Ascaris suum: characterization of transmural and hypodermal potentials

Area of Science:

• Parasitology
• Electrophysiology
• Molecular Biology

Background:

• Parasitic nematodes possess an electrochemical potential across their body wall.
• Understanding this potential is key to comprehending nematode physiology and developing targeted treatments.

Purpose of the Study:

• To investigate the ionic dependence of the transmural electrical potential (Etm) in the gastrointestinal nematode Ascaris suum.
• To characterize the barrier properties of the Ascaris suum body wall components: cuticle and hypodermis.

Main Methods:

• Conventional electrophysiological techniques were employed.
• Ussing chamber experiments were performed on isolated Ascaris suum body wall segments.
• Ionic concentrations and temperature were manipulated to assess their effects on electrical potentials.

Main Results:

• The transmural electrical potential (Etm) in Ascaris suum was measured at -40 +/- 12 mV.
• The body wall potential was more sensitive to external acetate than Na+, K+, or Cl-.
• The cuticle demonstrated high permeability to ions (K+ > Na+ = Cl- > acetate- > gluconate-).
• Hypodermal membranes exhibited distinct potentials (Ei = -47.6 +/- 6 mV, Eo = -74.9 +/- 7 mV).
• Potentials were depolarized by reduced temperature, indicating temperature-dependent mechanisms.

Conclusions:

• The Ascaris suum cuticle/hypodermis complex exhibits differential permeability to inorganic and organic ions.
• Active ion transport or diffusion of metabolic products likely contributes significantly to maintaining electrochemical gradients.
• These findings offer insights into nematode ion transport and potential targets for antiparasitic interventions.