Simultaneous recordings of calcium signals and mechanical activity using fluorescent dye fura 2 in isolated strips of vascular smooth muscle.

In rat aortic strips loaded with a Ca2+ indicator, fura 2, the Ca2+ signal and contractile tension were simultaneously recorded. On the addition of high K+ or noradrenaline, the 500 nm fluorescence produced by excitation at 340 nm increased and that produced by excitation at 380 nm decreased. EGTA decreased the 340 nm fluorescence and increased the 380 nm fluorescence in resting and stimulated muscles. Tension changes were always preceded by fluorescent changes.