7-氯苄基四氢帕马丁及奎尼丁对豚鼠离体心房及大鼠血管环的作用比较

7-氯苄基四氢帕马丁( 7-Cl-BTHP)及奎尼丁(Qui)均能明显延长豚鼠离体左心房的功能性不应期，显著抑制肾上腺素诱发的自律性，但7-Cl-BTHP能明显增强豚鼠离体左心房的收缩力，而Qui则对其无影响. 在心脏肥厚大鼠及正常大鼠的离体主动脉环，7-Cl-BTHP及Qui对去甲肾上腺素所致的收缩均有抑制作用. 7-Cl-BTHP的 IC₅₀分别为76及39 μmol·L^-1，而Qui的IC₅₀则分别为4.6及8 μmol·L^-1. Qui对氯化钾所致心脏肥厚及正常大鼠主动脉环的收缩有明显的抑制作用，其pD₂′分别为4.3及4.0，而7-Cl-BTHP则对其无影响. 结果提示7-Cl-BTHP的抗心律失常作用可能与延长不应期，降低自律性和抗α受体作用有关.

Comparison of effects of 7-chloro-benzyltetrahydropalmatine and quinidine on isolated left atria of guinea pigs and aortic ring of rats

7-Chloro-benzyltetrahydropalmatine (7-Cl-BTHP) 30 μmol·L^-1 and quinidine 30 μmol·L^-1 markedly prolongated functional refractory period(FRP) from (109±4) ms to (134±9) ms and from (109±6) ms to (140±8) ms, respectively and significantly inhibited epinephrine induced automaticity on left atria of guinea pig. In contrast，contractility of guinea pig left atria was markedly increased by 7-Cl-BTHP， but was not influenced by quinidine. Blocking effects of 7-Cl- BTHP and quinidine on α-adrenoreceptor were also investigated in normal and cardiac hypertrophy rat aortic rings.Both of 7-Cl-BTHP and quinidine reduced contraction induced by norepinephrine in concentration-dependent manner，the IC₅₀ (76 μmol·L^-1 for cardiac hypertrophy and 39 μmol·L^-1 for normal) of 7-Cl-BTHP were much higher than those (4.6 μmol·L^-1 for cardiac hypertrophy and 8 μmol·L^-1 for normal rats) of quinidine. The concentration-response to KCl was non-competitively inhibited by quinidine in normal and cardiac hypertrophy rat aortic ring. The pD₂′ values were 4.0 and 4.3 respectively， but 7-Cl-BTHP was unable to shift the KCl concentration- respone curves， indicating that it had no influence on potential dependent calcium channel. The results indicate that antiarrhythmic action of 7-Cl-BTHP are related to prolong refractory period，decrease automaticity and block α-adrenoreceptor.