Stimulation of Succinate Conversion to CO2 by Supernatant Fluid from Corneal Epithelium

2015 ◽  
pp. 62-67
Author(s):  
J. S. Andrews
Keyword(s):  
Corneal Epithelium ◽  
Supernatant Fluid ◽  
Stimulation Of

Forskolin-induced HCO3- current across apical membrane of the frog corneal epithelium

1990 ◽  
Vol 259 (2) ◽  
pp. C215-C223 ◽  
Author(s):  
O. A. Candia
Keyword(s):  
Corneal Epithelium ◽  
Apical Membrane ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Short Circuit Current ◽  
Pump Current ◽  
Gas Composition ◽  
Apical Side ◽  
Disulfonic Stilbene ◽  
Stimulation Of

Forskolin (and other Cl- secretagogues) does not affect the very small Na(+)-originated short-circuit current (Isc) across frog corneal epithelium bathed in Cl- free solutions. However, forskolin in combination with increased PCO2 bubbling of the solutions (5-20% CO2) stimulated Isc proportionally to PCO2 to a maximum of approximately 8 microA/cm2. This current could be eliminated and reinstated by sequentially changing the gas composition of the bubbling to 100% air and 20% CO2-80% air. The same effects were observed when PCO2 changes were limited to the apical-side solution. Stroma-to-tear HCO3- movement was deemed unlikely, since the increase in Isc was observed with a HCO3(-)-free solution on the stromal side and CO2 gassing limited to the tear side. From the effects of ouabain and tryptamine, at least 80% of the Isc across the basolateral membrane can be accounted for by the Na+ pump current plus K+ movement from cell to bath. Methazolamide also inhibited Isc. Current across the apical membrane cannot be attributed to an electronegative Na(+)-HCO3- symport given the insensitivity of Isc to a disulfonic stilbene and the fact that stroma-to-tear Na+ fluxes did not increase on stimulation of Isc. The tear-to-stroma Na+ flux also remained unaltered, negating an increased apical bath-to-cell Na+ flow. The forskolin-20% CO2 manipulation produced a depolarization of the intracellular potential, a reduction in the apical-to-basolateral resistance ratio, and a decrease in transepithelial resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholinergic stimulation of phosphatidylinositol hydrolysis by rat corneal epithelium in vitro

1987 ◽  
Vol 6 (5) ◽  
pp. 691-701 ◽  
Author(s):  
Keith H. Baratz ◽  
Alan D. Proia ◽  
Gordon K. Klintworth ◽  
Eduardo G. Lapetina
Keyword(s):  
Corneal Epithelium ◽  
Cholinergic Stimulation ◽  
Stimulation Of

Forskolin effects on frog and rabbit corneal epithelium ion transport

1986 ◽  
Vol 251 (3) ◽  
pp. C448-C454 ◽  
Author(s):  
O. A. Candia ◽  
L. R. Grillone ◽  
T. C. Chu
Keyword(s):  
Corneal Epithelium ◽  
Rana Catesbeiana ◽  
Apical Membrane ◽  
Short Circuit ◽  
Control Level ◽  
Short Circuit Current ◽  
Potential Difference ◽  
Ionophore A23187 ◽  
Intracellular Recordings ◽  
Stimulation Of

The effects of forskolin on the electrophysiological parameters of the isolated corneal epithelium from bullfrog (Rana catesbeiana) were investigated. Forskolin stimulated the short-circuit current (SCC) and transepithelial potential difference (PDt), while reducing the transepithelial resistance. These effects were absent in Cl- -free bathing solutions. Furosemide, added either before or after forskolin, completely blocked the effects. Epinephrine and A23187, added after forskolin, produced only a small additional stimulation of the SCC. Propranolol neither blocked nor reduced the effect of forskolin. Forskolin increased the stroma to tear 36Cl flux by 61% and the tear to stroma 36Cl flux by 64%. Intracellular recordings showed that forskolin depolarized the potential difference across the apical membrane and reduced the apical/basolateral resistance ratio. Intracellular recordings in the isolated rabbit epithelium showed the same effects by forskolin except that there was only a brief stimulation of PDt, after which it stabilized slightly below the control level. These results are consistent with an increase in apical membrane permeability similar to that produced by adenosine 3',5'-cyclic monophosphate, epinephrine, and the Ca2+ ionophore A23187.

Stimulation of the synthesis of specific glycoproteins in corneal epithelium by vitamin A

1979 ◽  
Vol 28 (1) ◽  
pp. 23-35 ◽  
Author(s):  
Timothy C. Kiorpes ◽  
Yang-Cha Lee Kim ◽  
George Wolf
Keyword(s):  
Vitamin A ◽  
Corneal Epithelium ◽  
Stimulation Of
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