Effect of hypothyroidism on the nitrergic relaxant responses of corpus cavernosal smooth muscle in rabbits.
BACKGROUND
The incidence of hormonal dysfunction as a cause of impotence remains controversial. However, several recent studies have reported evidence of hormonal abnormalities in 25-35% of impotent men. Hypothyroidism has been reported to occur in 6% of impotent men.


METHODS
In the present study, we examined nitrergic responses in hypothyroidism in rabbit corpus cavernosum and compared them with controls.


RESULTS
Carbachol-induced relaxation responses and electrical field stimulation (EFS)-induced frequency-dependent relaxations decreased significantly in hypothyroid rabbits. Papaverine and sodium nitroprusside (SNP)-induced relaxation responses did not change significantly in hypothyroid rabbits. The contraction responses of phenylephrine and EFS-induced frequency-dependent contractions were significantly decreased in the hypothyroid group.


CONCLUSIONS
We can speculate that the reduction of relaxant responses to EFS and carbachol in hypothyroid rabbits can depend on a decreased release of nitric oxide (NO) from nitrergic nerves and endothelium or a reduction of muscarinic receptor density. Also, decreases in contraction responses may depend on diminished adrenoceptor density.
Sarac
Bulent
B
Department of Pharmacology, School of Medicine, Cumhuriyet University, Silvas, Turkey.
Yildirim
Mustafa K
MK
Bagcivan
Ihsan
I
Kaya
Kemal
K
Kilicarslan
Hakan
H
Yildirim
Sahin
S
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D004195:Disease Models, Animal; D004558:Electric Stimulation; D007037:Hypothyroidism / Q000150:complications / Q000503:physiopathology*; D018783:Impotence, Vasculogenic / Q000209:etiology / Q000503:physiopathology; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology*; D009599:Nitroprusside / Q000494:pharmacology*; D010208:Papaverine / Q000494:pharmacology; D010413:Penis / Q000187:drug effects / Q000503:physiopathology*; D011817:Rabbits; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*
D018679:Cholinergic Agonists; D014665:Vasodilator Agents; D009599:Nitroprusside; D002217:Carbachol; D010208:Papaverine