Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.11.1.7 (peroxidase)
 65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acute arterial hypertension was induced in male Wistar rats using two experimental techniques: (1) i.v. injection of Aramine and (2) infusion of physiological saline as a bolus via internal carotid artery. Horseradish peroxidase (HRP) was injected i.v. prior to both experimental procedures and subsequently localized in the brain by light and electron microscopy. In the saline infusion (pressure pulse) model, colloidal lanthanum was also applied as a diffusion tracer following fixation of the cerebral endothelium. In the Aramine model, extravsation of HRP correlated with abrupt elevation of blood pressure. In the pressure pulse model HRP extravasation was consistently visualized in the affected hemisphere. Electron microscopy showed consistent labeling of plasmalemmal vesicles by HRP in segments of cerebral endothelium. However, HRP was also clearly visualized in junctional pools suggesting focal opening of endothelial tight junctions as a pathway for extravasation of this tracer in both hypertensive models. Colloidal lanthanum not transported by plasmalemmal vesicles across endothelium after fixation of the brain also bypassed consecutive membrane appositions of endothelial tight junctions indicating existance of interendothelial pathways to macromolecules in acute arterial hypertension.
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PMID:Blood-brain barrier opening to horseradish peroxidase in acute arterial hypertension. 50 90

The effects of acute hypertension and respiratory stress induced by Aramine (metaraminol bitartrate) upon blood-brain barrier (BBB) permeability to horseradish peroxidase (HRP) were studied in adult inbred white rats. The BBB permeability was quantitated by slicing the brain of each animal into 500-mu thick sections, incubating the sections using the Reese-Karnovsky method, and counting all observed HRP perivascular exudates. No evidence of BBB compromise or significant elevation of blood pressure (BP) was observed in the following experimental groups: 1) control group of five animals; 2) hyperventilated group of five animals (final mean arterial blood gases; pO2, 104.2 mm Hg; pCO2, 24.8 mm Hg; pH, 7.53); 3) anoxic-stress group of five animals (final mean arterial blood gases; pO2, 31.4 mm Hg; pCO2, 58.2 mm Hg; pH 7.21). However, in a group of 15 animals subjected to anoxic stress followed by hyperventilation, in addition to extreme changes in the levels of arterial blood gases, a significant BP increase occurred (mean BP increase per second, 3.43 +/- 0.25 mm Hg; final mean BP, 163.3 +/- 3.18 mm Hg); as well as significant BBB opening (mean number of HRP exudates per animal, 12.2 +/- 0.85). Likewise, a final group of 10 animals given intravenous Aramine displayed a significant systemic BP elevation (mean BP increase per second, 6.9 +/- 0.38 mm Hg; final mean BP, 165.8 +/- 3.16 mm Hg), accompanied by BBB opening (mean number of exudates per animal, 51.5 +/- 5.95). The variable most strongly associated with the degree of barrier opening was the rate of BP rise (correlation coefficient = +0.84).
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PMID:Influence of respiratory stress and hypertension upon the blood-brain barrier. 677 41