Journal of Andrology, Vol. 25, No. 3, May/June 2004
Copyright © American Society of Andrology
Effect of Chronic Ischemia on Constitutive and Inducible Nitric Oxide Synthase Expression in Erectile Tissue
KAZEM M. AZADZOI*,
,
TARA A. MASTER* AND
MIKE B. SIROKY*,
From the * Boston University School of Medicine
and the
Veterans Affairs Boston Healthcare
System, Boston, Massachusetts.
|
Correspondence to: Dr Kazem Azadzoi, Urology Research (151), Boston VA Medical
Center, 150 S Huntington Ave, Boston, MA 02130 (e-mail:
kazadzoi{at}bu.edu). |
Arterial occlusive disease is one of the leading causes of organic erectile
dysfunction (ED). Recent studies have shown that the incidence of
cardiovascular disease closely correlates with the prevalence of ED. Also, ED
is thought to be an early signal of impending cardiovascular problems. We
previously found that the atherosclerosis of iliohypogastric arteries in the
rabbit causes ED, down-regulates cavernosal neuronal nitric oxide synthase
(nNOS) gene expression, and impairs NO synthesis. The goal of this study was
to determine the effect of atherosclerosis-induced ischemia on cavernosal
nNOS, endothelial NOS (eNOS), and inducible NOS (iNOS) expression and
NO-mediated smooth muscle relaxation in the rabbit. Our study showed that
iliac artery blood flow, intracavernosal blood flow, and intracavernosal
oxygen tension were unchanged 4 weeks after the induction of arterial
atherosclerosis, whereas they were significantly diminished at weeks 8 and 16.
Erectile responses to nerve stimulation and cavernosal smooth muscle
relaxation were unchanged at week 4 and were significantly diminished at weeks
8 and 16 after the induction of atherosclerosis. Western blotting showed that
cavernosal nNOS and eNOS protein levels were unaffected at week 4 but were
significantly decreased at weeks 8 and 16 after the induction of
atherosclerosis. iNOS protein, however, markedly increased during the course
of the induced arterial disease. Immunohistochemical staining showed no change
in cavernosal eNOS or nNOS expression at week 4. A dramatic decrease in both
was evident at 8 and 16 weeks. iNOS expression progressively increased between
4 and 16 weeks of atherosclerosis. Down-regulation of nNOS and eNOS, along
with up-regulation of iNOS, may explain ischemic cavernosal smooth muscle
relaxation impairment in the rabbit. Ischemically altered NOS expression may
be of great pathophysiologic importance in atherosclerosis-induced ED. These
data may provide further insight into the mechanism of arteriogenic ED.
Key words: Erectile dysfunction, atherosclerosis, blood flow, oxygen tension
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[Abstract]
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Copyright © 2004 by The American Society of Andrology.