Smooth muscle cells were freshly isolated from the rat tail main artery under the following conditions: a 5-mm long piece of artery was incubated at 37°C for 40–45 min in 2 ml of 0.1 mM Ca2+ external solution containing 20 mM taurine, 1.35 mg/ml collagenase (type XI), 1 mg/ml soybean trypsin inhibitor, and 1 mg/ml BSA, which was lightly bubbled with a 95% O2–5% CO2 gas mixture to gently agitate the enzyme solution. Cells were stored in 0.05 mM Ca2+ external solution containing 20 mM taurine and 0.5 mg/ml BSA at 4°C under normal atmosphere, and were used for experiments within 2 days following isolation (Fusi et al., 2016).