Connexins 43 and 45 hemichannels mediate ATP release in the urinary bladder

Area of Science:

• Cell Biology
• Physiology
• Biochemistry

Background:

• Connexins (Cx) form gap junctions for intercellular communication.
• Connexins also form hemichannels that release adenosine triphosphate (ATP) into the extracellular space.
• Extracellular ATP acts on purinergic receptors, influencing cellular signaling.

Purpose of the Study:

• To investigate the roles of Cx43 and Cx45 in adenosine triphosphate (ATP) release from urinary bladder cells.
• To determine how hypotonic stretch and calcium depletion affect ATP release mediated by Cx43 and Cx45.
• To elucidate the contribution of Cx hemichannels to bladder sensory mechanisms.

Main Methods:

• Immunofluorescence staining for Cx43 and Cx45 in porcine bladder tissues and cultured cells.
• Assessment of Cx43- and Cx45-mediated ATP release in response to hypotonic stretch and extracellular Ca2+ depletion.
• Utilized Cx43 and Cx45 mimetic peptides to block hemichannel activity and measure effects on ATP release.

Main Results:

• Cx43 and Cx45 expression was confirmed in porcine urothelial, suburothelial, detrusor muscle cells, and human RT4 cells.
• Hypotonic stretch and Ca2+ depletion significantly increased ATP release in urothelial cells and RT4 cells.
• Blockade of Cx43 and Cx45 channels reduced stretch- and Ca2+-induced ATP release, with greater impact in urothelial cells.

Conclusions:

• Cx hemichannels regulate ATP release in the bladder through mechanotransduction and Ca2+-sensitive pathways.
• ATP acts as an autocrine/paracrine signaling molecule during bladder distension.
• Findings provide new insights into bladder sensory mechanisms involving connexin hemichannels.