Hypertension, Vol 3, 586-595, Copyright © 1981 by American Heart Association
RA Majack and RC Bhalla
This study examined characteristics of paracellular and pinocytotic
permeability pathways across the middle cerebral artery endothelium of 12-
to 16- month-old spontaneously hypertensive rats (SHR). Interendothelial
junctions in SHR, like those of age-matched Wistar- Kyoto controls, were
impermeable to lanthanum and horseradish peroxidase (HRP) tracers.
Freeze-fracture preparations revealed that interendothelial junctions of
chronically hypertensive rats are characterized by a twofold increase over
controls in the number of tight junctional strands and the mean
apical-basal depth. It is believed that this tight junctional hypertrophy
may function to increase adhesive forces between neighboring endothelial
cells, and may play a role inthe prevention of hypertension-induced
paracellular permeability increases. Morphological and tracer studies of
pinocytotic pathways indicated that, it the middle cerebral artery,
endothelial vesicular transport activity is not increased during chronic
hypertension. No evidence was found to indicate the presence of
transendothelial permeability channels across control or hypertensive
arterial endothelium. Thus, increased transendothelial permeability,
commonly observed in acute hypertension, does not appear to occur during
chronic hypertension, at least in the middle cerebral artery. Our findings
suggest that the arterial endothelium may undergo structural (tight
junctional) adaptation in response to prolonged hypertension.
ARTICLES
Ultrastructural characteristics of endothelial permeability in chronic hypertension
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