Correlation between the structure and function of the rabbit urinary bladder following partial outlet obstruction

Area of Science:

• Urology
• Cell Biology
• Physiology

Background:

• Partial bladder outlet obstruction (PBOO) is a common condition affecting bladder function.
• Understanding the relationship between structural changes and functional decline in the detrusor smooth muscle (SM) is crucial for managing PBOO.

Purpose of the Study:

• To investigate the correlation between contractile dysfunction and ultrastructural/innervation alterations in the rabbit bladder following PBOO.
• To characterize the temporal progression of these changes over a 70-day period.

Main Methods:

• Rabbits underwent mild partial outlet obstruction for 1-70 days.
• Contractile responses to field stimulation (FS) and carbachol were measured in isolated bladder strips.
• Ultrastructural analysis of detrusor smooth muscle was performed using electron microscopy.

Main Results:

• Bladder mass increased significantly within the first 7 days post-obstruction.
• Contractile response to FS (nerve-mediated) declined earlier and more rapidly than carbachol response (receptor-mediated).
• Ultrastructural changes included smooth muscle cell hypertrophy, myofilament disorganization, mitochondrial swelling, and axonal degeneration, with no evidence of regeneration.

Conclusions:

• Prolonged PBOO leads to progressive detrusor smooth muscle contractile dysfunction.
• Structural damage, including ischemia suggested by mitochondrial damage, underlies the observed functional decline.
• The findings highlight the detrimental impact of PBOO on bladder wall integrity and function.