Scheufler K, Opitz H
Biomed Biochim Acta. 1986;45(5):637-47.
Myocardial contractility of the rabbit ventricle, expressed as contractility index KI = d log (p - p0)/dtmax, was altered by both aortic nerve reflex stimulation and by beta-receptor blockade with propranolol (Obsidan) and talinolol (Cordanum, (+)-Cordanum and (-)-Cordanum). In every case, beta-receptor blockade decreased negative reflex inotropy, whereas reflex hypotension was only reduced by Obsidan. The mean reflex inotropy was 11.8% after Obsidan application and 17.3% after Cordanum injection, the reflex hypotension 28.0% and 34.8%. From the results it is concluded that Cordanum acts in the rabbit ventricle cardioselectively. If neural and pharmacological effects are related to initial effects, we may conclude that the contractile state maintained by the resting sympathetic tone is diminished. The overall reduction of KI by Cordanum blockade and reflex inhibition amounts to 45.5%, that of blood pressure to 42%. Its optical isomers act also cardioselectively, the inotropic effects, however, are smaller than those of the racemate. Obviously, reflex stimulation and beta 1-blocking agents have a similar mode of inotropic action. From this we suggest that reflex inotropy is mediated by sympathetic nerve fibres and beta 1-adrenergic receptors.
以收缩性指数KI = d log (p - p0)/dtmax表示的兔心室心肌收缩性，可通过主动脉神经反射刺激以及用普萘洛尔（心得安）和他林洛尔（可坦宁、(+)-可坦宁和(-)-可坦宁）进行β受体阻滞来改变。在每种情况下，β受体阻滞都会降低负性反射性变力作用，而反射性低血压仅被心得安降低。应用心得安后平均反射性变力作用为11.8%，注射可坦宁后为17.3%，反射性低血压分别为28.0%和34.8%。从结果可以得出结论，可坦宁在兔心室中具有心脏选择性作用。如果神经和药理作用与初始作用相关，我们可以得出结论，静息交感神经张力维持的收缩状态会减弱。可坦宁阻滞和反射抑制导致的KI总体降低达45.5%，血压降低达42%。其光学异构体也具有心脏选择性作用，然而，变力作用比消旋体小。显然，反射刺激和β1阻滞剂具有相似的变力作用方式。由此我们认为，反射性变力作用是由交感神经纤维和β1肾上腺素能受体介导的。
