Variations in carbachol- and ATP-induced contractions of the rat detrusor: effects of gender, mucosa and contractile direction.

Purpose: Contractile characteristics of the bladder may depend on variables such as gender, mucosa (MU) and direction of the contractions. However, definitive information is not yet available despite earlier studies on the effects of one variable or another. Here, we explored the differences in the rat detrusor attributable to gender, mucosa and contractile direction.

Methods: K+, carbachol (CCh) and ATP were used as contractile stimuli on rat detrusor strips with and without MU. Contractility was monitored using a myograph system. Both tonic and phasic contractile activities were analyzed.

Results: MU-independent contractions induced by CCh were more potent in females, an effect specific to the longitudinal direction only. The maximal CCh response was larger also in females when MU was removed, suggesting a stronger MU-independent component in the contraction. The larger area under curves of the females under ATP stimulation showed dependence on MU and contractile direction as well. ATP-induced contractions in the males were affected more by MU in the transverse direction than in the females. Direction- and MU-dependent variability of ATP responses was also observed in the males but not in females.

Conclusions: Findings here added new information to the understanding of bladder contractile physiology, providing insights into the quest for better drugs in managing bladder disorders.