title: Effects of a myosin light chain kinase inhibitor on the optics and accommodation of the avian crystalline lens.
abstract: OBJECTIVE
  While many studies investigate the cytoskeletal properties of the lens with respect to cataract development, examinations of how these molecular structures interact are few. Myosin light chain kinase (MLCK), actin, and myosin are present on the crystalline lenses of chickens. The purpose of this experiment was to determine whether contractile proteins found on the lens play a role in the optical functions of the lens at rest, and during accommodation.
  
  
  METHODS
  Eyes of 6-day old white Leghorn chicks (Gallus gallus domesticus) were enucleated, with the ciliary nerve intact. One eye was treated with the MLCK inhibitor 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-7) and the other eye with vehicle only. Three concentrations of ML-7 were used: 1 µM, 10 µM, and 100 µM. The back vertex focal lengths (BVFLs) were measured before, during, and after accommodation using an optical laser scanning monitor (Scantox™). To further confirm ML-7 activity, western blotting was performed to detect whether MLCK was inhibited.
  
  
  RESULTS
  Western blots confirmed that MLCK was inhibited at all three ML-7 concentrations. Ten µM ML-7 treatments led to longer BVFLs at rest (p=0.0338), while 100 µM treatments led to opposite changes, resulting in shorter BVFLs (p=0.0220). While 1 µM treatments did not lead to significant optical changes (p=0.4416), BVFLs were similar in pattern to those of the 10 µM group. ML-7 had no effects on accommodative amplitudes (p=0.7848).
  
  
  CONCLUSIONS
  Inhibition of MLCK by ML-7 led to differential changes in BVFLs that presumably affected lenticular integrity. No apparent effect on accommodative amplitudes was observed.
authors: School of Optometry, University of Waterloo, Ontario, Canada.
authors: Sara
authors: S
authors: Luck
authors: Vivian
authors: V
authors: Choh
mesh_terms: D000065:Accommodation, Ocular / Q000187:drug effects* / Q000528:radiation effects; D000818:Animals; D001381:Azepines / Q000494:pharmacology*; D015153:Blotting, Western; D002645:Chickens; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007908:Lens, Crystalline / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D008027:Light; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009281:Naphthalenes / Q000494:pharmacology*; D009924:Organ Culture Techniques
chemical_list: D001381:Azepines; D004791:Enzyme Inhibitors; D009281:Naphthalenes; C070571:ML 7; D009219:Myosin-Light-Chain Kinase