Figure 6.

Two experiments on contraction of smooth muscle cells A7r5 with transient transfections of the cytosolic fusion protein β-galactosidase (SNAP-β-gal) employed for the labeling with TMR. Contraction was initiated with [Arg⁸]-vasopressin (AVP). (A₂ and B₂) Triplet lifetime image with color-encoded lifetime. (A₃ and B₃) Temporal evolution of the average triplet relaxation rate for the region inside the white rectangle. The result indicates a variation in the oxygen concentration after a monoexponential decay (the approximate decay parameter was estimated from multiple experiments). We used (A) τ_isc = 2.12 μs and (B) τ_isc = 2.01 μs; both values were obtained by global fitting on several measurements. The image quality was optimized for multiple measurements. A typical triplet lifetime image with higher spatial resolution can be found in the Supporting Material.