Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present single-blind, randomised, cross-over, placebo-controlled study was set up to compare the first-dose effects upon blood pressure (BP) and cerebral blood flow (CBF, measured by Xenon inhalation) of a single oral dose of atenolol 50 mg and enalapril 5 mg in ten hypertensive patients receiving a thiazide diuretic. It was found that a) the timing and degree of fall in BP after the first dose of atenolol and enalapril on a diuretic background were similar and generally not associated with symptoms or a fall in CBF, and b) dizziness, which is sometimes associated with the first-dose effect of ACE inhibitors in hypertensives on diuretics, can occasionally occur accompanied by a substantial fall (43%) in CBF in the absence of marked falls in systolic blood pressure. It is suggested that the latter event may be linked to a disturbance of cerebral autoregulation in part dependent on localised renin-angiotensin systems.
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PMID:First-dose effects of enalapril and atenolol upon blood pressure and cerebral blood flow in patients with mild hypertension on diuretic therapy. 219 32

Regional cerebral blood flow was measured with the 133-Xenon inhalation method in seven healthy subjects with orthostatic hypotension not due to autonomic failure (i.e. non-neurogenic clinical disorder). Measurements were performed during supine rest and during head-up tilt (70 degrees). All subjects had a consistent drop in systolic blood pressure and the typical symptomatology of orthostatic hypotension. The results showed lower mean hemispheric blood flow during head-up tilt than during supine rest. In addition, a consistent and significant redistribution of the regional flow values was seen, with a reduction in frontal and an increase in postcentral areas. The frontal flow decrease during tilt was more marked than in subjects without orthostatic hypotension and was not related to variations in the level of PCO2 or to respiration. In contrast to the clinical symptoms of orthostatic hypotension (dizziness, nausea, visual disturbances, and in some cases syncope), the cortical blood flow reduction was, however, relatively moderate.
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PMID:Cortical blood flow during head-up postural change in subjects with orthostatic hypotension. 812 63