ABSTRACT
In many visceral smooth muscle organs such as the gastrointestinal (GI) tract, upper and lower urinary tract systems, and lymphatic vessels, the contractility of smooth muscle cells (SMCs) can be modulated by the activity of non-contractile interstitial cells (ICs). In the GI tract, SMCs and ICs comprise the SIP syncytium. The integrated activity of SIP cells tunes the excitability of GI smooth muscles and predetermines to some extent responses to enteric motor neurons and hormones. The main cell population of the muscle layers of the GI tract consists of SMCs with ICs representing a small percentage of the total population about 10%. The ionic conductances responsible for generating slow waves and neural responses in ICs can be investigated at both the tissue and single-cell level. Ca2+ imaging studies of ICs outside of the GI tract have primarily focused on interstitial cells of Cajal-LCs on the single-cell level.
