CELLULAR MODULATION OF MICROVESSEL PERMEABILITY IN VIVO

  • He, Ping (PI)
  • HE, PINGNIAN (PI)
  • HE, PINGNIAN (PI)

Project: Research project

Project Details

Description

The overall aim of this project is to investigate the cellular
mechanisms involved in permeability modulation in intact microvessels.
The propose studies have two specific aims. Under Specific Aim 1, the
hypotheses to be tested are that (1) increased endothelial [Ca2+]I
triggered nitric oxide (NO) release is a necessary step for increasing
microvessel permeability under inflammatory conditions; and (2) basal
levels of NO release provide an oxidant scavenger function to maintain
the integrity of microvessels under control conditions. In addition to
its role as a vasodilator, NO has been recognized as an important
intrinsic modulator of microvessel permeability. Further investigation
of the roles of NO in modulating microvessel permeability under
different conditions is of great significance. In the proposed studies,
the NO-dependent signal transduction pathway in endothelial cells will
be modified and, changes, in endothelial [Ca2+]I and microvessel
permeability will be determined under the same experimental conditions.
To further investigate mechanisms of NO besides the activation of
guanylate cyclase in regulating permeability, investigator has developed
a method to detect he changes in oxidant levels from cells forming the
microvessel wall using a fluorogenic probe after NO suppression. The
unique advantages of the approach are that all of the experiments will
be conducted in intact microvessels, which have normal permeability
properties, and that the single microvessel perfusion technique will
enable the direct effect of NO on changes in permeability to be
separated from its hemodynamic effect as a vasodilator. Under Specific
Aim 2, the hypotheses to be tested are that the increases in endothelial
[Ca2+]I associated with leukocyte migration are similar to those
elicited by inflammatory mediators, and leukocyte migration can be
reduced by attenuating calcium influx and increasing the barrier
function of endothelial cells. The investigator has developed a novel
method to delineate endothelial boundaries with silver precipitation in
vivo, which provides a mapping tool for the study of calcium signaling
in individual endothelial cells in intact microvessels. The use of
confocal microscopy will enable local changes in microvessel
permeability and individual endothelial [Ca2=]I to be measured and the
vascular structure to be identified in vivo simultaneously. These are
the most director experimental approaches to investigating the
relationship between changes in endothelial cell [Ca2+]I, leukocyte
migration, and local changes in vascular permeability on an individual-
cell basis. This degree of cellular localization in intact microvessels
could not be achieved by previous methods.
StatusFinished
Effective start/end date12/1/965/14/16

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