Coarse-grained entropy rates quantify fast Ca2+ dynamics modulated by pharmacological stimulation

Area of Science:

• Cell Biology
• Biophysics
• Endocrinology

Background:

• Intracellular calcium (Ca2+) acts as a crucial messenger regulating diverse cellular functions like secretion and proliferation.
• Hormonal stimulation induces periodic intracellular free Ca2+ concentration ([Ca2+]i) oscillations, typically with periods between 30 seconds and 2 minutes.
• Existing research primarily focuses on high-amplitude, low-frequency [Ca2+]i oscillations.

Purpose of the Study:

• To investigate previously unexplored low-amplitude, high-frequency [Ca2+]i oscillations in hamster insulin-secreting (HIT) cells.
• To analyze the temporal complexity of fast [Ca2+]i dynamics under pharmacological stimulation.
• To identify signaling patterns beyond the established dose-dependent, low-frequency oscillations.

Main Methods:

• Utilized pharmacological stimulation on clonal hamster insulin-secreting (HIT) cells.
• Employed coarse-grained entropy rates derived from information-theoretic functionals.
• Analyzed the temporal complexity of intracellular free Ca2+ concentration ([Ca2+]i) dynamics.

Main Results:

• Demonstrated distinct differences in the temporal complexity of fast, low-amplitude [Ca2+]i oscillations.
• These differences correlate with various phases of pharmacological stimulation.
• Identified these fast oscillations as a novel layer of signaling complexity additional to known low-frequency oscillations.

Conclusions:

• Low-amplitude, high-frequency [Ca2+]i oscillations represent a significant, previously uncharacterized aspect of cellular signaling.
• Temporal complexity analysis reveals distinct dynamic patterns in HIT cells.
• This finding expands our understanding of calcium signaling regulation in insulin secretion.