ALPHA-SUBUNIT OF CALCIUM-CALMODULIN DEPENDENT PROTEIN-KINASE ENHANCESEXCITATORY AMINO-ACID AND SYNAPTIC RESPONSES OF RAT SPINAL DORSAL HORN NEURONS

1. Here we report that in acutely isolated rat spinal dorsal horn (DH) neurons, the lpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate and N-methyl-D-aspartate (NMDA) receptors can be regula ted by endogenous and exogenous calcium/calmodulin-dependent protein k inase II (CaM-KII). Intracellularly applied, the alpha-subunit of CaM- KII enhanced AMPA/kainate and NMDA currents recorded with the use of t he whole cell patch-clamp technique. 2. Microcystin, a nonselective ph osphatases inhibitor, also enhances AMPA and NMDA responses. 3. Conven tional intracellular recordings were made from substantia gelatinosa n eurons in spinal cord slices to determine the effect of intracellular application of CaM-KII on excitatory synaptic potentials evoked by ele ctrical stimulation of primary afferent fibers. Excitatory synaptic tr ansmission was enhanced by CaM-KII, which is consistent with the impor tance of phosphorylation of the postsynaptic AMPA/kainate and NMDA rec eptor-ion complexes in the short- and long-term changes in synaptic tr ansmission.