Adenosine and ATP effects on isolated guinea pig gallbladder

Area of Science:

• Pharmacology
• Gastroenterology
• Physiology

Background:

• The role of purinergic signaling in gallbladder motility is not fully understood.
• Adenosine and adenosine triphosphate (ATP) are key signaling molecules with diverse physiological effects.

Purpose of the Study:

• To investigate the effects of adenosine, ATP, and their derivatives on isolated guinea pig gallbladder strips.
• To elucidate the potential involvement of prostaglandins and adenosine metabolism in these responses.

Main Methods:

• Isolated organ bath studies were performed on guinea pig gallbladder strips.
• Concentration-response curves were generated for adenosine, ATP, and adenosine derivatives.
• The effects of theophylline, HNBTG, indomethacin, and adenosine deaminase were assessed.

Main Results:

• Adenosine produced dose-dependent relaxations, antagonized by theophylline and potentiated by HNBTG.
• ATP primarily induced contractile effects, which were abolished by indomethacin, suggesting prostaglandin involvement.
• Adenosine deaminase diminished adenosine's effects and partially reduced ATP-induced relaxations.
• Adenosine derivatives showed variable relaxant efficacy, with none achieving maximal response at 100 µM.

Conclusions:

• Adenosine mediates relaxant effects in the guinea pig gallbladder, modulated by uptake and enzymatic degradation.
• ATP's contractile effects are likely mediated by prostaglandins.
• The low potency of adenosine and ATP suggests their physiological roles in gallbladder motility may be limited.