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Abstract:
Calcium (Ca) is an ubiquitous intracellular messenger which
regulates cellular processes, such as secretion, contraction, and
cell proliferation. A number of different cell types respond to
hormonal stimuli with periodic oscillations of the intracelluar
free calcium concentration ([). These signals are often organized
in complex temporal and spatial patterns even under conditions of
sustained stimulation. Here we study the spatio-temporal aspects of
intracelluar calcium () oscillations in clonal -cells (hamster
insulin secreting cells, HIT) under pharmacological stimulation
(Schofl et al., 1994). We use a novel fast fixed-point algorithm
(Hyvarinen and Oja, 1997) for Independent Component Analysis (ICA)
to blind source separation of the spatio-temporal dynamics of in a
HIT-cell. Using this approach we find two significant independent
components out of five differently mixed input signals: one signal
with a mean oscillatory period of 68 s and a high frequency signal
with a broadband power spectrum with considerable spectral density.
This result is in good agreement with a study on high-frequency
oscillations (Palus et al., 1998). Further theoretical and
experimental studies have to be performed to resolve the question
on the functional impact of intracellular signaling of these
independent signals.
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