However, our results from three separate experiments failed to sup port a role for PKC in carbachol induced dispersion. Treatment with the PKC activator PMA did not induce pig ment granule dispersion. Neither of the PKC inhibitors tested inhibited carbachol selleck chem induced pigment granule dispersion at most concentrations tested. Cells treated with bisindolylmale imide II at 200 nM experienced a 20% inhibition in dis persion relative to the carbachol treated cells when data from the latter were compiled from all experiments. How ever, when comparison was made only to the carbachol treated cells from the experiment in which the 200 nM concentration was tested, the difference in mean pigment indices was not found to be statistically significant.

This case was the only one in which the compilation of the data yielded a statistical outcome different from analysis of the data within single experiments. Nevertheless, it remains possible that PKC has a role in carbachol medi ated dispersion which parallels the main pathway linking receptor activation to pigment granule movement. Inhibitors,Modulators,Libraries It should be mentioned that definitive evidence that PKC is expressed in bluegill RPE has yet to be found. We have Inhibitors,Modulators,Libraries found that PKC and PKC were expressed in bluegill brain, but not in bluegill RPE. These findings are consistent with work reported by oth ers. In the retina of zebrafish, PKC labelling is observed in the neural retina, but not in the retinal pigment epithe lium. Although much remains to be discovered, our results have increased our understanding of the pathway from carba chol to pigment granule dispersion.

We propose the fol lowing model First, carbachol binds an Modd muscarinic receptor leading to PLC activation. PLC then cleaves PIP2 into DAG and IP3. Inhibitors,Modulators,Libraries A role for DAG in pigment movement in RPE has not been revealed. In contrast, IP3 binds its receptor, thus releasing Ca2 from intracellular stores. Although the conclusion requires support from Ca2 imaging, our data indicates that Ca2 released from such stores is sufficient for downstream mediator activation. in other words, extracellular Ca2 is not required. Increasing cytosolic Ca2 leads to calcineurin activation. Calcineurin removes phosphate groups added by PKA on an as yet unidentified protein which functions as a molecular switch regulating the pigment granule posi tion in the retinal Inhibitors,Modulators,Libraries pigment epithelium.

Refer to Figure 6 for the proposed carbachol induced dispersion pathway. Possibledispersionpathway for carbachol induced pigment Conclusion Our results indicated that in the RPE of bluegill, carba chol Inhibitors,Modulators,Libraries induced pigment granule dispersion is a process Crenolanib side effects that requires intracellular, but not extracellular, Ca2. Our evi dence also supports a pigment dispersion model that requires calcineurin but not protein kinase C. Methods Experimental animals The experimental animals were maintained as described previously.