Fig. 2.

Store-operated entry of Ca²⁺ in muscle fibers from TRPC1^+/+ and TRPC1^−/− mice. A and B: Ca²⁺ release from the stores was triggered by stimulation with 20 mM caffeine and 1 μM thapsigargin (Tg) in the presence of 1 mM Mn²⁺. This induced an increase of intracellular Ca²⁺ concentration ([Ca²⁺]_i) (reflected by an increase of the fluorescence ratio F₃₄₀/F₃₆₀; B) and an increase of Ca²⁺ entry (reflected by an increase of the quenching rate of fura-PE3 by Mn²⁺; A). C: comparison of fura-PE3 quenching rates by Mn²⁺ at rest (gray bars) and after Ca²⁺ release induced by caffeine and Tg stimulation (black bars representing difference between fura-PE3 quenching rates after and before stimulation) in muscle fibers from TRPC1^+/+ (n = 13) and TRPC1^−/− mice (n = 14). Results are means ± SE.