Table 1.

SERCA activity in mouse hindlimb muscles

Muscle	Genotype	KCa, pCa	ΔKCa
Soleus	+/+	6.85 ± 0.01	–
	−/−	6.95 ± 0.03*	0.10
EDL	+/+	6.71 ± 0.02	–
	−/−	6.73 ± 0.01	0.02
White gastrocnemius	+/+	6.80 ± 0.01	–
	−/−	6.76 ± 0.03	−0.04
Red gastrocnemius	+/+	6.72 ± 0.03	–
	−/−	6.84 ± 0.03*	0.12

Values are means ± SE. Homogenates were isolated from wild-type (+/+) and Sln-null (−/−) mouse hindlimb muscles and were analyzed for Ca²⁺-ATPase activity over Ca²⁺ concentrations ranging from pCa 8 to pCa 5 to obtain K_Ca. K_Ca is the negative logarithm of the Ca²⁺ concentration required to attain the half-maximal Ca²⁺-ATPase activity rate. SERCA, sarco(endo) plasmic reticulum Ca²⁺-ATPase; EDL, extensor digitorum longus.

^*P < 0.05, statistically significant (Sln-null vs. wild-type mice).