The Research About Store-operated Ca～(2+) Channel On Distal Colon Smooth Muscle Of Rats And Its Functions

Contraction of smooth muscle cells is triggered by an increase in cytosolic Ca²⁺ upon agonist stimulation. Ca²⁺ influx across the plasma membrane constitutes a major component of the agonist-induced response in smooth muscle cells. Traditionally, voltage-operated Ca²⁺ channel (VOCC) is considered as the channel mediating the Ca²⁺ entry. However, this view has been challenged by recent discoveries which demonstrated that other types of ion channels, such as store-operated and/or receptor-operated Ca²⁺ channels, also participate in Ca²⁺ response induced by agonists in smooth muscle cells. SOCC is defined as the channel activated in response to the depletion of the internal Ca²⁺ stores, an event secondary to G protein coupled receptor or receptor tyrosine kinase stimulation. The Ca²⁺ flow mediated by store-operated Ca²⁺ channel is termed as capacitative Ca²⁺ entry (CCE). Previous study from other group has demonstrated that VOCC played a predominant role in acetylcholine (ACh)-induced contraction of distal colon smooth muscle in Guinea Pig. However, whether SOCC is present in distal colon smooth muscle cells of rats and its functions are unknown. The present study was performed to investigate the role of CCE in the dynamic signal transduction and in ACh-induced mechanical activity of distal colon smooth muscle in rats.1. SOCC activated by store depletion are present in distal colonic smooth muscle cells of ratsIntracellualr Ca²⁺ ([Ca²⁺]_i) changes induced by TG or CAF-activated SOCC were measured in enyzmatically dissociated rat colonic smooth muscle cells with the...