Figure 3.

Force relative to extracellular [Ca²⁺] (A) during contractions initiated by increasing [Ca²⁺] at 125 mM KCl in intact urinary bladder preparations of newborn (filled circles), 3-wk-old (open circles), and adult (open squares) mice. B shows force relative to intracellular [Ca²⁺]. Intracellular [Ca²⁺] in Ca²⁺-free solution (at 125 mM KCl) was 373 ± 40.9, 487 ± 80.7, and 582 ± 105 nM in newborn, 3-wk-old, and adult mice (n = 3–5).