Mitochondria are one of the most important organelles determining Ca2+
regulatory pathway in the cell. Recent experiments suggested the existence of cytosolic
microdomains with locally elevated calcium concentration (CMDs) in the nearest vicinity of
the outer mitochondrial membrane (OMM). These intermediate physical connections between
endoplasmic reticulum (ER) and mitochodria are called MAM (mitochondria-associated ER
membrane) complexes.
The aim of this paper is to take into account the direct calcium flow
from ER to mitochondria implied by the existence of MAMs and perform detailed numerical
analysis of the influence of this flow on the type and shape of calcium oscillations.
Depending on the permeability of MAMs interface and ER channels, different patterns of
oscillations appear (simple, bursting and chaotic). For some parameters the oscillatory
pattern disappear and the system tends to a steady state with extremely high calcium level
in mitochondria, which can be interpreted as a crucial point at the beginning of an
apoptotic pathway.