Hyperbaric oxygen effect on active Na+ transport across isolated toad skin

Area of Science:

• Physiology
• Biochemistry
• Toxicology

Background:

• Hyperbaric oxygen therapy (HBO) involves breathing pure oxygen at increased atmospheric pressure.
• Understanding HBO's cellular effects is crucial for optimizing therapeutic applications and mitigating toxicity.
• Sodium transport is vital for maintaining fluid balance and cellular function.

Purpose of the Study:

• To investigate the impact of hyperbaric oxygen (HBO) on sodium (Na+) transport in isolated toad skin.
• To determine the role of amiloride-sensitive pathways and free radicals in HBO-induced toxicity.
• To explore the site-specific effects of HBO and antioxidant enzymes on Na+ transport.

Main Methods:

• Isolated toad skin preparations were exposed to varying partial pressures of oxygen (PO2) at 5, 8, and 10 ATA.
• Transepithelial short-circuit current (ISC) and resistance (R) were measured to assess Na+ transport.
• Amiloride, superoxide dismutase (SOD), and catalase were used to probe the mechanisms of HBO effects.

Main Results:

• HBO exposure caused a dose-dependent decrease in ISC (45-85%) and an increase in R.
• The HBO-induced reduction in ISC was abolished by amiloride, indicating inhibition of Na+ channels.
• Superoxide dismutase and catalase significantly attenuated HBO toxicity, suggesting a role for reactive oxygen species.

Conclusions:

• Hyperbaric oxygen inhibits amiloride-sensitive Na+ transport in toad skin, likely through free radical generation.
• Antioxidant enzymes protect against HBO toxicity, particularly when applied to the serosal side.
• Further research is needed to elucidate the precise cellular and molecular mechanisms of HBO toxicity.