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Increases in intracellular calcium via activation of an endogenous P 2 ‐purinoceptor in cultured CHO‐K1 cells
Author(s) -
Iredale Philip A.,
Hill Stephen J.
Publication year - 1993
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1993.tb13960.x
Subject(s) - purinergic receptor , calcium , chinese hamster ovary cell , calcium in biology , population , extracellular , biology , intracellular , ppads , receptor , fura 2 , voltage dependent calcium channel , endocrinology , microbiology and biotechnology , biochemistry , medicine , chemistry , biophysics , cytosol , enzyme , environmental health
1 Increases in intracellular calcium ([Ca 2+ ] i ) were measured in Chinese hamster cultured ovary cells (clone, CHO‐K1), by use of the fluorescent, calcium‐sensitive dye, fura‐2. 2 Addition of both ATP and UTP elicited rapid increases in [Ca 2+ ] i due to mobilization from intracellular stores and calcium entry across the plasma membrane. 3 Omission of calcium from the extracellular medium and pre‐incubation with the inorganic calcium channel blocker, nickel (Ni 2+ ) prevented the calcium entry components of the responses. 4 Investigation of the concentration‐response relationships of various analogues of ATP suggests the presence of a purinoceptor which cannot be characterized as P 2X or P 2Y . In addition, there appears to be a sub‐population of P 2Y ‐purinoceptors which do not cross‐react with the ‘nucleotide’ receptor population. 5 Cross‐desensitization and additivity experiments suggest that both ATP and UTP activate the same receptor. 6 Pre‐incubation with the tumour‐promoting agent, β‐phorbol‐12,13 dibutyrate (PDBu), caused a reduction in the increases in [Ca 2+ ] i , suggesting a role for protein kinase C in feedback inhibition of purinoceptor responses in this cell line. 7 In summary, we present evidence for the existence of an endogenous P 2U ‐purinoceptor (or ‘nucleotide receptor’) which is linked to increases in [Ca 2+ ] i in CHO‐K1 cells.