INTRACELLULAR CALCIUM MOBILIZATION FOLLOWING PROSTAGLANDIN RECEPTOR ACTIVATION IN HUMAN CILIARY MUSCLE-CELLS

Purpose. To investigate the presence of specific prostaglandin recepto rs in primary cultures of human ciliary muscle cells by measuring agon ist-stimulated intracellular calcium mobilization. Methods. The ciliar y 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 prostagland in receptor agonists, were determined with a digital fluorescence imag ing system. Results. The resting intracellular calcium concentration i n the fura 2-AM loaded cells was 60.0 +/- 6.0 nM. The threshold concen tration of PG receptor agonists needed to increase the concentration o f intracellular calcium was 10(-8) M. The stimulation of these cells b y PGF(2 alpha), 17-phenyl trinor PGE(2), and U46619, the FP, EP1, and TP receptor agonists, resulted in the dose-dependent increase of intra cellular calcium. Conclusion. The results of the present study suggest that EP1, FP, and TP receptors are present in human ciliary muscle ce lls.