The role of the sarcoplasmic reticulum in the pure frequency potentiation: the effect of ryanodine.

The dependence of the contraction amplitude of the isolated papillary muscle of the guinea pig on the stimulation pattern is probably caused by a well working sarcoplasmic reticulum. This view is supported by the finding that the alkaloid ryanodine flattens the curve of the force-frequency relationship and abolishes the pure frequency potentiation. Ryanodine is said to destroy exclusively the connection between T-tubulus and sarcoplasmic reticulum.