TY - JOUR
T1 - Effects of tertiary amine local anesthetics on ion transport in the isolated bullfrog cornea
AU - Schoen, Howard F.
AU - Candia, Oscar A.
N1 - Funding Information:
The authors thank Astra Pharmaceutical Products, Sterling Winthrop Research Institute, E. R. Squibb and Sons,a nd Eli Lilly and Co. for their generousg ifts of someo f the drugs used in this study. The researchw as supported by NIH Grants EY 0016~a nd EY 01867.H oward F. Schoenisa Postdoctoral Trainees upportedby NIH Grant EY 0’7014. A preliminary account of this work was presented at the Spring, 1977, meeting of the Association for Researchi n Vision and Ophthalmology.
PY - 1979/2
Y1 - 1979/2
N2 - Corneas were mounted in Ussing-type chambers and their short-circuit current (SCC) and resistance measured. Of eight local anesthetics tested, four (benoxinate, etidocaine, lidocaine, and mepivacaine) stimulated the SCC when added to the epithelial bathing solution at concentrations of from 0·02 to 1 mm. The stimulation, which usually lasted for 40-60 min, was seen only when the Ringer's solution contained Cl. At higher concentrations or after longer incubations, these local anesthetics inhibited the SCC. Four other local anesthetics, dibucaine, tetracaine, proxymetacaine (proparacaine), and procaine, only inhibited the Cl-dependent SCC when added to the epithelial bathing solution, with ID50's (after 60 min) of about 0·04, 0·3, 2 and 10 mm, respectively. Stimulation of the SCC was always accompanied by a reduction in the transcorneal electrical resistance. Inhibition of the SCC was accompanied by an increase, decrease, or no change in resistance. In some cases where the SCC was inhibited, the resistance fell to very low levels, but this effect was often partially reversed when the drug was washed out of the chamber. It is suggested that local anesthetics inhibit the SCC by directly altering the chloride permeability of corneal epithelial cells. The explanation for the stimulatory effect is less clear, but could be due to an elevation of intracellular Ca levels or to hormone-like effects of the drugs.
AB - Corneas were mounted in Ussing-type chambers and their short-circuit current (SCC) and resistance measured. Of eight local anesthetics tested, four (benoxinate, etidocaine, lidocaine, and mepivacaine) stimulated the SCC when added to the epithelial bathing solution at concentrations of from 0·02 to 1 mm. The stimulation, which usually lasted for 40-60 min, was seen only when the Ringer's solution contained Cl. At higher concentrations or after longer incubations, these local anesthetics inhibited the SCC. Four other local anesthetics, dibucaine, tetracaine, proxymetacaine (proparacaine), and procaine, only inhibited the Cl-dependent SCC when added to the epithelial bathing solution, with ID50's (after 60 min) of about 0·04, 0·3, 2 and 10 mm, respectively. Stimulation of the SCC was always accompanied by a reduction in the transcorneal electrical resistance. Inhibition of the SCC was accompanied by an increase, decrease, or no change in resistance. In some cases where the SCC was inhibited, the resistance fell to very low levels, but this effect was often partially reversed when the drug was washed out of the chamber. It is suggested that local anesthetics inhibit the SCC by directly altering the chloride permeability of corneal epithelial cells. The explanation for the stimulatory effect is less clear, but could be due to an elevation of intracellular Ca levels or to hormone-like effects of the drugs.
KW - chloride transport
KW - corneal epithelium
KW - corneal permeability
KW - electrical resistance
KW - short-circuit current
KW - sodium transport
UR - http://www.scopus.com/inward/record.url?scp=0018755679&partnerID=8YFLogxK
U2 - 10.1016/0014-4835(79)90131-3
DO - 10.1016/0014-4835(79)90131-3
M3 - Article
C2 - 312737
AN - SCOPUS:0018755679
SN - 0014-4835
VL - 28
SP - 199
EP - 209
JO - Experimental Eye Research
JF - Experimental Eye Research
IS - 2
ER -