Figure 7. Proposed model for mechanically stimulated ATP release in osteoblasts.
Resting Osteoblasts: Under basal conditions, the cell membrane is intact and intracellular free calcium levels and PLC/PKC signaling are minimal. Mechanical injury: Mechanical stimulation results in disruption of the cellular membrane, which leads to the influx of calcium, activation of PLC/PKC signalling, and the efflux of ATP. Membrane repair: The disrupted membrane is rapidly repaired through a process involving Ca2+/PLC/PKC-dependent vesicular exocytosis, thereby limiting ATP release. Cellular adaptation: Elevated PKC levels result in priming of the vesicular pathway, likely regulating cellular resilience and responsiveness to subsequence cycles of mechanical stimulation.