Ca < sup > 2+ < /sup > dynamics in interstitial cells: foundational mechanisms for the motor patterns in the gastrointestinal tract

Physiol Rev. 2023 Aug 10. doi: 10.1152/physrev.00036.2022. Online ahead of print.ABSTRACTThe gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGFRa+ cells. Together these cells form the SIP syncytium. ICC and PDGFRa+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRa+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transientsoccur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarization (STDs). Neurotransmission increases or decreases Ca2+transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains ac...
Source: Physiological Reviews - Category: Physiology Authors: Source Type: research