Iono- and metabotropically induced purinergic calcium signalling in rat neocortical neurons.
ATP receptor-mediated Ca2+ concentration changes were recorded from neocortical neurones in brain slices from 2 week-old rats. To measure the cytoplasmic concentration of Ca2+ ([Ca2+]i) slices were incubated with fura-2/AM, and the microfluorimetry system was focused on an individual cell. During transients the intracellular level of [Ca2+]i in the majority of neocortical neurones (98 of 102) varied in the concentration range of ATP 5-2000 microM between 41. 3+/-5 and 163+/-7 nM. The rank order of efficacy for purinoreceptor agonists in concentration 100 microM was: ATPgammaS>ATP>ADP>>AMP approximately Adenosine approximately alpha,beta-methylene ATP>UTP. 10 microM PPADS, a P2-purinoreceptor antagonist, reduced the ATP-induced [Ca2+]i response by 26%+/-4%. After elimination of calcium from extracellular solution the first ATP-induced [Ca2+]i transient decreased to 65+/-8%, suggesting the participation of metabotropic P2y triggered Ca-release in the generation of the transient. Elevation of cytosolic Ca2+ by activation of plasmalemmal Ca2+ channels failed to potentiate such release indicating the absence of effective reloading of the corresponding stores. No Ca2+-induced Ca2+-release has been observed in the investigated neurons.
Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Bogomoletz St., 4, 252024 Kyiv-24, Ukraine.
U
U
Lalo
N
N
Voitenko
P
P
Kostyuk
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009994:Osmolar Concentration; D058913:Purinergic Agonists; D051381:Rats; D017208:Rats, Wistar; D011983:Receptors, Purinergic / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*
D015220:Calcium Channels; D058913:Purinergic Agonists; D011983:Receptors, Purinergic; D002110:Caffeine; D000255:Adenosine Triphosphate; D002118:Calcium