The nonaddrenergic noncholinergic (NANC)neurotransmission in urinary bladder of the rats.

• Main Authors: Ying-Cho Hung, 洪英哲
• Other Authors: Juei-Tang Cheng
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/45646597920437839481

碩士 === 國立成功大學 === 藥理學研究所 === 84 === It is well known that the rat urinary bladder possesses an non- adrenergic, non-cholinergic ( NANC) innervation. However, the neurotransmitter for this NANC neurotransmission is still contro- versial and is the main interest of our research.The rat detrusor muscle strips were studied in organ bath in vitro and contraction were induced by electric-field stimulation (EFS). The amplitude of contraction increased as the frequency was increased.The frequency-dependent contractions were almost completely abolished by tetrodotoxin (TTX), indicating that the response to EFS was predominantly neurogenic. The NANC contraction was obtained in the presence of the four autonomic nerve blockers (atropine, guanethidine, phentolamine and propranolol). The NANC component constituted a greater portion of the contraction at low frequency than that at high frequency. Desensitization induced by a.b-MeATP , a P2x receptor agonist, reduced the NANC contractions evoked by a constant stimulating frequency 3Hz (EF50).Meanwhile, this NANC response was abolished mostly in ATP desensitized sample. Adenosi -ne has a similar activity asATP. In addition, this NANCcontrac -tion was also abolished mostly by P2 receptor blockers suramin and P2x receptor blocker PPADS, at concentrations sufficient to block a.b-MeATP-induced contraction. It is suggested that this NANC contraction in urinary bladder might be one of the pur- inergic actions of ATP. Dipyridamole, a adenosine uptake inhibitor ,inhibited NANC contraction at concentrations which influenced the action of a, b-MeATP. DPCPX, a A1 adenosine receptor blocker, did not affect NANC contraction even at high concentration. The adenyl purines released by EFS from nerve were detected by HPLC and the amount of ATP was more than adenosine.Therefore,combining measurement of adenyl purines release and the results of fun- ctional studies,the present study suggests that ATP plays an important role in NANC neurotransmission of the rat bladder.