Changes in microvascular hematocrit during post-occlusive reactive hyperemia: descriptions and mechanisms
Year: 2015
Type: dissertation
Abstract: The primary aim of this dissertation was to describe the changes in microvascular hematocrit, as total[hemoglobin+myoglobin] (T[Hb+Mb] measured with near-infrared spectroscopy (NIRS), during post-occlusive reactive hyperemia (PORH).Mechanisms of reactive hyperemia within skeletal muscle were also explored.The investigation detailed in Chapter 2 of this dissertation found that the differing time courses of the kinetic responses of both oxy-and deoxy [Hb+Mb], are related to changes in T [Hb+Mb].We also determined that adipose tissue thickness had no effect on a purely temporal analysis of NIRS data.In Chapter 3 we observed that brachial artery reactive hyperemia preceded changes in T[Hb+Mb] during reactive hyperemia.Assuming that myoglobin remained constant, we posited that changes in T[Hb+Mb] must reflect alterations in red blood cell concentration in the microvasculature, i.e., microvascular hematocrit.In Chapter 4 comparisons were made between brachial artery blood flow, cutaneous and skeletal muscle flux and T [Hb+Mb].The conduit artery response was faster than the microvascular responses in all tissues.Within skeletal muscle, time to peak and the time constant for the on-kinetics were faster in T[Hb+Mb] compoared with intramuscular flux as measured with intramuscular laser-Doppler.We observed no differences in temporal responses between cutaneous and intramuscular measures and suggested that in a purely temporal analysis the cutaneous microvasculature could serve as an analog for the skeletal muscle microvasculature.Finally, in Chapter 5 we found that prostaglandin inhibition with ibuprofen altered the initial T[Hb+Mb] response during PORH without impacting cutaneous flux or brachial artery blood flow.Chapter 5 also discussed that the addition of a wrist cuff to our standard instrumentation prevented the accumulation of T[Hb+Mb] during the occlusion period.
Author: Christopher M. Bopp
Language: English
Subfield: Hematology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2279535976