CA2+ CALMODULIN KINASE-II TRANSLOCATES IN A HIPPOCAMPAL SLICE MODEL OF ISCHEMIA/

Rat hippocampal slices were exposed to conditions that simulate an isc hemic insult, and the subcellular distribution and the enzymatic activ ity of Ca2+/calmodulin-dependent protein kinase II (CaM kinase) were m onitored. Semiquantitative western blots using a monoclonal antibody t o the 50-kDa a subunit showed that there was a significant redistribut ion of the enzyme from a supernatant to a pellet fraction after 10 min of an anoxic/ aglycemic insult. No significant change in the total am ount of CaM kinase enzyme was detected in the homogenates for up to 20 min of exposure to the insult. Ca2+/CaM-dependent enzyme activity did not significantly change in the pellet during the 20-min insult. Supe rnatant activity decreased throughout the insult. The persistence of C a2+/CaM-dependent CaM kinase activity in the pellet fraction and the d etected movement of enzyme from the supernatant to the pellet indicate that redistribution may be an important mechanism in regulating the c ellular location of CaM kinase activity.