Effects of pluronic F-127 on loading of fura 2/AM into single smooth muscle cells isolated from guinea pig taenia coli.

The effect of Pluronic F-127 (PF-127), a surfactant polyol, on the loading of fura 2/AM into smooth muscle cells isolated from guinea pig taenia coli was investigated. The presence of PF-127 during the loading of fura 2 acetoxymethyl ester (fura 2/AM), an intracellular Ca indicator, occasionally increased the incorporation of the dye into the cells. However, long time loading (over approximately 60 min) in the presence of PF-127 decreased the incorporation of fura 2. When the extracellular medium obtained from cells treated with DFP, then incubated with fura 2/AM in the presence of PF-127 was analyzed with excitation spectra, the fluorescence peaks shifted to longer wave lengths by addition of EGTA. However, the peak of the extracellular medium obtained from cells treated with DFP, then incubated without PF-127, did not shift. These results show that PF-127 affects the membranous permeability of the dye in single smooth muscle cells, permitting fura 2 hydrolyzed in the cytoplasm to leak out through the membrane.