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

Cerebral blood flow, electrical activity, and neurological function were studied in rabbits subjected to either 15 minutes of oligemia (20 torr cerebral perfusion pressure) or complete cerebral ischemia produced by cisterna magna infusion. During oligemia, flow was reduced from 68.4 +/- 4.2 ml/100 gm/min to 26.3 +/- 4.4 (p less than .01), and during ischemia animals had no proven flow. By 5 minutes after oligemia or ischemia significant symmetrical hyperemia occurred and there was no evidence of the no-reflow phenomenon. The electroencephalogram became isoelectric significantly later and returned significantly sooner in oligemia than in ischemia. Oligemic animals had earlier and better return of neurological function than their ischemic counterparts, although postinsult hypocapnia improved functional recovery in both groups. These experiments do not support the concept that oligemia is a more severe insult than complete ischemia. In intracranial hypertension produced by this model, the no-reflow phenomenon does not occur.
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PMID:Experimental cerebral oligemia and ischemia produced by intracranial hypertension. Part 1: Pathophysiology, electroencephalography, cerebral blood flow, blood-brain barrier, and neurological function. 115 66

The authors studied the effect on cortical metabolites of intracranial hypertension produced by the infusion of mock cerebrospinal fluid into the cisterna magna in rabbits subjected to 15 minutes of cerebral oligemia (20 torr) or 15 minutes of complete ischemia. In both groups high-energy metabolites were exhausted within the first 5 minutes of the 15-minute insult. Significant recovery of the high-energy intermediates occurred within 15 minutes of reperfusion, well before return of electroencephalogram (EEG) activity. Continued reperfusion, during which electrical activity and function were returning, brought only moderate improvement in energy metabolites. In contrast, severe lactic acidosis persisted at least 15 minutes after insult, but was reduced by the time EEG activity returned. At no time were there striking differences in metabolites between the oligemic and ischemic groups. These results indicate that recovery in general, and the significantly earlier recovery of oligemic as compared to ischemic animals, cannot be explained on the basis of energy supply. Whether the persistence of lactic acidosis is an important factor limiting return of function requires further study.
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PMID:Experimental cerebral oligemia and ischemia produced by intracranial hypertension. Part 3: Brain energy metabolism. 115 68

Regional cerebral blood flow (rCBF) was measured after intracarotid injection of 133Xe concurrently with measurements of local cerebral blood flow (LCBF) after injection of 133Xe directly into the distal stump of the occluded middle cerebral artery (MCA) by the use of the gamma camera after producing experimental ischemia in baboons by occluding the MCA. Regional MCA stump pressure (rMCAP) was also measured. Regions of ischemia assessed by intracarotid injection of 133Xe correlated well with the territory of infarct defined by injection of 133Xe into the distal MCA stump. Flow values in ischemic regions obtained by direct injection of 133Xe into the MCA were 15% to 20% lower than those obtained by intracarotid injection of 133Xe. Possible explanations for these differences are discussed. During induced hypertension autoregulation in ischemic areas was abolished and paradoxical responses of LCBF and rMCAP to changes in arterial carbon dioxide tension (PaCO2) were confirmed.
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PMID:Regional cerebral blood flow measured by the gamma camera after direct injection of 133Xe into the distal stump of the occluded middle cerebral artery. 115 74

The effect of changes in orthostatic pressure on vascular resistance in subcutaneous adipose tissue was examined in the forearm at normal tension and in the leg at local orthostatic hypertension in three normal subjects. Blood flow in subcutaneous tissue was measured by the local xenon-133 washout technique. Changes in orthostatic pressure were achieved by postural changes of the extremity. At levels above the heart where venous pressure is constant, there was autoregulation of blood flow over a wider arterial blood pressure range in leg than in forearm. When transmural pressure increased 25 mm Hg or more vascular resistance increased about 50 per cent in the dependent forearm and 300 per cent in the dependent leg. The effect of ischemia on vascular resistance was investigated in cutaneous tissue of hand and foot by means of the 131I-Antipyrine initial slope technique. Vascular resistance after maximum dilatation achieved after 20, 30, and 35 min of ischemia was less in vessels of the hand than in vessels of the foot. Thus, adaptive structural changes of vessels subjected to increased blood pressure are present in cutaneous and subcutaneous adipose tissues in normal subjects.
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PMID:Vascular resistance in peripheral blood vessels at normotension and at local orthostatic hypertension in healty humans. 121 Dec 2

The role of rat adrenal mineralocorticoid function in the development of experimental reno-vascular hypertension was studied. Na-retention action of aldosterone was blocked by means of verospiron. Daily excretion of aldosterone proved to be significantly increased in rats with unilateral stenosis of the renal artery (the contralateral kidney was intact). In ischemia of the only kidney there was seen no change in the activation of adrenal mineralocorticoid function. Administration of verospiron strongly suppressed the development of the first form of reno-vascular hypertension and had no effect on the blood pressure in rats with stenosis of the only kidney.
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PMID:[Role of aldosterone in the initial stage of 2 forms of experimental vasorenal hypertension]. 122 11

Placental blood-flow rates in rabbits were measured by the indirect method of local apparent conductivity. In our experiments, hypertension was produced by injection or infusion of hypertensive drugs. As a result of hypertension we observed a marked decrease in placental blood flow. Vasoconstriction seems to be the pathophysiologic mechanism causing the reduced blood flow rate. Accordingly, the placenta may not be considered as a "priviledged organ" in circulatory regulations. In our experiments, placental ischemia subsequently to ligatures did not produce hypertension so that the production of a placental pressor-substance could not be demonstrated. If we assume a circulus vitiosus hypertension-placental ischemia-hypertension, the hypertension seems to be the primary cause.
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PMID:[Studies on placental blood flow under drug induced hypertension (animal experiments) (author's transl)]. 124 31

Transversal epidemiologic investigations carried out in different populations from several regions of Romania : Gurghiu Valley (lumberjacks from a mountain region), Danube Delta and Razelm lagoon complex (fishermen), and Bucharest have shown that, in spite of the high caloric value of food and even of a high intake of saturated fats, mean serum cholesterol is lower in the rural areas than in Bucharest, probably owing to the strenuous physical work. However, except myocardial infarction, more frequent in the urban than in the rural regions, the other forms of coronary heart disease have a relatively higher frequency in villages, particularly atrial fibrillation and ECG signs of ischemia. These findings might be explained by a greater prevalence of hypertension in these populations. It is concluded that the risk factors, which act synergically, depend on the complex structure of the "ecologic niche".
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PMID:Coronary heart disease and risk factors in some special type collectivities. 124 94

The management of 23 patients with traumatic pseudoaneurysms is presented. A pulsatile mass associated with pain was the usual presentation. Hypertension and hypovolemic shock from rupture are uncommon presentations but potential hazards of this lesion. Twenty-one pseudoaaeurysms were treated surgically. Resection with end-to-end anastomosis (eight patients), with graft replacement (one patient), with lateral repair (seven patients) was done. Hypothermia with circulatory arrest and external Dacron shunt were used to prevent visceral ischemia during high aortic occlusion. There were no mortalities or significant postoperative complications.
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PMID:Traumatic pseudoaneurysms: a review of 32 cases. 124 98

Superimposition of an adrenal scan on a renal scan revealed a kidney defect not appreciated on the renal scan alone. The defect proved to be ischemia of the upper pole of the kidney. Resection of the lesion alleviated the patient's hypertension.
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PMID:Combination of renal and adrenal scanning in the diagnosis of renovascular hypertension: case report. 126 42

Atherosclerosis and insufficiency of the coronary arteries and their sequelae are summarized in the term "coronary heart disease". For the evaluation of the coronary arteries the knowledge of malformations, variants and supply areas is of importance. Extension and severity of atherosclerosis of the coronary arteries and their insufficiency is being influenced by hyperlipidemia, hypertension and diabetes mellitus. The process of atherosclerosis as a cause of the proliferation of vascular smooth muscle cells in complicated by ulceration, parietal and obliterative thrombosis as well by intramural hemorrhages. Relative ischemia leeds to disseminated cell necrosis; total ischemia causes large myocardial tissue necrosis, called infarction. Localization and extension of infarction and the later scars correspond to the caliber of the obliterated coronary artery and to the significance of the collaterals. Postmortem coronary angiography can detect cause and extension of the damaged cardiac area. Functional significance of chronic coronary heart disease is related to the "critical connective tissue content" of the heart. After surgical treatment qualitative and quantitative morphology may help to explain postoperative cardiac failure.
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PMID:[Morphology of coronary heart disease (author's transl)]. 126 48


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