resistant dogs. Although hyperinsulinemia causes transient sodium retention, sustained decreases in renal excretory capability sufficient to cause chronic hypertension did not occur in dogs. In rats, insulin infusion causes small increases in blood pressure, although several characteristics of the hypertension (e.g., salt-sensitivity) differ from those observed in obese human hypertensive patients. Whether humans more closely resemble dogs or rats with respect to their long-term cardiovascular responses to insulin remains to be determined. However, very high insulin levels in humans with insulinoma do not cause hypertension, and several studies suggest that there is only a weak correlation between plasma insulin concentration and blood pressure in normal humans. Therefore, additional factors besides hyperinsulinemia per se may be responsible for a major component of obesity-associated hypertension.
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PMID:Obesity-associated hypertension. Hyperinsulinemia and renal mechanisms. 173 Apr 54

Hyperinsulinemia has been implicated in the pathogenesis of the blood pressure elevation in patients with noninsulin-dependent diabetes mellitus, obesity, but also essential hypertension. In these conditions an increased cardiovascular reactivity to noradrenaline (NA) and angiotensin II (AII) can be observed. Using the euglycemic clamp technique, we determined the cardiovascular reactivity to graded infusions of NA and AII in nine healthy males before (Bas), and 1 and 6 h after infusion of insulin (50 mU/kg per h) was started. On separate days control experiments were carried out to control for any circadian variation. Insulin led to a decrease of the amount of circulating NA necessary to increase the diastolic blood pressure (DBP) 20 mmHg (actual experiment [mean +/- SEM]: Bas, 23.1 +/- 5.0; 1 h, 14.8 +/- 3.0; and 6 h, 12.3 +/- 3.1; and control experiment: Bas, 20.7 +/- 5.0; 1 h, 18.6 +/- 3.5; and 6 h, 17.3 +/- 3.3 nmol/liter; Bas vs. 1 and 6 h: P less than 0.05). Although the amount of NA infused to raise DBP 20 mmHg showed a similar decline after 1 h of insulin infusion, no such change from baseline could be observed at 6 h. This appeared to be due to an increase in NA clearance with more prolonged insulin infusion. Insulin exerted no effect on the amount of AII infused to increase DBP 20 mmHg (actual experiment: Bas, 27.6 +/- 6.4; 1 h, 28.8 +/- 10.0; and 6 h, 21.2 +/- 5.3; and control experiment: Bas, 33.6 +/- 5.7; 1 h, 34.2 +/- 6.1; and 6 h, 23.4 +/- 4.7 ng/kg/min; NS). We did observe a circadian variation in AII reactivity. Whether the increase in cardiovascular responsiveness to NA after administration of insulin contributes to the elevation in blood pressure frequently observed in patients with insulin resistance remains to be proven.
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PMID:Exogenous insulin augments in healthy volunteers the cardiovascular reactivity to noradrenaline but not to angiotensin II. 186 61

The aims of this study were to determine whether chronic hyperinsulinemia, comparable to that found in obese hypertensives, elevates mean arterial pressure (MAP) or potentiates the hypertensive effects of angiotensin II (ANG II). Studies were conducted in conscious dogs with kidney mass reduced by 70% in order to increase their susceptibility to hypertensive stimuli. Insulin infusion (0.5 or 1.0 mU.kg-1.min-1 iv) for 7 days with plasma glucose held constant raised plasma insulin more than fivefold but did not increase MAP in four dogs on 138 meq/day Na intake. In seven dogs maintained on a high Na intake (319 meq/day), insulin infusion (1.0 mU.kg-1.min-1) for 28 days raised fasting insulin from 9.8 +/- 1.5 to 56-78 microU/ml but did not increase MAP, which averaged 106 +/- 2 mmHg during control and 102 +/- 2 mmHg during 28 days of insulin infusion. Insulin caused transient sodium and potassium retention followed by renal "escape" that was associated with increased glomerular filtration rate (12-27%). Plasma renin activity and plasma aldosterone were not altered by insulin. In five dogs infused with ANG II (2.0 ng.kg-1.min-1) to cause mild hypertension, insulin infusion (1.0 mU.kg-1.min-1) for 6-28 days did not increase MAP further. Thus chronic hyperinsulinemia did not elevate MAP, even when kidney mass was reduced, and did not potentiate the hypertensive effects of ANG II. These findings suggest that additional factors besides hyperinsulinemia per se are responsible for obesity-associated hypertension.
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PMID:Chronic hyperinsulinemia and blood pressure regulation. 218 Mar 21

The aim of this study was to determine whether chronic hyperinsulinemia, comparable to that found in obesity-associated hypertension, causes sustained increases in mean arterial pressure (MAP) or potentiates the hypertensive effects of angiotensin II (ANG II). Insulin infusion (0.5 or 1.0 mU/kg/min, IV), with plasma glucose held constant by IV glucose infusion, for seven to 28 days raised plasma insulin by five- to ten-fold, but did not significantly change MAP in dogs with reduced kidney mass that were maintained on high sodium intake. In dogs infused with ANG II to cause mild hypertension, insulin for 28 days did not potentiate the hypertension. Insulin infusion did, however, cause modest sodium retention during the first few days of infusion. These findings suggest that additional factors besides hyperinsulinemia per se are responsible for obesity-associated hypertension.
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PMID:Does chronic hyperinsulinemia cause hypertension? 292 97

To determine the impact of the renin-angiotensin-aldosterone system on left ventricular function and structure, 36 untreated patients with essential hypertension (WHO class I and II) were examined. Posterior wall thickness, relative wall thickness, and left ventricular mass were determined by M-mode echocardiography. Plasma renin activity, aldosterone, angiotensin I, and angiotensin II levels were measured by radioimmunoassay. Plasma renin activity was related to 24-hour urinary sodium excretion. Of all the endocrine parameters, only the angiotensin II level correlated with posterior wall thickness (r = 0.50, p less than 0.05) and relative wall thickness (r = 0.46, p less than 0.05). This relationship was confirmed by stepwise multiple regression analysis taking arterial pressure, obesity, and sodium excretion into account (p less than 0.05). Plasma renin activity but not the angiotensin II level correlated positively with the ejection fraction (r = 0.42, p less than 0.05) and velocity of circumferential fiber shortening (r = 0.57, p less than 0.01). Thus, angiotensin II emerged as a determinant of left ventricular structural adaptation in essential hypertension.
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PMID:Does the renin-angiotensin-aldosterone system modify cardiac structure and function in essential hypertension? 297 63

The relationships of obesity, glucose metabolism and hormonal variables to mean arterial pressure (MAP) regional vascular resistance and signs of structural vascular changes, were determined in 70 men aged 49 years with normal to mildly elevated MAP randomly selected from a population sample. Regional vascular resistances and signs of structural vascular changes were measured in the calf by plethysmography at rest and during maximal dilatation, and in the kidneys by renal blood flow determination during graded subpressor doses of angiotensin II. MAP was positively correlated to body fat, waist circumference, fat cell size, and to blood glucose 60 minutes after an oral load. This supports an association between central obesity, impairment of glucose tolerance and hypertension. MAP was, however, unrelated to sodium intake, blood volume and indices of sympathetic nervous activity and the renin-angiotensin system. Resting vascular resistance in the calf was unrelated to MAP, while renal vascular resistance rose significantly with increasing MAP. Signs of structural change were significantly correlated to MAP in both these vascular areas. These signs were also associated with central obesity of the hypertrophic type and with impairment of glucose tolerance, even when the association to MAP was accounted for. These factors may be involved in the pathogenesis of the structural adaptation of resistance vessels as hypertension develops.
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PMID:The relationship between obesity-related metabolic factors and vascular changes in early hypertension. 350 95


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