Effects of plant extract neferine on cyclic adenosine monophosphate and cyclic guanosine monophosphate levels in rabbit corpus cavernosum in vitro.
OBJECTIVE
To further investigate the relaxation mechanism of neferine (Nef), a bis-benzylisoquinoline alkaloid extracted (isolated) from the green seed embryo of Nelumbo nucifera Gaertn in China, on rabbit corpus cavernosum tissue in vitro.


METHODS
The effects of Nef on the concentrations of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in isolated and incubated rabbit corpus cavernosum tissue were recorded using 125I radioimmunoassay.


RESULTS
The basal concentration of cAMP in corpus cavernosum tissue was 5.67 +/- 0.97 pmol/mg. Nef increased the cAMP concentration in a dose-dependent manner (P < 0.05), but this effect was not inhibited by an adenylate cyclase inhibitor (cis-N-[2-phenylcyclopentyl]azacyclotridec-1-en-2-amine, MDL-12, 330A) (P > 0.05). The accumulation of cAMP induced by prostaglandin E1 (PGE1, a stimulator of cAMP production) was also augmented by Nef in a dose-dependent manner (P < 0.05). The basal concentration of cGMP in corpus cavernosum tissue is 0.44 +/- 0.09 pmol/mg. Nef did not affect this concentration of cGMP, either in the presence or in the absence of a guanyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ) (P > 0.05). Also, sodium nitroprusside (SNP, a stimulator of cGMP production)-induced cGMP production was not enhanced by Nef (P > 0.05).


CONCLUSIONS
Nef, with its relaxation mechanism, can enhance the concentration of cAMP in rabbit corpus cavernosum tissue, probably by inhibiting phosphodiesterase activity.
Chen
Jun
J
Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China. jchen121121@hotmail.com
Liu
Ji-Hong
JH
Wang
Tao
T
Xiao
Heng-Jun
HJ
Yin
Chun-Ping
CP
Yang
Jun
J
D000818:Animals; D044182:Benzylisoquinolines / Q000494:pharmacology* / Q000627:therapeutic use; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004365:Drugs, Chinese Herbal; D007172:Erectile Dysfunction / Q000188:drug therapy; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D031653:Nelumbo; D010410:Penile Erection / Q000187:drug effects; D010413:Penis / Q000187:drug effects* / Q000378:metabolism; D008517:Phytotherapy; D010936:Plant Extracts; D011817:Rabbits; D011863:Radioimmunoassay; D012639:Seeds; D014665:Vasodilator Agents / Q000494:pharmacology* / Q000627:therapeutic use
D044182:Benzylisoquinolines; D004365:Drugs, Chinese Herbal; D010936:Plant Extracts; D014665:Vasodilator Agents; C057222:neferine; D000242:Cyclic AMP; D006152:Cyclic GMP