Spontaneous synaptic drive in detrusor smooth muscle: computational investigation and implications for urinary...

Area of Science:

• Physiology
• Computational Biology
• Smooth Muscle Electrophysiology

Background:

• The detrusor, a smooth muscle in the bladder wall, is syncytial and densely innervated.
• Spontaneous excitatory junction potentials (SEJPs) arise from neurotransmitter release at neuromuscular junctions (NMJs).
• Integration of SEJPs is crucial for generating action potentials and focal contractions during bladder filling.

Purpose of the Study:

• To develop a biophysically constrained computational model of the detrusor syncytium with distributed innervation.
• To explore spatio-temporal integration of SEJPs and identify key contributing factors.
• To provide a framework for investigating detrusor electrical activity in normal and pathological states.

Main Methods:

• Developed a computational model of detrusor smooth muscle syncytium with spatially distributed innervation.
• Validated the model against experimental data to ensure physiological realism.
• Conducted comparative studies to analyze the influence of coupling strength and innervation density.

Main Results:

• Model validation confirmed congruence between theoretical predictions and experimental observations.
• Integrated SEJP amplitude is most sensitive to inter-cellular coupling strength.
• Frequency of events is more strongly dependent on innervation density.

Conclusions:

• Spontaneous neurotransmitter release frequency may contribute to detrusor overactivity.
• Patchy denervation could alter detrusor electrical activity during pathology.
• The model serves as a realistic framework for studying passive potential spread and integration in innervated syncytial tissues.