Effects of neuropeptide Y on the isolated rabbit iris dilator muscle

Invest Ophthalmol Vis Sci. 1988 Feb;29(2):330-2.


The effects of neuropeptide Y (NPY) were studied on an in vitro preparation of rabbit iris dilator muscle. NPY by itself (10(-11) M to 10(-6) M) had no effect on the resting tension or on the maximal electrically-induced response (MER) of the dilator. Phenylephrine (10(-9) M to 10(-4) M) caused a dose-dependent contraction of the dilator muscle (7.8% to 40.6% of the MER). The addition of NPY 10(-6) M enhanced the phenylephrine-induced muscle contraction (8.8% to 76.8% of the MER) without altering the EC50 value (5 X 10(-6) M) of the phenylephrine dose-response curve. These findings support a modulatory role for NPY on the iris dilator muscle.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Electrophysiology
  • In Vitro Techniques
  • Iris / drug effects*
  • Iris / physiology
  • Muscle Contraction / drug effects
  • Muscles / drug effects
  • Muscles / physiology
  • Neuropeptide Y / pharmacology*
  • Osmolar Concentration
  • Phenylephrine / pharmacology
  • Pupil / drug effects
  • Rabbits


  • Neuropeptide Y
  • Phenylephrine