Pretreatment with catecholamines can suppress severe ventricular arrhythmias in rats: Relevance to ischemic preconditioning (part 1)
Severe ventricular arrhythmias present a major challenge for therapeutic intervention due to complexity of pathophysiological mechanisms initiating arrhythmias in ischemic heart disease. Moreover, many antiarrhythmic drugs are known to share proarrhythmic properties. Hence, the development of a new approach to management of arrhythmias is urgently needed.During the past decade a new concept of myocardial protection against ischemia based on exploitation of endogenous protective mechanisms of the heart, termed ischemic preconditioning (IP), has been introduced . Apart from ‘classical’ short term preconditioning, a delayed protection known as the ‘second window of protection’ and triggered by the same stressful stimulus has been demonstrated in different experimental models .Protection afforded by IP includes reduction in cell necrosis and in life-threatening arrhythmias , and is believed to be mediated by the mechanisms of cell signalling, which opens the possibilities for the pharmacological modulation at different levels of the signal transduction (receptors, second messengers, effectors). A number of substances, both protective and deleterious, are known to be released in the myocardium during early ischemia and to modulate arrhythmogenesis . Some of these potentially protective substances (eg, adenosine) have been implicated as mediators of IP . Moreover, stimulation of the A1 receptors by selective adenosine analogues has been found not only to be capable of inducing an IP-like effect, but also to afford a delayed protection against infarction . However, this does not seem to be a universal mechanism of protection because in the rat heart IP has not been found to be mediated by adenosine . Furthermore, it does not account for the anti-arrhythmic effect of IP in the canine model. Shop online with the best pharmacy that will ensure high quality of your medications and will offer cheapest Generic Cialis Professional with no rx required any time you need this or any other one for your medical problem.