Effect of pentachlorophenol (PCP) on frog cornea epithelium

Area of Science:

• Environmental Toxicology
• Ocular Physiology
• Membrane Biophysics

Background:

• Pentachlorophenol (PCP) is a known toxicant with adverse effects on multiple tissues.
• The electrophysiological impact of PCP on corneal epithelium, particularly ion transport mechanisms, remains incompletely understood.

Purpose of the Study:

• To investigate the effects of Pentachlorophenol (PCP) on the electrophysiological parameters of the bullfrog cornea epithelium.
• Specifically, to determine PCP's influence on the Na+/K+ ATPase pump, basolateral K+ conductance, and apical Cl- conductance.

Main Methods:

• Experiments utilized an in vitro bullfrog cornea preparation.
• Microelectrodes were employed to measure intracellular potential (Vo) and short-circuit current (Isc).
• Corneas were exposed to 5 x 10-5 M PCP in the tear solution under short-circuit current (Isc) conditions.

Main Results:

• PCP exposure caused a significant decrease in short-circuit current (Isc) and a marked depolarization of intracellular potential (Vo).
• A minimal but significant reduction in apical membrane fractional resistance (fRo) and transepithelial conductance (gt) was observed.
• Experiments in chloride-free solutions indicated PCP inhibits active transepithelial transport and increases basolateral membrane resistance by decreasing K+ conductance.

Conclusions:

• Pentachlorophenol (PCP) inhibits the active transepithelial ion transport mechanism in the bullfrog cornea.
• PCP adversely affects corneal electrophysiology by reducing ion conductance and altering membrane potentials.
• These findings highlight the specific ion transport pathways targeted by PCP toxicity in ocular tissues.