Ram J L, Judge K, Jednak M A
Department of Physiology, Wayne State University, Detroit, MI 48201, USA.
Comp Biochem Physiol Pharmacol Toxicol Endocrinol. 1994 Feb;107(2):235-42. doi: 10.1016/1367-8280(94)90046-9.
Cholinergic and serotonergic receptors of Aplysia californica buccal muscles were characterized pharmacologically by determining compounds that effectively inhibited contractile responses to acetylcholine (ACh) and modulatory effects of serotonin (5-HT), respectively. pA50 for ACh to elicit contraction averaged 4.7 +/- 0.1 (mean +/- SE, equivalent to 2 x 10(-5) M). Both hexamethonium bromide and atropine inhibited ACh-elicited contractions, but neither inhibited the response completely, nor were the two together able to antagonize the response completely. Curare caused inhibition only at low ACh doses, and muscarinic antagonists pirenzapine and 4-diphenylacetoxy-N-methylpiperidine methiodide caused partial inhibition. The most effective blocker of ACh-elicited contractions was the nicotinic antagonist mecamylamine. 10(-4) M mecamylamine completely blocked the cholinergic response. ACh contractions were inhibited 90% within 10 min and took > 40 min to recover from mecamylamine. Specificity was indicated by the lack of effect of mecamylamine on potassium-elicited contraction. NAN-190 blocked the potentiating effect of 5-HT without having inhibitory or potentiating effects by itself on ACh-elicited contractions. NAN-190 blocked the potentiating effect of 8-OH-DPAT. Cholinergic receptors on Aplysia buccal muscles are most effectively inhibited by mecamylamine and may have mixed nicotinic/muscarinic character. Serotonergic receptors have pharmacological similarities to vertebrate 5-HT1A receptors and may be closely related to the gastropod 5-HTlym receptor.
通过分别确定能有效抑制对乙酰胆碱（ACh）收缩反应的化合物以及5-羟色胺（5-HT）的调节作用，对加州海兔颊肌的胆碱能和5-羟色胺能受体进行了药理学特性研究。ACh引起收缩的pA50平均值为4.7±0.1（平均值±标准误，相当于2×10⁻⁵ M）。溴化六甲铵和阿托品均抑制ACh引起的收缩，但两者均未完全抑制该反应，且两者联合也不能完全拮抗该反应。箭毒仅在低ACh剂量时引起抑制，毒蕈碱拮抗剂哌仑西平和4-二苯基乙酰氧基-N-甲基哌啶甲碘化物引起部分抑制。ACh引起收缩的最有效阻断剂是烟碱拮抗剂美加明。10⁻⁴ M美加明完全阻断胆碱能反应。ACh收缩在10分钟内被抑制90%，从美加明作用下恢复需要超过40分钟。美加明对钾引起的收缩无作用表明了其特异性。NAN-190阻断了5-HT的增强作用，而其自身对ACh引起的收缩无抑制或增强作用。NAN-190阻断了8-羟基-二丙胺基四氢萘（8-OH-DPAT）的增强作用。海兔颊肌上的胆碱能受体最有效地被美加明抑制，可能具有烟碱/毒蕈碱混合特性。5-羟色胺能受体在药理学上与脊椎动物的5-HT1A受体相似，可能与腹足纲动物的5-HTlym受体密切相关。
