Troglitazone inhibits bicarbonate secretion in rat and human duodenum

Area of Science:

• Gastroenterology
• Pharmacology
• Physiology

Background:

• Troglitazone is an oral antidiabetic agent used for non-insulin-dependent diabetes mellitus.
• A known side effect of troglitazone is edema.
• The mechanism by which troglitazone induces edema is not fully understood but may involve intestinal ion transport.

Purpose of the Study:

• To investigate the effects of troglitazone on intestinal ion transport and water absorption.
• To elucidate the ionic basis for troglitazone-induced changes in duodenal mucosa.

Main Methods:

• Short circuit current (I(sc)) measurements were performed on rat and human duodenal mucosa in Ussing chambers.
• Experiments involved serosal addition of troglitazone and preadministration of various agents including acetazolamide, amiloride, tetrodotoxin, and vasoactive intestinal peptide.
• Cyclic AMP (cAMP) content in rat duodenal mucosa was measured after incubation with troglitazone.

Main Results:

• Troglitazone caused a dose-dependent decrease in I(sc) in both rat and human duodenal mucosa.
• The decrease in I(sc) was partially dependent on bicarbonate secretion and was enhanced by vasoactive intestinal peptide.
• Troglitazone significantly reduced cyclic AMP content in rat duodenal mucosa.

Conclusions:

• Troglitazone inhibits electrogenic bicarbonate secretion in the duodenal mucosa.
• This inhibition of ion transport may contribute to the development of edema associated with troglitazone therapy.
• Further research is warranted to fully understand the implications of troglitazone's effects on intestinal physiology.