Cytoplasmic Ca2+ oscillations evoked by receptor stimulation, G-protein activation, internal application of inositol trisphosphate or Ca2+: simultaneous microfluorimetry and Ca2+ dependent Cl- current recording in single pancreatic acinar cells.
The effects of acetylcholine (ACh), cholecystokinin (CCK), internally applied GTP-gamma-S, inositol trisphosphate [Ins (1,4,5) P3] or Ca2+ on the cytoplasmic free Ca2+ concentration [( Ca2+]i) were assessed by simultaneous microfluorimetry (fura-2) and measurement of the Ca2(+)-dependent Cl- current (patch-clamp whole-cell recording) in single internally perfused mouse pancreatic acinar cells. ACh (0.1-0.2 microM) evoked an oscillating increase in [Ca2+]i measured in the cell as a whole (microfluorimetry) which was synchronous with oscillations in the Ca2(+)-dependent Cl- current reporting [Ca2+]i close to the cell membrane. In the same cells a lower ACh concentration (0.05 microM) evoked shorter repetitive Cl- current pulses that were not accompanied by similar spikes in the microfluorimetric recording. When cells did not respond to 0.1 microM ACh, caffeine (1 mM) added on top of the sustained ACh stimulus resulted in [Ca2+]i oscillations seen synchronously in both types of recording. CCK (10 nM) also evoked [Ca2+]i oscillations, but with much longer intervals between slightly broader Ca2+ pulses. Internal perfusion with 100 microM GTP-gamma-S evoked [Ca2+]i oscillations with a similar pattern. Ins (1,4,5) P3 (10 microM) evoked repetitive shortlasting spikes in [Ca2+]i that were only seen in the Cl- current traces, except in one small cell where these spikes were also observed synchronously in the microfluorimetric recording. Caffeine (1 mM) broadened these Ca2+ pulses. [Ca2+]i was also directly changed, bypassing the normal signalling process, by infusion of a low or high Ca2+ solution into the pipette.(ABSTRACT TRUNCATED AT 250 WORDS)
MRC Secretory Control Research Group, University of Liverpool, UK.
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Osipchuk
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Wakui
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Yule
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Gallacher
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Petersen
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001572:Benzofurans; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D018118:Chloride Channels; D002712:Chlorides / Q000502:physiology*; D002766:Cholecystokinin / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000502:physiology*; D051379:Mice; D010179:Pancreas / Q000187:drug effects / Q000502:physiology*; D013050:Spectrometry, Fluorescence; D013873:Thionucleotides / Q000494:pharmacology
D001572:Benzofurans; D018118:Chloride Channels; D002712:Chlorides; D005456:Fluorescent Dyes; D007473:Ion Channels; D008565:Membrane Proteins; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D015544:Inositol 1,4,5-Trisphosphate; D006160:Guanosine Triphosphate; D002766:Cholecystokinin; D019204:GTP-Binding Proteins; D000109:Acetylcholine; D002118:Calcium; D016257:Fura-2