Effect of hypothyroidism on the purinergic responses of corpus cavernosal smooth muscle in rabbits.
OBJECTIVE
Several studies have reported evidence of hormonal abnormalities in 25-35% of impotent men. Hypothyroidism has been reported to occur in 6% of impotent men. In the present study, we examined purinergic relaxation responses in hypothyroidism in an experimental rabbit model and compared them with controls to evaluate the possible involvement of the purinergic pathway.


METHODS
The study comprised 20 male New Zealand white rabbits. The rabbits were divided into two equal groups. We tested the effects of ATP, alpha beta ATP, and adenosine precontracted with phenylephrine on the isolated corpus cavernosum preparations from control and hypothyroid rabbits. We also evaluated the effects of ATP, alpha beta ATP, and adenosine on the cGMP levels in the isolated corpus cavernosum preparations from control and hypothyroid rabbits.


RESULTS
T3, T4, and testosterone levels were significantly lower in hypothyroid rabbits. ATP, alpha beta ATP, carbachol, and electrical field stimulation (EFS)-induced frequency-dependent relaxation responses in the isolated rabbit corpus cavernosum strips precontracted with phenylephrine reduced significantly (P<0.05). Adenosine-induced relaxation responses did not change significantly in hypothyroid rabbits.


CONCLUSIONS
Reduction of relaxation response in hypothyroid rabbits corpus cavernosum can depend on a decreased release of nitric oxide (NO) from nitrergic nerves and endothelium.
Yildirim
M K
MK
Department of Pharmacology, School of Medicine, Cumhuriyet University, Sivas, Turkey.
Bagcivan
I
I
Sarac
B
B
Kilicarslan
H
H
Yildirim
S
S
Kaya
T
T
D000241:Adenosine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism; D004195:Disease Models, Animal; D004558:Electric Stimulation; D005260:Female; D007037:Hypothyroidism / Q000150:complications* / Q000378:metabolism*; D018783:Impotence, Vasculogenic / Q000209:etiology* / Q000378:metabolism; D008297:Male; D009126:Muscle Relaxation / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000502:physiology; D010413:Penis / Q000378:metabolism*; D011983:Receptors, Purinergic / Q000502:physiology*; D013739:Testosterone / Q000378:metabolism; D013963:Thyroid Hormones / Q000378:metabolism; D013965:Thyroidectomy
D011983:Receptors, Purinergic; D013963:Thyroid Hormones; D013739:Testosterone; D000255:Adenosine Triphosphate; D006152:Cyclic GMP; D000241:Adenosine