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Abstract
Urocortin (UCN), a newly isolated corticotrophin-releasing factor (CRF) related peptide,
has been found to have potent cardiovascular protective effects. This study aimed
to investigate the long-term effects of UCN on arterial remodeling and related functional
alterations. UCN (7 microg/kg/d) was administered to spontaneously hypertensive rats
(SHR) for 8 weeks. Systolic blood pressure (SBP) was measured weekly. Functional studies
were performed on isolated mesenteric arterial segments. Also, by light microscope
and electron microscope, the morphology of mesenteric arteries was examined. Our results
showed that mean SBP in UCN-treated SHRs was about 40 mm Hg lower than that of the
control SHR group, and was similar to that of the enalapril-treated group. In the
mesenteric arterial segments pre-contracted with norepinephrine (0.001-10 microM),
the maximal relaxation rate induced by acetylcholine (10 microM) in UCN-treated group
(about 93.3%) was higher than that in SHR control group (about 40.0%) (n=6, P<0.01).
Furthermore examination under light microscope showed that UCN (3.5 microg/kg/d) treatment
significantly reduced media thickness, media/lumen ratio, resulting in larger lumen
diameter while analysis of transmission electron microscopic findings revealed that
chromatin, internal elastic lamina and densely packed mitochondria displayed a close-to-normal
distribution after UCN treatment. These results suggested that long-term UCN treatment
not only had hypotensive effects but may also inhibited development of vascular remodeling
in mesenteric arteries in SHR.