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Calcium release from separate receptor‐specific intracellular stores induced by histamine and ATP in a hamster cell line.
Author(s) -
Den Hertog A,
Hoiting B,
Molleman A,
Van den Akker J,
Duin M,
Nelemans A
Publication year - 1992
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1992.sp019281
Subject(s) - histamine , extracellular , intracellular , hyperpolarization (physics) , chemistry , purinergic receptor , agonist , biophysics , medicine , endocrinology , calcium , mepyramine , calcium in biology , cyclopiazonic acid , hamster , antagonist , receptor , biology , biochemistry , stereochemistry , nuclear magnetic resonance spectroscopy
1. The specificity of intracellular Ca2+ stores to Ca(2+)‐mobilizing agonists was studied in DDT1 MF‐2 vas deferens cells of the Syrian hamster. 2. Application of histamine (100 microM) or ATP (100 microM) to the DDT1 MF‐2 cells caused an initial increase of intracellular Ca2+ followed by a lower phase as measured by using Indo‐1 as fluorescent probe at 22 degrees C. The basal Ca2+ level (146 nM) was enhanced to 309 nM by histamine and to 379 nM by ATP. 3. A transient rise in intracellular Ca2+ lasting for about 2 min was measured in the presence of histamine or ATP in the absence of extracellular Ca2+. The basal Ca2+ level (78 nM) was increased to 128 nM by histamine and to 145 nM by ATP. 4. A transient hyperpolarization was elicited in single cells as measured with microelectrodes by both agonists under Ca(2+)‐free conditions with a similar time course as the change in internal Ca2+. The hyperpolarization observed in the presence of histamine amounted to 23 mV and 31 mV with ATP. The histamine‐induced responses were abolished by the H1 histaminoceptor antagonist mepyramine (10 microM) and the responses evoked by ATP were blocked by the P2 purinoceptor antagonist suramin (300 microM). 5. A second internal Ca2+ response could only be evoked under Ca(2+)‐free conditions by applying a higher agonist concentration or after replenishing the intracellular stores with Ca2+ from the extracellular space. 6. A second addition of an optimal concentration (100 microM) of the agonist to the cells under Ca(2+)‐free conditions did not evoke mobilization of internal Ca2+ or hyperpolarization, but resulted in a rise of the cellular inositol (1,4,5)‐trisphosphate content (Ins(1,4,5)P3) as determined by a radioligand binding assay. 7. The cells responded to both agonists (100 microM) with a transient Ca2+ response if successively applied at a maximal effective concentration (100 microM) under Ca(2+)‐free conditions. 8. Simultaneous stimulation of H1 histaminoceptors and P2 purinoceptors resulted in the absence of external Ca2+ in an additional increase in internal Ca2+ represented by the amplitude and area of the response and in an increased response area of the hyperpolarization.(ABSTRACT TRUNCATED AT 400 WORDS)