Intracellular calcium mobilization following prostaglandin receptor activation in human ciliary muscle cells

Purpose. To investigate the presence of specific prostaglandin receptors in primary cultures of human ciliary muscle cells by measuring agonist-stimulated intracellular calcium mobilization. Methods. The ciliary muscle cells, cultured from postmortem human ciliary muscle explants, were first characterized by antidesmin and anti-smooth muscle alpha-actin antibodies. Increase in intracellular calcium concentrations, in fura 2-AM loaded human ciliary muscle cells stimulated by prostaglandin receptor agonists, were determined with a digital fluorescence imaging system. Results. The resting intracellular calcium concentration in the fura 2-AM loaded cells was 60.0 +/- 6.0 nM. The threshold concentration of PG receptor agonists needed to increase the concentration of intracellular calcium was 10(-8) M. The stimulation of these cells by PGF(2 alpha), 17-phenyl trinor PGE(2), and U46619, the FP, EP1, and TP receptor agonists, resulted in the dose-dependent increase of intracellular calcium. Conclusion. The results of the present study suggest that EP1, FP, and TP receptors are present in human ciliary muscle cells.