哌唑嗪在不同实验模型上的抗心律失常作用

用不同的心律失常模型来研究α受体阻断药哌唑嗪的作用,结果表明,哌唑嗪对氯仿,氯化钡,乌头碱,毒毛花甙G及冠状动脉结扎-再灌注所引起的室性心律失常均有抗心律失常作用,预先用普蔡洛尔本身并不产生抗心律失常的作用,也不影响哌唑嗪的抗心律失常作用,但用普蔡洛尔反而使乌头碱及氯化钡诱发大鼠室性心律失常更为明显,提示α受体阻断药是通过多种机理产生抗心律失常作用的。

Antiarrhythmic effects of prazosin on several experimental models

The coexistance of a andβ-adrenergic receptors in mammalian heart was well demonstrated in several studies.This paper presented the antiarrhythmic effects of prazosin(Pra),an a adrenoceptor blocker,in several arrhythmogenic animal models.The results showed that Pra(0.7 mg·kg-1,ip)reduced the incidence of chloroform-induced ventricular fibrillation(VF)from 16/19 to 5/20 and delayed the onset time of respiratory arrest from 85±s14 s to 117±s 15 s(P<0.01)in mice.The occurrences of arrhythmia caused by BaCl2 and by coronary ligation-reperfusion in rats were 10/10 and 6/6 respectively and Pra(0.5 mg·kg-1,ip)decreased it by 3/10 and 3/6,respectively.In the experiments with aconitine in rats or strophantin G in guinea pigs,the treatment with Pra(0.5 mg·kg-1)revealed that the doses of either aconitine or strophantin G,by which ventricular tachycardia(VT)or VF occurred,were increased(from 12.8±s 2.4 and 6.4±s 1.9μg to 17.0±s 3.6 and 9.4±s 1.5μ increase the densities of α-adrenoceptors in ventricular myocardium of the rats.In order to evaluate the effect of α-adrenoceptors in arrhythmia,we pretreated with Pro in all animals except those in chloroform-and reperfusion-induced arrhythmia.Pro at a dose of 2 mg·kg-1·d-1×7 d had no antiarrhythmic effects itself.However,before 30 min of experiments beginning,pretreatment with Pro in the same dose did not influence on the onset of arrhythmia in control groups and the antiarrhythmic effects of Pra.But in control groups Pro did reduce the threshold of aconitine to induce VT and did prolongthe time course of VT caused by BaCl2.It can be concluded that: 1.Pra,an α1-adreno-ceptor blocker,exerts an antiarrhythmic effects in all kinds of arrhythmogenic animal models; 2.Pro which does not reveal an antiarrhythmic effect can promote the onset of arrhythmias in some experimental models,such as BaCl2 and aconitine models; 3.the antiarrhythmic effects of Pra might not contribute only to its α1-adrenoceptor blocking.The antiarrhythmic mechanisms of Pra remain to be further investigated.