Calcium oscillation coupled

Pasti L, Zonta M, Pozzan T, Vicini S, Carmignoto G (2001) Cytosolic calcium oscillations in astrocytes may regulate exocytotic release of glutamate. J Neurosci 21 477 84 Fenner R, Neher E (1988) The role of calcium in stimulus-secretion coupling in excitable and non-excitable cells. J Exp Biol 139 329-345... 

Information is also encoded within the frequency of Ca + oscillations that occur in the cytosol. Oscillations can derive either from fluctuations of the entry of external calcium or of the release from internal stores. The former occur primarily in excitable cells, after the periodic opening of plasma membrane Ca + channels, such as induced, for example, by the rhythmic changes of the plasma membrane potential of the heart or by bursts of action potential in neurons. In nonexcitable cells, the predominant mechanism of [Ca +]c elevation is from the activation of plasma membrane receptors coupled to G-proteins... 

The IP3R and RyR are examples of FKBP 12 functioning as an adapter or coupling molecule, assembling macromolecular complexes involved in cell signaling pathways. In its role of regulating the conductance properties of the receptors and their phosphorylation states, FKBP 12 may modulate generation of calcium waves or oscillations. 

A simple model for coupled Ca +-IP3 oscillations contains three variables (see Fig. 4.1) cytoplasmic and total calcium concentration c and. 2, and the IP3 concentration p. Here we assume that the (in)activation of the IP3R by Ca and IP3 is fast compared to other processes. The Ca " " concentration in the ER s is related to the total concentration by s = (2 — c)//3, where /3 is the ratio of effective cytoplasmic volume to effective ER volume. The time changes of the three variables are described by... 

In formulating the mechanism of the proton pump, we require the presence of certain nonlinearities to find the possibility of changing the dissipation, or the efficiency, with an oscillatory input of ATP. The minimum elements of a proton pump, although nonlinear, lead only to monotone relaxation kinetics, and thus only to decreases in efficiency upon imposition of an oscillatory influx of ATP. However, by including the coupling of other ion transport processes, such as those of potassium and calcium, the mechanism of the proton pump behaves like a damped oscillator, which has been observed in experiments... 

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