FIGURE 5.

Absence of Ba²⁺-dependent facilitation and deactivation of SOCE in the fetal skeletal muscle. (A) Representative traces of Mn-quenching in a fetal skeletal muscle with passively depleted SR Ca²⁺ store (after incubation in 0 Ca²⁺ for 1 h). Fifty seconds after perfusion of 2 mM BaCl₂ to the bath solution, the Mn²⁺-quenching rate remained unchanged, demonstrating the lack of Ba²⁺-dependent facilitation of SOCE. (B) In a separate muscle cell, 5 min after perfusion of 2 mM BaCl₂ to the bath solution, the Mn²⁺-quenching rate remained constant as the control, suggesting the lack of Ba²⁺-dependent deactivation of SOCE. (C) Data from five experiments were averaged. Clearly, the Mn²⁺-quenching rates did not differ significantly from the control, at t < 1 min or >3 min after perfusion of Ba²⁺ to the bath solution.