Chaotic behavior of the coronary circulation |
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Authors: | Jerome Trzeciakowski William M Chilian |
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Institution: | (1) Department of Systems Biology and Translational Medicine, Texas A&M Health Science Center College of Medicine, College Station, TX, USA;(2) Department of Integrative Medical Sciences, Northeastern Ohio Universities College of Medicine, 4209 State Route 44, PO Box 95, Rootstown, OH 44272-0095, USA |
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Abstract: | The regulation of the coronary circulation is a complex paradigm in which many inputs that influence vasomotor tone have to
be integrated to provide the coronary vasomotor adjustments to cardiac metabolism and to perfusion pressure. We hypothesized
that the integration of many disparate signals that influence membrane potential of smooth muscle cells, calcium sensitivity
of contractile filaments, receptor trafficking result in complex non-linear characteristics of coronary vasomotion. To test
this hypothesis, we measured an index of vasomotion, flowmotion, the periodic fluctuations of flow that reflect dynamic changes
in resistances in the microcirculation. Flowmotion was continuously measured in periods ranging from 15 to 40 min under baseline
conditions, during antagonism of NO synthesis, and during combined purinergic and NOS antagonism in the beating heart of anesthetized
open-chest dogs. Flowmotion was measured in arterioles ranging from 80 to 135 μm in diameter. The signals from the flowmotion
measurements were used to derive quantitative indices of non-linear behavior: power spectra, chaotic attractors, correlation
dimensions, and the sum of the Lyapunov exponents (Kolmogorov–Sinai entropy), which reflects the total chaos and unpredictability
of flowmotion. Under basal conditions, the coronary circulation demonstrated chaotic non-linear behavior with a power spectra
showing three principal frequencies in flowmotion. Blockade of nitric oxide synthase or antagonism of purinergic receptors
did not affect the correlation dimensions, but significantly increased the Kolmogorov–Sinai entropy, altered the power spectra
of flowmotion, and changed the nature of the chaotic attractor. These changes are consistent with the view that certain endogenous
controls, nitric oxide and various purines (AMP, ADP, ATP, adenosine) make the coronary circulation more predictable, and
that blockade of these controls makes the control of flow less predictable and more chaotic.
Supported by NIH grant HL32788. |
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Keywords: | Coronary circulation Coronary microcirculation Chaos Modeling Nitric oxide |
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