Mucosa-Dependent, Stretch-Sensitive Spontaneous Activity in Seminal Vesicle

Area of Science:

• Physiology
• Gastroenterology
• Urology

Background:

• Seminal vesicles (SVs) exhibit spontaneous contractions during ejaculation and inter-ejaculatory phases.
• Recent studies highlight the critical role of SV mucosa in generating this spontaneous activity.
• Stretching SV smooth muscle triggers contractions via action potential firing, slow waves, and Ca2+ flashes.

Purpose of the Study:

• To elucidate the cellular mechanisms underlying spontaneous activity in seminal vesicle smooth muscle.
• To identify the cell types responsible for initiating electrical slow waves in the SV mucosa.
• To investigate the signaling pathways involved in coordinating SV smooth muscle contractions.

Main Methods:

• Electrophysiological recordings and Ca2+ imaging in guinea pig SV preparations.
• Dissection of SV mucosal layers to isolate subepithelial cells.
• Immunohistochemistry to identify cell populations within the SV lamina propria.

Main Results:

• Spontaneous contractions depend on sarco-endoplasmic reticulum (SR/ER) Ca2+ handling and Ca2+-activated chloride channels (CaCCs).
• Electrical slow waves in SV smooth muscle are abolished by gap junction blockade, indicating mucosal origin.
• Spontaneously active subepithelial cells, distinct from known pacemaker cells, drive smooth muscle activity via electrical or humoral signals.

Conclusions:

• The SV mucosa contains spontaneously active subepithelial cells that initiate electrical slow waves.
• These subepithelial cells, potentially involving interstitial cells in the lamina propria, regulate seminal vesicle contractility.
• Understanding these mechanisms is key to comprehending male reproductive physiology and potential dysfunction.