Akademik Veri Yönetim Sistemi
Archivos espanoles de urologia, cilt.51, sa.7, ss.739-40, 1998 (Scopus)
INTRACAVERNOSAL ENDOTHELIN LEVELS OF
IMPOTENT MEN BEFORE AND AFTER PAPAVERINE
INDUCED PENILE ERECTION
ABSTRACT------ Objectives:Endothelin
and nitric oxide (NO) are modulating factors of vascular tonus.Recent data have
given support to the assumption that penile erection is the consequence of
competition of vasodilator NO and vasoconstrictor endothelin on penis. Reported
that atherosclerotic vascular disease is presented with increased endothelin and
decreased NO release, this study was designed to search for a similar
endothelin alteration in corpus
cavernosum of penis.
Methods:Intracavernosal
endothelin levels of 33 impotent men with
arteriogenic impotence before and after papaverine induced penile erection were
examined by using radio-immunoassay kits.
Results:The
intracavernosal endothelin levels of arteriogenic impotent men in our study were
not altered both in flaccid and papaverine induced erectile state.
Conclusions:The
lack of alteration was concluded to be the possible result of cavernosal damage
in arteriogenic impotence leading to diminished release of NO and increased
release of endothelin.
KEY WORDS------ Impotence, endothelin, penile erection.
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A)INTRODUCTION:
The vascular tone is modulated by overall actions of vasodilator or
vasoconstrictor humoral factors released by vascular endothelium.Endothelin , a
21-residue peptide and one of the known most potent vasoconstrictors, is a
modulating factor which has long been proposed to play an important role in
penile erectile function(1).Such diverse experimental findings as expression of
endothelin mRNA in cultured endothelial cells from the human corpus cavernosum
(2), contractile effect of endothelin on isolated corpus cavernosum (1),
inhibitory action of nitric oxide synthase inhibitors (i.e. L-NOARG) on the
erectile response (3) and enhancement of endothelin mediated vasoconstriction
by endothelium-derived relaxing factor (EDRF) or nitric oxide (NO) (4) have
given rise to the popular assumption that the resultant penile erection induced
by any kind of stimuli (reflexogenic, psychogenic, nocturnal) is at least partially
the consequence of competition of vasodilator NO and vasoconstrictor endothelin
on the target organ-penis.The present study was designed to further investigate
the intracavernosal kinetics of endothelin and find further support that
endothelin ,as a vasoconstrictor agent, plays a crucial role in the
pathophysiology of arteriogenic impotence.
B)MATERIALS
AND METHODS: 33 patients with mild to severe
arteriogenic impotence were evaluated by standardized, routine methods as
detailed history of physical examinations, duplex sonography of penile arteries
and dynamic cavernosography.Two blood samples of 2 ml. was obtained from each
patient by puncture of corpus cavernosum before and 2 minutes after
intracavernosal injection of 60 mg. papaverine.The age of patients ranged from
21 to 68 years.Most patients(70%) were between 40 and 70 years old.Blood
samples were collected in heparine solution and all samples were examined by
radio-immunoassay kits.The statistical significance of difference between
intracavernosal levels of endothelin in the flaccid state and erection were
evaluated by Student's t-test.
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C)RESULTS
AND DISCUSSION: Intracavernosal endothelin levels of
impotent men ranged from 0.12 to 1.30
pg/ml in the flaccid state while they
ranged from 0.13 to 1.69 pg/ml during papaverine induced erection.The mean
values during flaccid state and erection were 0.68 ± 0.26 pg/ml and 0.69 ± 0.34
pg/ml respectively.The intracavernosal endothelin levels of arteriogenic impotent
men in our study were not altered both
in flaccid and papaverine induced erectile state.
Diminished NO release by atherosclerotic
vessels and increased plasma endothelin concentration in atherosclerotic
vascular disease have been previously reported(4).Our study revealed no significant
difference between the intracavernosal levels of men with impotence of
arteriogenic origin in both flaccid and erectile state, as we expected.The lack
of alteration between the flaccid and erectile state in our trial may be a
dubious consequence of participating cavernosal damage leading to diminished
release of NO (which reverses the constrictor actions of endothelin), increased
release of endothelin and subsequently arteriogenic impotence.Therefore, further
trials demonstrating the intracavernosal
endothelin levels in flaccid state and erection in both potent and impotent men
of any origin (arteriogenic, venogenic, neurogenic, psychogenic) are
recommended to test this hypothesis and better characterize the intracavernosal
kinetics of endothelin in the
pathogenesis of erectile disfunction.
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REFERENCES:
1.Holmquist F, Andersson K-E and Hedlund H.Actions of
endothelin on isolated corpus cavernosum from rabbit and man. Acta Physiol
Scand 139,113,1990.
2.Saenz de Tejada I, Carson MP, Traish A et al.Role of
endothelin, a novel vasoconstrictor peptide, in the local control of penile
smooth muscle.J Urol 141, 222A,1989.
3.Holmquist F, Stief CG, Jonas U et al.Effects of the nitric
oxide synthase inhibitor NG-nitro-L-arginine on the erectile response to
cavernous nerve stimulation in the rabbit.Acta Physiol Scand 143,299,1991.
4.Lerman A, Sandok
EK, Hildebrand FL et al.Inhibition of endothelium-derived relaxing factor
enhances endothelin-mediated vasoconstriction.Circulation 85(5),1894,1992.