The heart and microvasculature have characteristics of a complex adaptive
system. Extreme challenges faced by these organ systems cause structural changes
which lead to global adaptation. To assess the impact of myocardial interstitial edema on
the mechanical properties of the left ventricle and the myocardial interstitium, we
induced acute and chronic interstitial edema in dogs. With chronic edema, the primary
form of collagen changed from type I to III and left ventricular chamber compliance
significantly increased. The resulting functional adaptation allows the chronically
edematous heart to maintain left ventricular chamber compliance when challenged with
acute edema, thus, preserving cardiac function over a wide range of interstitial fluid
pressures.
To asses the effect of microvascular occlusions, we reintroduced the Pallid bat
wing model and developed a novel mathematical model. We hypothesized that
microvessels can switch from predominantly pressure-mediated to shear-mediated
responses to ensure dilation during occlusions. Arterioles of unanesthetized Pallid bats
were temporarily occluded upstream (n=8) and parallel (n=4) to vessels of interest (20-65 mm). In both cases, the vessels of interest rapidly dilated (36+24 %, 37+33 %),
illustrating that they responded appropriately to either decreased pressure or increased
shear stress. The model not only reproduced this switching behavior, but reveals its
origin as the nonlinear shear-pressure-radius relationship.
The properties of the heart and microvasculature were extended to characterize a
“Research-Intensive Community” (RIC) model, to provide a feasible solution consistent
with the Boyer Commission, to create a sustainable physiology research program. We
developed and implemented the model with the aim of aligning diverse goals of
participants while simultaneously optimizing research productivity. While the model
radically increases the number of undergraduate students supported by a single faculty
member, the inherent resilience and scalability of this complex adaptive system enables
it to expand without formal institutionalization.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2658 |
| Date | 15 May 2009 |
| Creators | Desai, Ketaki Vimalchandra |
| Contributors | Quick, Christopher M. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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