Ocular hypotension induced by intravitreally injected C-type natriuretic peptide.
The purpose of the study is to determine if intravitreal injection of c-type natriuretic peptide (CNP) affects intraocular pressure (IOP), aqueous humor dynamics and guanosine 3',5'-cyclic monophosphate (cGMP) concentration in the aqueous humor of the rabbit eye. Also we investigated whether CNP-like immunoreactivities (CNP-LI) were present in porcine aqueous humor and whether CNP-LI were detected in rabbit and porcine ciliary body. The IOP was measured after intravitreal injection of 2 pmol approximately 20 nmol CNP into rabbit eyes. Aqueous humor dynamics (aqueous humor flow, outflow facility, and uveoscleral outflow) and cGMP concentration in the aqueous humor were determined at approximately 6 hr after CNP injection. The CNP concentration in aqueous was measured by radioimmunoassay in porcine eye, and CNP-LI were detected with a monoclonal antibody in porcine and rabbit eyes. Intravitreally injected CNP caused IOP reduction in a dose-dependent manner (P<0.0001) and the maximum effect was observed at 4 approximately 6 hr. CNP increased total outflow facility by approximately 35%, but did not affect aqueous humor flow or uveoscleral outflow. The cGMP concentration in the aqueous of CNP-treated eyes was about 4- to 14-fold higher than that in the contralateral untreated eyes. CNP concentration in aqueous was about 2-fold higher than that in plasma, and CNP-LI were found in non-pigmented epithelium of the ciliary body of both rabbit and porcine eyes. CNP may play an important role in the regulation of IOP.
Takashima
Y
Y
Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Taniguchi
T
T
Yoshida
M
M
Haque
M S
MS
Igaki
T
T
Itoh
H
H
Nakao
K
K
Honda
Y
Y
Yoshimura
N
N
D000818:Animals; D001082:Aqueous Humor / Q000737:chemistry / Q000502:physiology; D006152:Cyclic GMP / Q000378:metabolism; D007150:Immunohistochemistry; D007429:Intraocular Pressure / Q000187:drug effects; D020098:Natriuretic Peptide, C-Type; D015814:Ocular Hypotension / Q000139:chemically induced*; D011506:Proteins / Q000009:adverse effects*; D011817:Rabbits; D013552:Swine; D013997:Time Factors
D011506:Proteins; D020098:Natriuretic Peptide, C-Type; D006152:Cyclic GMP