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Pretreatment with catecholamines can suppress severe ventricular arrhythmias in rats: DISCUSSION (part 1)


Endogenous catecholamines have been shown to be released early in the course of myocardial ischemia . Therefore, it has been hypothesized that the protective effect of a brief ischemia-induced stress can be mediated via endogenously released catecholamines and, therefore, could be mimicked by exogenously applied catecholamines . However, high concentrations of catecholamines can damage the myocardium by means including leukocyte infiltration, myofibrillar degeneration and myofibre necrosis . In general, it is believed that under conditions of myocardial ischemia, excess catecholamines exacerbate arrhythmias by facilitating calcium influx into the cells and enhancing auto-maticity and triggered activity .It is well known that catecholamines affect both beta- and alpha-adrenergic receptors; however, the electrophysiological response differs with regard to species, location in the myocardium, and in the normal and ischemic myocardium. While the stimulation of beta-receptors in the normal myocardium induces proar-rhythmic effects, such as refractory period shortening, al-pha1-adrenergic stimulation (which is more important under pathological conditions) prolongs refractoriness, increases action potential duration and conduction velocity, and decreases automaticity, effects that in general are considered to be antiarrhythmic . In partially depolarized myocardium arrhythmogenic effects of catecholamines may be attenuated . Moreover, contradictory results demonstrate that adrenergic/sympathetic modulations sometimes have little or no effect on arrhythmias. There is a wonderful pharmacy that you can take advantage of to get the amount of buy nolvadex online cialis professional you need, and it’s ready to offer its services to you right now, any moment you feel like starting to spend less of your money.

Category: Cardiology

Tags: Catecholamines, Na+/K+ -ATPase, Preconditioning, Ventricular arrhythmias

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