Table 3

Ryanodine receptor modulation: Functional classification

Ca2+ReleaseγPoKD Examples
Class Iincreased or decreased3-a decreasedincreasedryanodine
Class IIincreasedunchangedincreased3-b decreasedCa2+ caffeine, MBED, sulmazole, doxorubicin adenine nucleotides, suramin
Class IIIincreasedunchanged different from class IIhalothane, heparin, bastadins
Class IVdecreasedunchangeddecreased3-c increasedMg2+, ruthenium red,  aminoglycosides, FLA 365
Class Vdecreasedunchanged different from class IVprocaine, tetracaine phenylalkylamines dantrolene
Class VIdecreaseddecreasedunchangedvariablespermine, QX 314
Class VII— — — — — — — delayed persistent channel inactivation3-d— — — — — —  doxorubicin, ruthenium red,  neomycin
  • 3-a Ryanodine has a double effect in release experiments, as detailed in the text.

  • 3-b Due to decreased lifetime of the closed channel and/or increased lifetime of the open channel.

  • 3-c Due to increased lifetime of the closed channel and/or decreased lifetime of the open channel.

  • 3-d This action is produced after prolonged incubation with several agents whose immediate effect belongs to a different class.

  • γ, channel conductance; KD , [3H]ryanodine dissociation constant.