Cell-specific patterns of oscillating free Ca2+ in carbamylcholine-stimulated insulinoma cells.
The effect of the muscarinic agonist carbamylcholine on cytoplasmic Ca2+ concentration ([Ca2+]i was examined at the single cell level in clonal pancreatic beta-cells (HIT). Cells were loaded with the indicator dye fura 2, and [Ca2+]i was measured by microfluorimetry. Carbamylcholine induced changes in Ca2+ that differed from cell to cell and provoked in some cells oscillatory Ca2+ fluctuations. During a transient, free Ca2+ rose to a peak within 1-3 s. The frequency of the oscillations increased with agonist concentration. Oscillations in [Ca2+]i occurred in the absence of external Ca2+. When cells were perifused for a sufficient period of time without carbamylcholine, near identical Ca2+ responses were elicited in each cell by successive applications of the agonist. Thus, individual cells displayed characteristic and reproducible Ca2+ responses with respect to amplitude, frequency, and shape of the transients as well as latency in onset of the initial Ca2+ rise. We propose that the biological response to a Ca2+ agonist in a given cell is not only determined by the frequency and amplitude of Ca2+ oscillations but is governed by the unique pattern of the Ca2+ signal of each cell, which may be termed "Ca2+ fingerprint."
Prentki
M
M
Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia 19104.
Glennon
M C
MC
Thomas
A P
AP
Morris
R L
RL
Matschinsky
F M
FM
Corkey
B E
BE
D007516:Adenoma, Islet Cell / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology*; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D005470:Fluorometry; D006706:Homeostasis; D007340:Insulinoma / Q000378:metabolism*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000378:metabolism*
D002217:Carbachol; D002118:Calcium