Effects of pregnancy on urethral and bladder neck function

Area of Science:

• Urology
• Physiology
• Pharmacology

Background:

• Pregnancy and menopause cause significant morphologic and functional changes in the female urethra.
• Urinary symptoms like frequency, urgency, and incontinence are common during these periods.
• These symptoms are often attributed to hormonal influences on autonomic receptors in the urinary tract.

Purpose of the Study:

• To compare the functional responses of the bladder neck and urethra in pregnant versus virgin rabbits.
• To investigate the impact of pregnancy on the compliance and autonomic receptor distribution in these tissues.

Main Methods:

• Isolated muscle strips from the bladder neck and urethra of pregnant and virgin New Zealand White rabbits were used.
• Passive length-tension studies were conducted.
• Functional responses to field stimulation (FS) and autonomic agonists (phentolamine, atropine, phenylephrine) were analyzed.

Main Results:

• Muscle strips from pregnant rabbits showed significantly greater compliance.
• Pregnancy altered the inhibitory effects of phentolamine and atropine on FS-induced contractions.
• Urethral strips from pregnant rabbits exhibited reduced contractile responses to phenylephrine compared to virgin rabbits.
• Field-stimulated relaxation was significantly greater in urethral strips from virgin rabbits than pregnant rabbits.

Conclusions:

• Pregnancy-induced hormonal changes profoundly alter the compliance and functional responses of the bladder neck and urethra.
• These alterations in autonomic stimulation and relaxation responses may underlie pregnancy-related urinary symptoms.