Activation of P2-purino-, alpha 1-adreno and H1-histamine receptors triggers cytoplasmic calcium signalling in cerebellar Purkinje neurons.
The cytoplasmic calcium concentration ([Ca2+]i) was measured from Purkinje neurons in acutely prepared cerebellar slices. Neurons were loaded with calcium indicator Fura-2 by 40-min slice incubation in Tyrode solution containing 5 microM Fura-2/AM and 0.02% pluronic-F127. Bath applications of ATP (100 microM), epinephrine (10 microM) and histamine (100 microM) triggered a transient increase of [Ca2+]i in Purkinje neurons. ATP-induced [Ca2+]i elevation in Purkinje neurons was mimicked by ADP, but not AMP or adenosine pointing to the involvement of P2Y metabotropic purinoreceptors. Epinephrine-triggered [Ca2+]i responses were blocked by the selective alpha 1-antagonist prazosin and were mimicked by the alpha 1-adrenoreceptor agonist phenylephrine, and were not affected by beta- and alpha 2-adrenoreceptor agonists (isoproterenol and clonidine) and antagonists (propranolol and yohimbine). Histamine-induced [Ca2+]i responses demonstrated specific sensitivity to selective H1 antagonist chlorpheniramine, and were not sensitive to H2 and H3 histamine receptors modulators. The [Ca2+]i responses to all three agonists persisted in Ca(2+)-free extracellular media and were blocked by slice preincubation with thapsigargin (500 nM). We conclude that cerebellar Purkinje neurons are endowed with metabotropic P2 gamma purinoreceptors, alpha 1-adrenoreceptors and H1 histamine receptors which mediate the generation of intracellular [Ca2+]i signals via activation of Ca2+ release from inositol-1,4,5-trisphosphate-sensitive intracellular stores.
Kirischuk
S
S
Bogomoletz Institute of Physiology, Kiev, Ukraine.
Matiash
V
V
Kulik
A
A
Voitenko
N
N
Kostyuk
P
P
Verkhratsky
A
A
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002531:Cerebellum / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D011689:Purkinje Cells / Q000187:drug effects*; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects*; D011968:Receptors, Histamine / Q000187:drug effects*; D011983:Receptors, Purinergic / Q000187:drug effects*
D018340:Receptors, Adrenergic, alpha-1; D011968:Receptors, Histamine; D011983:Receptors, Purinergic; D006632:Histamine; D000255:Adenosine Triphosphate; D002118:Calcium; D004837:Epinephrine