[Possible role of sarcoplasmatic reticulum in anti-arrhythmic effects of the class III agent amiodarone].

The study was designed to evaluate changes in functional activity of cardiomyocyte sarcoplasmic reticulum under effect of amiodarone (1 mM). It was shown that post-rest potentiation significantly increased after perfusion of cardiomyocytes with amiodarone or calcium (3 mM). The stimulatory action of amiodarone was more pronounced than that of calcium. Treatment with amiodarone solution containing high concentration of calcium had a lower potentiating effect compared with that of perfusion with either of them. Moreover, amiodarone in combination with calcium significantly extended the period of relaxation without affecting the contraction rate. It is concluded that amiodarone improves activity of sarcoplasmic reticulum.