Role of shear stress on nitrite and NOS protein content in different size conduit arteries of swine.
OBJECTIVE
Inherent fundamental difference exists among arteries of different sizes. The purpose of this study was to evaluate the relation between regional difference of wall shear stress (WSS) in various sizes arteries and contents of nitrite and NO synthase (NOS) isoforms.


METHODS
Five different conduit arteries in a wide range of diameter (1-8 mm) were examined in the hind limbs of 13 pigs. Blood flow rate and outer diameter were measured in vivo to determine WSS. Arterial tissues were harvested for the measurement of nitrite and NOS protein contents. The concentration of nitrite, a product of NO synthesis, was determined by high-performance liquid chromatography method. Western blot analysis was used to assess the protein contents of endothelial NOS (eNOS), inducible NOS (iNOS) and neuronal NOS (nNOS).


RESULTS
Our data show that WSS increases with a decrease in artery diameter. Nitrite level increases with increasing WSS and hence decreases with artery diameter. The eNOS protein contents decrease with an increase in diameter. No significant difference for iNOS and nNOS protein contents was found with different artery diameter. A significant positive correlation between tissue nitrite and eNOS protein contents was also observed. Finally, the WSS-normalized eNOS is not significantly different in various size vessels.


CONCLUSIONS
Regional difference in blood flow has no effect on iNOS and nNOS protein contents in these conduit arteries. Regional difference in eNOS expression and nitrite contents may be related to the WSS-induced NO by the endothelium under normal physiological conditions.
Department of Biomedical Engineering, Surgery, and Cellular and Integrative Physiology, IUPUI, Indianapolis, IN, USA.
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D000818:Animals; D001158:Arteries / Q000033:anatomy & histology / Q000502:physiology*; D001160:Arterioles / Q000033:anatomy & histology / Q000502:physiology; D001783:Blood Flow Velocity; D005260:Female; D008297:Male; D019001:Nitric Oxide Synthase / Q000145:classification / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D009929:Organ Size; D020033:Protein Isoforms; D033081:Shear Strength / Q000502:physiology*; D013314:Stress, Mechanical; D013552:Swine
D009573:Nitrites; D020033:Protein Isoforms; D019001:Nitric Oxide Synthase