Cyclic AMP modulation of ion transport across frog retinal pigment epithelium. Measurements in the short-circuit state.
Open Access
- 31 May 1984
- journal article
- research article
- Published by Rockefeller University Press in The Journal of general physiology
- Vol. 83 (6) , 853-874
- https://doi.org/10.1085/jgp.83.6.853
Abstract
In the frog retinal pigment epithelium (RPE), the cellular levels of cyclic AMP (cAMP) were measured in control conditions and after treatment with substances that are known to inhibit phosphodiesterase (PDE) activity (isobutyl-1-methylxanthine, SQ65442) or stimulate adenylate cyclase activity (forskolin). The cAMP levels were elevated by a factor of 5-7 compared with the controls in PDE-treated tissues and by a factor of 18 in forskolin-treated tissues. The exogenous application of cAMP (1 mM), PDE inhibitors (0.5 mM), or forskolin (0.1 mM) all produced similar changes in epithelial electrical parameters, such as transepithelial potential (TEP) and resistance (Rt), as well as changes in active ion transport. Adding 1 mM cAMP to the solution bathing the apical membrane transiently increased the short-circuit current (SCC) and the TEP (apical side positive) and decreased Rt. Microelectrode experiments showed that the elevation in TEP is due mainly to a depolarization of the basal membrane followed by, and perhaps also accompanied by, a smaller hyperpolarization of the apical membrane. The ratio of the apical to the basolateral membrane resistance increased in the presence of cAMP, and this increase, coupled with the decrease in Rt and the basolateral membrane depolarization, is consistent with a conductance increase at the basolateral membrane. Radioactive tracer experiments showed that cAMP increased the active secretion of Na (choroid to retina) and the active absorption of K (retina to choroid). Cyclic AMP also abolished the active absorption of Cl across the RPE. In sum, elevated cellular levels of cAMP affect active and passive transport mechanisms at the apical and basolateral membranes of the bullfrog RPE.This publication has 33 references indexed in Scilit:
- Induction of dark-adaptive retinomotor movement (cell elongation) in teleost retinal cones by cyclic adenosine 3','5-monophosphate.The Journal of general physiology, 1982
- Fluid transport across retinal pigment epithelium is inhibited by cyclic AMP.Proceedings of the National Academy of Sciences, 1982
- Isolated horizontal cells from carp retina demonstrate dopamine-dependent accumulation of cyclic AMP.Proceedings of the National Academy of Sciences, 1981
- Activation of adenylate cyclase by the diterpene forskolin does not require the guanine nucleotide regulatory protein.Journal of Biological Chemistry, 1981
- Role of cyclic GMP in cholinergic activation of Na-K pump in duck salt glandAmerican Journal of Physiology-Cell Physiology, 1981
- Dopamine receptors: subtypes, localization and regulation.1981
- CYCLIC-NUCLEOTIDES OF CONE-DOMINANT RETINAS - REDUCTION OF CYCLIC-AMP LEVELS BY LIGHT AND BY CONE DEGENERATION1981
- Light-evoked changes in [K+]0 in retina of intact cat eyeJournal of Neurophysiology, 1980
- Effects of changing external potassium and chloride concentrations on the photoresponses of Bufo bufo rods.The Journal of Physiology, 1980
- Localization of frog retinal pigment epithelium Na+-K+ ATPaseExperimental Eye Research, 1980