Purchase this article with an account.
A. K. Cheng, K. M. Leung, K. Chan, H. Y. Chung, K. Peterson-Yantorno, C. W. Do, M. M. Civan; Potential Role of cAMP in Regulating Aqueous Humor Secretion in Mammalian Eye. Invest. Ophthalmol. Vis. Sci. 2009;50(13):817.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To determine the net vectorial effects of cAMP on fluid transport across the ciliary epithelia of mammalian eyes.
Freshly isolated porcine ciliary body was excised and mounted in modified Ussing-Zerahn-type chamber. Electrical parameters including transepithelial potential difference (PD), short-circuit current (Isc) and transmural resistance (Rt) were continuously monitored. In addition, fluid transfer across the native bovine ciliary body preparation was studied.
Transepithelial PD and Isc were found to be 1.0 mV (aqueous side negative) and 12 µA/cm2, respectively across the porcine ciliary epithelium. Addition of 1-100 µM 8-bromo-cAMP to the aqueous side caused a sustained increase in Isc by ~80%. At 10 and 100 µM, cAMP further triggered a transient stimulation of Isc (up to ~110%) before reaching the steady-state plateau. Under low bathing Cl- concentration, the cAMP-induced sustained Isc stimulation was completely inhibited. Fluid transport across the intact bovine ciliary body was increased by 40-50% after applying 1 mM of dibutyryl-cAMP to the aqueous surface, and by ~100% after application to the stromal side.
cAMP has previously been found to modify transporters and gap junctions in ways that might stimulate or inhibit fluid secretion. Under the present conditions, the net effect of cAMP was to stimulate net transport of both ions and fluid. The results suggest that cAMP’s multiple oppositely-directed effects can be integrated to stimulate inflow, in addition to the inhibition noted previously.
This PDF is available to Subscribers Only