Calcium Fluxes in Work-Related Muscle Disorder: Implications from a Rat Model

Figure 6

A model for possible early and late events in muscle response to HRHF. Exposure to the HRHF task induces an impaired muscle Ca²⁺ homeostasis leading to an increase in [Ca²⁺]_i as indicated by an increase in pCaM. The increased [Ca²⁺]_i may be mediated by leaky RyR1 and/or uptake of extracellular Ca²⁺. Further, HRHF induces muscle metabolic stress indicated by an increase in muscle Hsp72. The increased [Ca²⁺]_i is accompanied by an increased SR vesicle Ca²⁺ uptake rate and SERCA1 together with increased Casq1 which may lead to an enhanced SR Ca²⁺ buffer capacity. The model points to an altered myocellular Ca²⁺ handling as an early adaptation to muscle overload.