Rapid synchrony of nuclear and cytosolic Ca2+ signals activated by muscarinic stimulation in the human tumour line TE671/RD.
The functional properties of muscarinic cholinergic receptors have been studied in single cells of the TE671/RD human line. Muscarinic stimulation causes large and quick elevations of cytosolic Ca2+ in the majority of the cells; these persist even in the absence of external Ca2+. Electrophysiological experiments reveal, in addition to the expected nicotinic current, the activation of a K(+)-specific current in response to muscarine. The cell nucleus appears freely permeable to the acid form of Fura-2 and the cytosolic Ca2+ changes easily spread into the nucleus, suggesting free diffusion through nuclear pores. Under appropriate Fura-2 loading conditions, fast (up to 0.5 Hz) Ca2+ oscillations can be observed, usually originating from a restricted cytosolic region. This phenomenon is reflected in fast oscillations of the Ca(2+)-activated K+ current.
Giovannardi
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Dipartimento di Fisiologia e Biochimica Generali, Università degli Studi di Milano, Italy.
Cesare
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Peres
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D002118:Calcium / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D002528:Cerebellar Neoplasms / Q000473:pathology; D003600:Cytosol / Q000378:metabolism*; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D008527:Medulloblastoma / Q000473:pathology; D008564:Membrane Potentials / Q000187:drug effects; D009116:Muscarine / Q000494:pharmacology*; D009363:Neoplasm Proteins / Q000187:drug effects / Q000502:physiology; D009685:Nuclear Envelope / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000502:physiology; D015221:Potassium Channels / Q000187:drug effects; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured / Q000187:drug effects
D009363:Neoplasm Proteins; D015221:Potassium Channels; D011976:Receptors, Muscarinic; D009116:Muscarine; D011188:Potassium; D002118:Calcium