Protein kinase C has recently been shown to modulate the slow recovery from inactivation of Na+ channels in apical dendrites of hippocampal CA1 pyramidal neurons. Moreover, dendritic, A-type K+ channels have been found to be modulated by protein kinases A and C and by mitogen-activated protein kinase. The electrical signalling ability of these dendrites is thus highly regulated by a number of neurotransmitters and second-messenger systems.