Document Type
Thesis
Date of Award
8-31-1986
Degree Name
Master of Science in Biomedical Engineering - (M.S.)
Department
Biomedical Engineering Committee
First Advisor
David S. Kristol
Second Advisor
Arthur B. Ritter
Third Advisor
Basil Baltzis
Abstract
Microvascular flow velocities and transport of macromolecules were studied in the hamster cheek pouch under control and acute high arterial pressure conditions, with or without topical (local) application of the vasodilating agent, bradykinin. Mean arterial pressures of 130-160% control were attained by intravenous renin infusion. The microcirculation of the cheek pouch was studied using intravital microscopy. Areas with arterioles and venules were recorded on a videotape for later analysis of red cell velocity, using an RBC tracking correlator, and vessel diameter using a video shearing monitor.
In addition, vascular permeability to macromolecules was studied in the hamster cheek pouch vascular bed. Fluorescein-conjugated dextrans of 150,000 daltons molecular weight (FITC Dx 150) were injected intravenously as a macromolecular tracer. The net transport of macromolecules across the vascular wall of the superfused tissue was quantitated by analyzing the clearance of FITC-Dx 150 from the plasma.
From the experiments it was found that the diameters of both arterioles and venules had no significant change under acute high arterial pressure. However, the velocities increased in both the arterioles and venules. Topical application of bradykinin, with or without renin infusion, dilated arterioles and postcapillary venules, and increased the flow velocities in all segments. The vessels dilated to a less extent when bradykinin was topically applied during constant renin infusion, compared to topical application of bradykinin alone. Flow velocities in the vessels were higher following the topical application of bradykinin with renin infusion, compared to just renin infusion or just topical application of bradykinin.
There was no significant change in volumetric flowrates in all vessels, during the acute high pressure alone. In the period following the topical application of bradykinin the flowrates increased significantly in all segments except the large venules (20-30 lam). During the period of acute high pressure following the topical application of bradykinin the flowrates increased significantly in all vessels except large venules (20-30 µm).
Clearance of FITC-Dx 150 increased significantly following the period of topical application of bradykinin with or without elevation of mean arterial pressure. The effects of high arterial pressure and topical application of bradykinin were found to be cumulative on the clearance of FITC-Dx 150 from the plasma.
It is reasonable to conclude that an increased hydrostatic pressure at the postcapillary level contributed to leakage of macromolecules during the acute high pressure period. In addition to the typical permeability enhancement and vasodilation effect of topical application of bradykinin, the effect of acute high pressure with bradykinin further enhanced the leakage of macromolecules.
Recommended Citation
Gawdi, Govind Mohanlal, "The effect of systemic arterial pressure on microvascular flow and transcapillary exchange of macromolecules in the hamster cheek pouc" (1986). Theses. 3398.
https://digitalcommons.njit.edu/theses/3398
