EFFECTS OF H-7 ON THE IRIS AND CILIARY MUSCLE IN MONKEYS

Objectives: To determine the effects of H-7 on (1) iris and ciliary mu scles (CMs) in living monkeys; (2) isolated monkey CM strips; (3) acto myosin contractility in cultured Swiss 3T3 cells. Methods: (1) Pupilla ry diameter (calipers) and accommodation (refractometer) in living mon keys were measured after topical, intracameral, or intravitreal admini stration of H-7 followed by systemic pilocarpine hydrochloride. (2) Pi locarpine-induced contraction of isolated monkey CM strips following a dministration of H-7 was measured in a perfusion chamber. (3) Actomyos in contractility in Swiss 3T3 cells cultured on thin silicone rubber f ilm was determined by measuring cell-induced film wrinkles before and after administration of H-7. Results: Topical H-7 prevented anesthesia -induced miosis but did not affect resting refraction. Intracameral or intravitreal H-7 dilated the pupil and inhibited miotic but not accom modative responses to pilocarpine. H-7 inhibited pilocarpine-induced c ontraction of isolated monkey CM strips and reduced Swiss 3T3 cell con traction. Conclusions: H-7 inhibits actin-based contractility in non-m uscle cells and in monkey iris sphincter and CM. Under our in vivo exp erimental conditions, the effect on the iris predominates over that on the CM.