Figure 6.
Phosphatase 1 appears to be the major phosphatase dephosphorylating CaMKII in cardiomyocytes. Pacing triggers autophosphorylation of CaMKII only when phosphatase 1 (and 2a) is inhibited, but not when phosphatase 2b (calcineurin) or 2a alone are inhibited. Phosphatase inhibitors used were cypermethrin (1 μM; 30 min preincubation), okadaic acid (200 nM; 30 min precincubation) and calyculin A (1 μM; 10 min precincubation). Phosphatase 2b was also inhibited by cyclosporin A, phosphatase 2a by cantharidin and phosphatase 1 by higher concentrations of OA yielding the same result (data not shown).