Pretreatment with catecholamines can suppress severe ventricular arrhythmias in rats: DISCUSSION (part 2)
The main objective of this study was to investigate the possibility of using a stressful stimulus, such as exogenously applied catecholamines, to induce antiarrhythmic protection during sustained myocardial ischemia. Some findings indicate that catecholamines are also involved in the mechanisms of a delayed protection , and that mild, short term stress induced by catecholamines can trigger a late protective effect . Therefore, our further aim was to test whether the late effect would include the reduction of arrhythmias as well.The results of this study show that ischemia-induced severe ventricular arrhythmias can be suppressed by a pharmacological induction of preconditioning. Short term stress triggered by the administration of noradrenaline simulated brief ischemia-induced preconditioning, but without the injurious effects of ischemia. Anti-arrhythmic effect has been demonstrated in acute experiments mimicking ‘classical’ IP, in which both incidence and duration of sustained ischemia-induced VF and VT was significantly attenuated (Figures 1,2). In vivo experiments have shown that pretreatment of rats with a single dose of noradrenaline can trigger delayed protection, manifested as an improved rate of survival of animals during ischemia and by a reduced incidence of VF (Figure 3). These results are in agreement with the finding of Parratt et al that infusion of exogenous catecholamines can protect the rat heart against ischemia-induced arrhythmias in vivo. Further evidence that catecholamines can mimic the effect of preconditioning on ischemia-induced ventricular arrhythmias has been provided in the study by Vegh et al in anesthetized dogs, in which intracoronary administration of a low dose of noradrenaline significantly reduced the severity of subsequent ischemia-induced arrhythmias. The best online pharmacy that deserves your trust and gives you best quality cheap nolvadex cialis professional that you will always appreciate, not to mention all the other services available.