RESEARCH

Research interests - Theoretical studies of the microcirculation

The microcirculation is a network of extremely small blood vessels that supplies oxygen and
nutrients to all parts of our tissues. The focus of work in our research group is the use of
mathematical and computational approaches to study blood flow and mass transport in the
microcirculation. Working in collaboration with experimentalists, we aim to understand
quantitatively the processes involved. The main areas of our work are:

Mechanics of blood flow in microvessels. We are examining the relationship between red blood
cell mechanics and flow resistance in microvessels. Theoretical predictions agree well with
observations in glass tubes, but resistance is higher living tissue. We have found that the major
cause is the presence of a relatively thick macromolecular lining (endothelial surface layer) on
the walls of microvessels.

Mass transport to tissue. We are simulating oxygen exchange between networks of microvessels
and surrounding tissues in skeletal muscle and tumors. In skeletal muscle, we have shown
how oxygen can be exchanged diffusively between arterioles and capillaries, and we are studying
the determinants of maximal oxygen consumption. In tumors, we are studying the relationship
between network structure and occurrence of local hypoxic (radiation-resistant) regions. Also,
we are analyzing the delivery of chemotherapeutic drugs in tumor tissues.

Structural adaptation of microvascular networks. We are developing models for the stuctural
responses of microvessels to functional demands. We have found that maintenance of a stable,
functionally adequate distribution of vessel diameters can be achieved if each vessel responds to
changes in wall shear stress, intravascular pressure and local metabolic conditions, and if
mechanisms exist for information transfer upstream and downstream along flow pathways.

Regulation of blood flow: We are developing models for the active regulation of blood flow by
changes in vascular tone, taking into account vascular responses to wall shear stress, pressure and
local metabolic state, and including effects of conducted responses along vessel walls.

For more information, see Microcirculation Division, Arizona Research Laboratories

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Updated 5 December 2000