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Microcirculation. 1994 Dec;1(4):213-30.

Imaging of Ca2+ transients in endothelial cells of single perfused capillaries: correlation of peak [Ca2+]i with sites of macromolecule leakage.

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1
Department of Human Physiology, School of Medicine, University of California, Davis 95616, USA.

Abstract

OBJECTIVE:

To investigate the mechanisms responsible for variation in the macromolecular leakage (formation of localized leaky sites) in venular microvessels with increased permeability, we examined the hypothesis that cytoplasmic calcium concentration [Ca2+]i, does not increase uniformly within microvessel endothelial cells.

METHODS:

We loaded the endothelial cells forming the walls of venular microvessels in frog mesentery with fura-2, and imaged [Ca2+]i using a cooled CCD camera.

RESULTS:

Control [Ca2+]i was close to 60 nM in all regions. Control permeability was uniformly low in all microvessels. Exposure to ionomycin (5 mM) increased [Ca2+]i in a biphasic manner, but not uniformly. There was variation in both time to peak (bimodal distribution) and peak [Ca2+]i (274 +/- 13 nM; mean variation above or below the peak value was 110 nM). Raising extracellular calcium from 1.1 to 5 mM increased the mean variation of [Ca2+]i about peak values. Extravascular leakage of fluorescently labeled albumin or low-density lipoproteins was most prominent at sites where increase in [Ca2+]i were largest.

CONCLUSIONS:

These data indicate that variation in [Ca2+]i within individual endothelial cells or groups of cells could account, at least in part, for the distribution of localized leakage sites for macromolecules in venular microvessels in the high-permeability state.

PMID:
8790591
[Indexed for MEDLINE]

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