Spontaneous calcium oscillations in urinary bladder smooth muscle cells

Area of Science:

• Physiology
• Developmental Biology
• Cellular Biology

Background:

• Spontaneous phasic activity of detrusor muscle is vital for urinary bladder function.
• Limited information exists on myogenic intracellular calcium ([Ca2+]i) signals in this tissue.

Purpose of the Study:

• To investigate spontaneous, unstimulated [Ca2+]i signals in detrusor muscle cells from newborn guinea pigs.
• To elucidate the mechanisms underlying these [Ca2+]i oscillations and their role in early bladder development.

Main Methods:

• Isolation of detrusor muscle cells from newborn guinea pigs (10-13 days old).
• Measurement of intracellular calcium ([Ca2+]i) using fura-2 fluorescence.
• Application of various pharmacological agents, including ion channel blockers and modulators of intracellular stores.

Main Results:

• 35% of studied detrusor cells displayed spontaneous [Ca2+]i oscillations with diverse kinetic patterns.
• Oscillations were dependent on extracellular Ca2+ influx via L- and T-type channels.
• Intracellular Ca2+ stores, including acidic pools, and Ca2+-activated K+ and Cl- channels modulated these signals.

Conclusions:

• Newborn guinea pig detrusor cells exhibit spontaneous [Ca2+]i oscillations driven by Ca2+ influx and modulated by intracellular stores.
• This oscillatory activity likely contributes to the myogenic function of the urinary bladder during early developmental stages.