Y-33075 is a selective inhibitor of ROCK derived from Y-27632, and is more potent than Y-27632, with an IC50 of 3.6 nM.

CaMK II:810 nM, ROCK:3.6 nM, PKC:420 nM

Y-33075 (Y-39983) is a potent inhibitor of ROCK(IC50 of 3.6 nM). Y-33075 also inhibits PKC and CaMKII more potently than Y-27632(IC50s of Y-27632 and Y-33075 for PKC are 9.0 μM and 0.42 μM, respectively), whereas the IC50s of Y-27632 and Y-33075 for CaMKII are 26 μM and 0.81 μM, respectively. The IC50s of Y-27632 and Y-33075 for PKC is 82 and 117 times those for ROCK, respectively, whereas the IC50s of Y-27632 and Y-33075 for CaMKII is 236 and 225 times those for ROCK, respectively[1]. Y-33075 (Y-39983, 10 μM) extends neurites in the retinal ganglion cells (RGCs) compared with those in RGCs treated without Y-39983[2]. Y-33075 (Y-39983, 1 μM) inhibits the contraction of rabbit ciliary artery segments evoked by histamine in Ca2+-free solutions[3].

Y-39983 (≥0.01%) significantly lowers intraocular pressure (IOP) at 2 hours after topical administration in rabbits. Y-39983 (0.05%)-treated eyes show significant reduction of IOP between 2 and 7 hours after topical administration in monkeys[1]. Y-39983 (100 μM) increases the regenerating axons of retinal ganglion cells (RGCs) in the eyes of the rats[2].