ALDH7A1 and alkaline phosphatase measurement: Nor were significant protective effects seen on pancreatic blood flow with the 25 mg/kg caffeine regimen, to be expected if mediated via PDE inhibition.38 Since pancreatic cellular injury initiates and determines severity in AP, the protective effect of caffeine on AP is likely to have been mediated by inhibition of IP3R-mediated Ca2+ release.