Ammonia transport by the turtle bladder: relationship to H+ secretion

Area of Science:

• Physiology
• Renal Physiology
• Urothelial Transport

Background:

• Turtle bladders transport ammonia (NH3 and NH4+).
• The relationship between ammonia transport and hydrogen ion (H+) secretion is not fully understood.
• Unstirred layers and chemical reactions may influence transport dynamics.

Purpose of the Study:

• To investigate the link between ammonia transport and H+ secretion in turtle bladders.
• To determine the role of unstirred layers and chemical reactions in ammonia transport.
• To examine how inhibiting or stimulating H+ secretion affects ammonia transport.

Main Methods:

• Examined ammonia transport into mucosal solution.
• Assessed H+ secretion before and after inhibition with acetazolamide, SITS, and dicyclohexylcarbodiimide.
• Investigated effects of CO2 stimulation and varying buffer concentrations.

Main Results:

• Inhibitors of H+ secretion significantly decreased both H+ secretion and ammonia transport.
• CO2 stimulation increased both H+ secretion and ammonia transport.
• Ammonia transport was electrogenic, pH-dependent, and correlated with H+ secretion, but NH3 diffusion was not.

Conclusions:

• Ammonia transport in turtle bladders is closely linked to H+ secretion.
• H+ secretion plays a significant role in regulating ammonia transport.
• Unstirred layer chemistry influences ammonia transport dynamics.