Chapter 22 An adenosine A3 receptor-selective agonist does not modulate calcium-activated potassium currents in hippocampal CA1 pyramidal neurons

Abstract

This chapter presents the effects of a selective A 3 agonist, 2 - chloro - N6 - (3 - iodobenzyl)-adenosine - 5' - N - methyluronamide (Cl-IB-MECA), are characterized on hippocampal CA 1 pyramidal neurons. The chapter examines the possibility that activation of A 3 receptors could lead to activation of protein kinase A (PKA), protein kinase C (PKC), or calcium/calmodulin dependent protein kinase II (CaM-K), which might then induce significant changes in the activity of hippocampal pyramidal neurons. CA1 pyramidal neurons were recorded in the whole cell mode using patch electrodes, and the effects of adenosine agonists were determined on the holding current, and on the amplitude of the slow outward calcium-activated K + currents activated following a depolarizing step in the command voltage Z (I AHP ). The result discussed in the chapter suggest that either A 3 receptors are not present on the cell bodies of hippocampal CA1 pyramidal neurons; that they are present but not linked to PKA, PKC, or CaM-K activation; or that they only activate these kinases in cell compartments that are not accessible to the ion channels that underlie the AHP response.