Protein expression, biochemical pharmacology of signal transduction, and relation to intraocular pressure modulation by bradykinin B2 receptors in ciliary muscle

Autor: Sharif, Najam A., Xu, Shouxi, Li, Linya, Katoli, Parvaneh, Kelly, Curtis R., Wang, Yu, Cao, Shutong, Patil, Rajkumar, Husain, Shahid, Klekar, Laura, Scott, Daniel
Jazyk: angličtina
Rok vydání: 2013
Předmět:
Zdroj: Molecular Vision
ISSN: 1090-0535
Popis: Purpose To examine the bradykinin (BK) B2-receptor system in human and monkey ciliary muscle (CM) using immunohistochemical techniques, and to pharmacologically characterize the associated biochemical signal transduction systems in human CM (h-CM) cells. BK-induced modulation of intraocular pressure (IOP) in pigmented Dutch-Belt rabbits and cynomolgus monkeys was also studied. Methods Previously published procedures were used throughout these studies. Results The human and monkey ciliary bodies expressed high levels of B2-receptor protein immunoreactivity. Various kinins differentially stimulated [Ca2+]i mobilization in primary h-CM cells (BK EC50=2.4±0.2 nM > Hyp3,β-(2-thienyl)-Ala5,Tyr(Me)8-(®)-Arg9)-BK (RMP-7) > Des-Arg9-BK EC50=4.2 µM [n=3–6]), and this was blocked by B2-selective antagonists, HOE-140 (IC50=1.4±0.1 nM) and WIN-63448 (IC50=174 nM). A phospholipase C inhibitor (U73122; 10–30 µM) and ethylene glycol tetraacetic acid (1–2 mM) abolished the BK-induced [Ca2+]i mobilization. Total prostaglandin (primarily PGE2) secretion stimulated by BK and other kinins in h-CM cells was attenuated by the cyclooxygenase inhibitors bromfenac and flurbiprofen, and by the B2-antagonists. BK and RMP-7 (100 nM) induced a twofold increase in extracellular signal-regulated kinase-1/2 phosphorylation, and BK (0.1–1 µM; at 24 h) caused a 1.4–3.1-fold increase in promatrix metalloproteinases-1–3 release. Topical ocular BK (100 µg) failed to alter IOP in cynomolgus monkeys. However, intravitreal injection of 50 µg of BK, but not Des-Arg9-BK, lowered IOP in rabbit eyes (22.9±7.3% and 37.0±5.6% at 5 h and 8 h post-injection; n=7–10). Conclusions These studies have provided evidence of a functional endogenously expressed B2-receptor system in the CM that appears to be involved in modulating IOP.
Databáze: OpenAIRE