| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Microcirculation Laboratory, Department of Bioengineering and The Whitaker Institute of Biomedical Engineering, University of California San Diego, La Jolla, California
Submitted 14 July 2004 ; accepted in final form 28 September 2004
One mechanism for organ damage in individuals with arterial hypertension may be due to oxygen free radical production. This study was designed to localize free radicals in a microvascular network of mature spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats. Because glucocorticoids play a role in pressure elevation of SHRs, we investigated their role in microvascular free radical formation. Oxygen radical production in mesentery was detected by tetranitroblue tetrazolium reduction to formazan aided by digital light-absorption measurements. Formazan deposits were observed in the endothelial cells and lumens of all microvessels and in lymphatic endothelia but were fewer in tissue parenchyma. The formazan distribution in younger (14–16 wk old) WKY rats and SHRs was heterogeneous with low values in capillaries and small arterioles/venules (<30 µm) but enhanced deposits in larger venules. Adrenalectomy served to reduce the formazan density in SHRs to the level of WKY rats, whereas dexamethasone supplementation of the adrenalectomized rats caused elevation in the larger venules of SHRs. In older (40 wk old) SHRs, formazan levels were elevated in all hierarchies of microvessels. After pressure reduction was employed with chronic hydralazine treatment, the formazan deposits were reduced in all locations of the microcirculation in both WKY rats and SHRs. Elevated formazan deposits were also found in lymphatic endothelium. These results suggest that oxygen free radical production is elevated in both high- and low-pressure regions of SHR microcirculation via a process that is controlled by glucocorticoids. Older SHRs have higher formazan levels than younger SHRs in all microvessels. Chronic hydralazine treatment, which serves to reduce arterial blood pressure, attenuates tetranitroblue tetrazolium reduction in WKY rats and SHRs even in venules of the microcirculation, which has no micropressure elevation. Free radical production may be a more global condition in SHRs and may not be limited to arteries and arterioles.
mesentery; arteriole; capillary; venule; superoxide; nitroblue tetrazolium; dexamethasone; Wistar-Kyoto; adrenalectomy; hydralazine
This article has been cited by other articles:
|
|
 |
|
  A Izzotti, S C Sacca, A Bagnis, and S M Recupero Glaucoma and Helicobacter pylori infection: correlations and controversies Br J Ophthalmol, November 1, 2009; 93(11): 1420 - 1427. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. A. DeLano and G. W. Schmid-Schonbein Proteinase Activity and Receptor Cleavage: Mechanism for Insulin Resistance in the Spontaneously Hypertensive Rat Hypertension, August 1, 2008; 52(2): 415 - 423. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y.-X. Shi, Y. Chen, Y.-Z. Zhu, G.-Y. Huang, P. K. Moore, S.-H. Huang, T. Yao, and Y.-C. Zhu Chronic sodium hydrosulfide treatment decreases medial thickening of intramyocardial coronary arterioles, interstitial fibrosis, and ROS production in spontaneously hypertensive rats Am J Physiol Heart Circ Physiol, October 1, 2007; 293(4): H2093 - H2100. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Feletou and P. M. Vanhoutte Endothelial dysfunction: a multifaceted disorder (The Wiggers Award Lecture) Am J Physiol Heart Circ Physiol, September 1, 2006; 291(3): H985 - H1002. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. E. Lau, J. J. Galligan, D. L. Kreulen, and G. D. Fink Activation of ETB receptors increases superoxide levels in sympathetic ganglia in vivo Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2006; 290(1): R90 - R95. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
