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Oxidative phosphorylation in the rat arterial smooth muscle


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Peng, Zhancong 1996 , 'Oxidative phosphorylation in the rat arterial smooth muscle', Research Master thesis, University of Tasmania.

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Morphological, stereological, biochemical and physiological
techniques were used to investigate the smooth muscle oxidative
phosphorylation activity of the rat arteries, particularly small arteries with a
diameter about 500 µm. The major object of the research was the rat tail
Morphological and stereological analysis found that the differences
between the elastic arteries, muscular arteries and arteriole were mainly in the
contents of smooth muscle. In the rat thoracic aorta, the smooth muscle
volume fraction was 43.7±3.7% of the vessel wall. The proportion of the
smooth muscle layers to the elastic lamella of this artery was about 1: 1. The
rat femoral and tail arteries had smooth muscle contents of 82.5±3.1 % and
79.3±1.3%. The proportions of the smooth muscle layers to the elastic lamella
of these two arteries were 5-11:1 and 6-14:1. The smooth muscle in the
arteriole was 57.2±3.1 % with very little elastic tissue.
The mitochondrial volume fractions in the arterial vascular smooth
muscle cells of the aorta, arterioles, tail and femoral arteries were 6.9±0.8%,
7.8±1.0%, 8.4±0.7% and 7.8±0.7%. The mean value of the mitochondrial
volume fraction for all arteries studied was 7.7%. All blood vessels had a
similar range of mitochondrial volume fraction.
Regardless of the arterial class, the mitochondrial volume fraction
appears to account for approximately 8% of the volume of the arterial smooth
muscle cells of all arteries chosen in the rat. On the basis of that value, the
mitochondrial contents for the entire arterial walls for the aorta, tail and
femoral arteries were 3.5%, 6.3% and 6.6%.
The cytochrome c oxidase activities of the arteries and cardiac muscle
were measured biochemically and found to be 3.8±0.38 µmol.min-1.g-1 and
9.6±0.50 µmol.min-1.g-1 for the aorta and tail artery, and 93.8±19.3
µmol.min-1.g-1 for the cardiac muscle respectively. Because the
mitochondrial contents of the aorta, tail artery and cardiac muscle were 3.5%,
6.3% and 29%, the cytochrome c oxidase activities for the smooth muscle
mitochondria of aorta and tail artery are 108 µmol.min-1.g-1 and 152
µmol.min-1.g-1, with 324 µmol.min-1.g-1 for the mitochondria of the cardiac
muscle. This gives the calculated cytochrome c oxidase activities of the rat
aorta and the tail artery as approximately 240 µmol.h-1.g-1 and 600 µmol.h1.g-1
The physiological oxidative phosphorylation capacity was measured by
the perfusion of isolated rat tail arteries. Under air oxygen tension, the basal
oxygen consumption was 103.1±6.8 µmol.h-1.g-1at37°C. The uncoupler 2-4
dinitrophenal (DNP) induced increase of oxygen uptake was 143.0±16.9
µmol.h-1.g-1. The total oxygen uptake after the infusion of DNP was
247.1±12.7 µmol.h-1.g-1. This suggests that the physiological oxidative
capacity may be about 40% of the theoretical oxidative capacity in a rat tail
artery. Tail artery perfusions oxygenated with 95% oxygen gave higher values
of oxygen consumption although these measurements were necessarily less

Item Type: Thesis - Research Master
Authors/Creators:Peng, Zhancong
Keywords: Mitochondria, Vascular smooth muscle, Rats, Arteries, Tissue respiration, Oxygen
Copyright Holders: The Author
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Thesis (M.Med.Sc.)--University of Tasmania, 1996. Includes bibliographical references (leaves 176-199).

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