Inositol phosphate-diacylglycerol signaling pathway in regulation of intraocular pressure.
To clarify the role of the inositol phosphate diacylglycerol (PI) signaling pathway in the regulation of intraocular pressure (IOP), we examined the effects of the tumor promoter phorbol ester (PMA) and Ca ionophore A23187 on IOP responses in albino rabbits. It was known that PMA stimulates protein kinase C (PKC) directly and that A23187 elevates intracellular Ca2+ concentration. In this study, the topical application of 10 microM PMA or 15 microM A23187 slightly reduced IOP. However, when both 10 microM PMA and 15 microM A23187 were topically applied the IOP was significantly reduced between 2 and 10 hours after A23187 application. The maximum IOP decrease was 5.0 mmHg at 3 hours. This decrease was inhibited by pretreatment with 0.5 microM staurosporin, a PKC inhibitor. These findings suggest that the PI signaling pathway somehow mediates aqueous dynamic changes in the eye.
Nagata
A
A
Department of Ophthalmology, Hiroshima University School of Medicine, Japan.
Mishima
H K
HK
Okamura
N
N
Ishibashi
S
S
Choshi
K
K
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001082:Aqueous Humor / Q000502:physiology; D000001:Calcimycin / Q000494:pharmacology; D004075:Diglycerides / Q000502:physiology*; D007295:Inositol Phosphates / Q000502:physiology*; D007429:Intraocular Pressure / Q000187:drug effects / Q000502:physiology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011817:Rabbits; D015398:Signal Transduction / Q000502:physiology*; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D004075:Diglycerides; D007295:Inositol Phosphates; D000001:Calcimycin; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate