Figure 1. Sensitivity of cAMP levels to increased hydrostatic pressure in ONH astrocytes. In both AA (white bars) and CA (black bars) astrocytes, 500 μM IBMX stimulated cAMP, but pressure induced additional cAMP only in AA astrocytes. The basal cAMP levels in AA (59.6 pmol/mg protein) and CA (61.6 pmol/mg protein) astrocytes are not significantly different. The change in cAMP levels in AA astrocytes due to pressure stimulation is significant (p<0.01, double asterisk, n=8), and the difference between AA and CA astrocytes in terms of cAMP produced at 15 and 30 min of hydrostatic pressure is also significant (p<0.05, asterisk, n=8). Error bars indicate standard error of the mean.