Sources of calcium in agonist-induced contraction of rat distal colon smooth muscle in vitro

Figure 3 Role of Ca²⁺ in rat distal colon contraction. A: Representative results showing that removal of extracellular Ca²⁺ abolished contraction induced by high K⁺ and 5 &mgr;mol/L ACh. Summarized data showing that tension induced by high K⁺ and 5 &mgr;mol/L ACh before, during and after application of Ca²⁺-free Krebs solution. ^bP < 0.01, ^dP < 0.001 vs Control; B: Representative results showing that chelation of extracellular Ca²⁺ with 2.78 mmol/L EGTA abolished contraction induced by high K⁺ and 5 &mgr;mol/L ACh. Summarized data showing that tension induced by high K⁺ and 5 &mgr;mol/L ACh in the presence of EGTA ^bP < 0.01, ^fP < 0.001 vs-EG (before).