Effects of neuropeptide Y on the isolated rabbit iris dilator muscle.
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.
Piccone
M
M
Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania School of Medicine, Philadelphia 19104.
Littzi
J
J
Krupin
T
T
Stone
R A
RA
Davis
M
M
Wax
M B
MB
D000818:Animals; D004594:Electrophysiology; D066298:In Vitro Techniques; D007498:Iris / Q000187:drug effects* / Q000502:physiology; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000187:drug effects / Q000502:physiology; D009478:Neuropeptide Y / Q000494:pharmacology*; D009994:Osmolar Concentration; D010656:Phenylephrine / Q000494:pharmacology; D011680:Pupil / Q000187:drug effects; D011817:Rabbits
D009478:Neuropeptide Y; D010656:Phenylephrine