title: ATP-induced membrane currents in ameboid microglia acutely isolated from mouse brain slices.
abstract: Microglial cells were harvested from the surface of corpus callosum slices acutely isolated from the brain of neonatal (five- to seven-day-old) mice. Transmembrane ionic currents were measured employing a standard whole-cell voltage-clamp technique. The extracellular application of 1 mM ATP triggered the generation of a complex membrane current comprising three components: (i) an initial fast inward current which had a reversal potential at about -20 to -15 mV; (ii) this initial component was followed by a steady-state inward current with reversal potential about -50 to -40 mV; and (iii) a delayed inward current with a reversal potential close to 0 mV. The first two components (fast and steady-state) had an activation threshold at 10 microM ATP, and 100 microM ATP evoked an almost maximal response. In contrast, the third component of ATP-induced inward membrane current could be observed only while 1 mM ATP was applied. The increase in concentration of tetra-anionic form of ATP (ATP4-) by removal of divalent cations from the bath solution substantially lowered the activation threshold for the delayed component of ATP-induced membrane current; conversely, lowering the ATP4- concentration (by replacing Ca2+ with Mg2+) resulted in its disappearance. These results suggest that ATP4- acts as a true agonist for the activation of the delayed ATP-induced membrane current. We conclude that microglial cells express several purinoreceptor subtypes. The activation of these receptors might play a role in intracellular signal transduction in brain microglia.
authors.affiliation: Max-Delbrück Center of Molecular Medicine, Berlin-Buch, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Haas
authors.forename: J
authors.initials: J
authors.lastname: Brockhaus
authors.forename: A
authors.initials: A
authors.lastname: Verkhratsky
authors.forename: H
authors.initials: H
authors.lastname: Kettenmann
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000166:cytology / Q000187:drug effects*; D003337:Corpus Callosum / Q000166:cytology; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D017628:Microglia / Q000187:drug effects*; D015398:Signal Transduction
chemical_list: D000255:Adenosine Triphosphate