Abstract
We have examined statistical relationships between the amplitudes and the kinetics (rise times, fall times, and decay constants) of cytosolic free calcium fluctuations (spikes) in a population of 353 individual GH4C1 rat pituitary cells. The fast falling phase was approximated by a single exponential decay, and the decay time constant, tau, increased linearly with spike amplitude in 80% of the cells studied. The slope of the tau versus amplitude plot for each cell was inversely related to the cell's mean spike amplitude. Thus, some process responsible for prolonging the decay phase of spikes appeared to operate strongly in cells with spikes of low amplitude, but to become less prominent in cells with high amplitude spikes. Mean tau correlated more strongly with mean rise and fall times than with mean spike amplitude, indicating that the kinetic properties of spikes were not tightly coupled to spike amplitude. These findings are consistent with a model wherein the rise phase corresponds to entry of extracellular calcium via L-type calcium channels into localized sub-plasmalemmal domains, followed by diffusion of subplasmalemmal calcium into the cell interior; and the falling phase corresponds to further calcium diffusion combined with activation of cytoplasmic calcium-induced calcium release, which prolongs the falling phase.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
