de Freitas J C, Sawaya M I
Biosciences Institute, University of São Paulo, Brazil.
Toxicon. 1990;28(9):1029-37. doi: 10.1016/0041-0101(90)90141-s.
The effects of caissarone (C8H11N5O) on guinea-pig ileum and rat duodenum preparations are reported. Caissarone evoked, at first, a small response, as compared with that of applied acetylcholine. This effect was blocked by atropine, hexamethonium and slightly reduced by tetrodotoxin. The main caissarone effect seems to be on the myenteric plexus as it increased spontaneous activity, tone and peristalsis; these effects being counteracted by tetrodotoxin, hexamethonium and atropine. Extracellular electrophysiological recording of the action potentials of myenteric plexus neurons showed an increase in frequency in the presence of caissarone. Caissarone potentiated the longitudinal muscle tension responses elicited by transmural electric stimulation in both control conditions, and when tension was reduced by pretreatment with tetrodotoxin or adenosine triphosphate. Caissarone also potentiated the longitudinal muscle tension responses to applied acetylcholine and this effect was reduced, but not abolished, by tetrodotoxin. Caissarone may have an indirect excitatory action on nicotinic receptors at the ganglia or may act as a reversible antagonist of purine transmitters released by neurons of the myenteric plexus involved in the physiological inhibition of intestinal motility.
本文报道了凯萨罗宁（C8H11N5O）对豚鼠回肠和大鼠十二指肠标本的作用。与应用乙酰胆碱相比，凯萨罗宁起初引起的反应较小。这种效应被阿托品、六甲铵阻断，被河豚毒素轻微减弱。凯萨罗宁的主要作用似乎在于肌间神经丛，因为它增加了自发活动、张力和蠕动；这些效应被河豚毒素、六甲铵和阿托品抵消。对肌间神经丛神经元动作电位的细胞外电生理记录显示，在有凯萨罗宁存在时频率增加。在对照条件下以及在用河豚毒素或三磷酸腺苷预处理使张力降低时，凯萨罗宁均增强了经壁电刺激引起的纵肌张力反应。凯萨罗宁还增强了对应用乙酰胆碱的纵肌张力反应，且这种效应被河豚毒素减弱但未消除。凯萨罗宁可能对神经节的烟碱受体有间接兴奋作用，或者可能作为由参与肠道运动生理抑制的肌间神经丛神经元释放的嘌呤递质的可逆拮抗剂起作用。
