Effect on Mn2+ on permeability properties of frog skin

Area of Science:

• Physiology
• Biophysics
• Membrane Transport

Background:

• Frog skin is a model for studying epithelial transport.
• Ion permeation across biological membranes is crucial for physiological function.
• Manganese ions (Mn2+) are known to interact with biological systems.

Purpose of the Study:

• To investigate the effects of Mn2+ on frog skin potential difference (PD) and ion transport.
• To elucidate the mechanisms by which Mn2+ influences sodium (Na+) and chloride (Cl-) permeability.
• To differentiate the effects of Mn2+ applied to the inner versus outer bathing solutions.

Main Methods:

• Electrophysiological measurements of PD and short-circuit current (Is.c.).
• Isotopic flux measurements of Na+ and mannitol.
• Experiments conducted in chloride-containing and chloride-free solutions.

Main Results:

• Inner Mn2+ transiently increased PD, decreased conductance, and reduced Na+ and Cl- influx, with isotopic flux reduction exceeding Is.c. reduction.
• Outer Mn2+ increased PD and Is.c. in a chloride-dependent manner, suggesting Cl- retention.
• The effects of inner Mn2+ were attributed to reduced Na+ and Cl- permeation through the outer barrier.

Conclusions:

• Mn2+ differentially affects frog skin ion transport depending on its application site.
• Inner Mn2+ impedes Na+ and Cl- permeation across the outer barrier.
• Outer Mn2+ induces Cl- retention in the bathing solution, influencing electrophysiological parameters.