Cytosol-free calcium concentration in single bladder smooth muscle cells from normal and diabetic rats

The effect of diabetes mellitus on intracellular calcium concentration was measured in single rat bladder smooth muscle cells using the fluorescent calcium indicator dye fura-2 AM. Techniques were developed for isolation and short-term culture of rat bladder smooth muscle cells. Cytosol-free calcium concentrations were measured at rest and during carbachol stimulation. Peak intracellular calcium concentration, rate of increase in intracellular calcium concentration and the integral of accumulation of intracellular calcium were determined. The techniques used to isolate and culture bladder smooth muscle cells produced live, physiologically responsive cells. Resting intracellular free calcium levels and were similar in control and diabetic cells. Both control and diabetic cells responded to carbachol stimulation. No significant differences between these cells were noted in peak calcium concentrations, rate of response or integral of response, but standard errors were large. Two patterns of intracellular response to carbachol stimulation were identified, and may explain the large variability in intracellular calcium response to carbachol stimulation.