Are coumarins competitive inhibitors of cytochrome P450 1B1 , with equal potency for allelic variants?
Coumarins are capable of inhibiting carcinogen activation by CYP1B1 with varying potencies, and their efficacy as chemopreventive agents is not likely to be affected by polymorphism in this enzyme.
Preconditioning induces profound retinal tolerance to ischemia in vivo. The absence of a protective effect of preconditioning when there was a 1-hour or a 168-hour separation between the preconditioning stimulus and ischemia and the inhibition of preconditioning by cycloheximide support the hypothesis that a transient change in protein expression is necessary to provide this protection.