Rattan S, Thatikunta P
Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania.
Gastroenterology. 1993 Sep;105(3):827-36. doi: 10.1016/0016-5085(93)90901-n.
The role of nitric oxide in the gut in response to sympathetic nerve stimulation has not been examined. The present study examined the influence of the NO synthase inhibitor L-NG-nitro-arginine (L-NNA) on responses to hypogastric nerve stimulation (HGNS) in the opossum internal anal sphincter (IAS).
Resting pressures in the IAS (IASP) were monitored using low-compliance continuously perfused catheters.
The predominant response to HGNS was an elevation of the resting tone in the IAS. The other responses of infrequent nature were a decrease in the IASP and a biphasic response (an initial increase followed by a decrease in the IASP). beta-Adrenoceptor antagonist propranolol had no significant effect on the increase in the IASP by HGNS but almost abolished the decrease in the IASP caused by HGNS and unmasked the excitatory responses. The IAS responses to HGNS were frequency dependent and abolished by guanethidine (adrenergic blocker). L-NNA caused significant and stereoselective suppression of all IAS responses to HGNS. The suppressed HGNS responses were completely reversed by the NO precursor L-arginine stereoselectively. The NO synthase inhibitor and guanethidine had no effect on the increase in IASP by phenylephrine.
NO may play a significant role in the facilitatory modulation of sympathetic responses in the IAS.
一氧化氮在肠道中对交感神经刺激的反应作用尚未得到研究。本研究检测了一氧化氮合酶抑制剂L-NG-硝基精氨酸（L-NNA）对负鼠肛门内括约肌（IAS）对腹下神经刺激（HGNS）反应的影响。
使用低顺应性连续灌注导管监测IAS中的静息压力（IASP）。
对HGNS的主要反应是IAS静息张力升高。其他不常见的反应是IASP降低和双相反应（IASP先升高后降低）。β-肾上腺素能受体拮抗剂普萘洛尔对HGNS引起的IASP升高无显著影响，但几乎消除了HGNS引起的IASP降低并揭示了兴奋反应。IAS对HGNS的反应具有频率依赖性，并被胍乙啶（肾上腺素能阻滞剂）消除。L-NNA对IAS对HGNS的所有反应均产生显著且立体选择性的抑制作用。被抑制的HGNS反应被一氧化氮前体L-精氨酸立体选择性地完全逆转。一氧化氮合酶抑制剂和胍乙啶对去氧肾上腺素引起的IASP升高无影响。
一氧化氮可能在IAS交感反应的促进性调节中起重要作用。
