Influence of transepithelial potential difference on acidification in the toad urinary bladder.

Area of Science:

• Physiology
• Renal Physiology
• Cell Biology

Background:

• The urinary bladder plays a crucial role in regulating urine composition and pH.
• Understanding the mechanisms of urinary acidification is vital for comprehending renal function.
• Transepithelial potential difference (PD) is a key electrophysiological parameter in epithelial transport.

Purpose of the Study:

• To investigate the relationship between transepithelial potential difference (PD) and the rate of urinary acidification in toad bladders.
• To determine the influence of sodium transport on PD-driven acidification.
• To elucidate the pathway utilized by PD-driven acidification.

Main Methods:

• In vitro measurement of urinary acidification rates in toad urinary bladders.
• Monitoring pH changes in mucosal and serosal Ringer's solutions.
• Manipulation of transepithelial potential difference (PD) using imposed voltages and ion substitutions (choline for Na).
• Inhibition studies using amiloride and acetazolamide.

Main Results:

• Urinary acidification rate showed a linear correlation with transepithelial potential difference (PD) within a tested range.
• A favorable PD enhanced acidification rates, independent of spontaneous sodium transport.
• Acetazolamide inhibited both active and PD-driven acidification.
• PD-driven acidification correlated linearly with short-circuit acidification rates.

Conclusions:

• Transepithelial potential difference (PD) can accelerate urinary acidification in toad bladders, even without active sodium transport.
• The PD-driven component of acidification appears to utilize a transcellular pathway.
• These findings contribute to understanding the electrophysiological regulation of urinary acidification.