Investigating the role of anoctamin 1 in the calcium dependent depolarisation of the myometrium

The myometrial smooth muscle of the uterus is responsible for force generation during labour, leading to successful delivery and expulsion of the foetus. This contraction occurs as a result of electrical signalling, and the firing of the myometrial action potential. Development of a more detailed understanding the mechanisms that regulate electrical excitability in the myometrium may allow for the identification of new strategies to manage preterm birth and prolonged labour clinically. The calcium activated chloride channel (CaCC) anoctamin 1 (ANO1) has been suggested to play an important role in promoting myometrial contractility, though its potential mechanism is unclear. In this work, a novel model of uterine excitability has been developed to allow investigation of these processes in silico. Simulations run using this model suggest that ANO1 may play a role in initiating the myometrial action potential and coupling the electrical signalling to chemical signalling via oxytocin. ANO1 may also play a role in stabilising and prolonging the action potential. These hypotheses are investigated experimentally using multiple model systems. Cultured immortalised uterine myocytes and intact human tissue were investigated using specific pharmacological inhibition of ANO1 with the novel, potent pharmacological agent Ani9. Experiments using the Cre-Lox system to achieve inducible smooth muscle specific deletion of ANO1 were also carried out. These experiments observed no evidence of ANO1 promoting uterine contractility, suggesting that previously reported findings were the result of non-specific actions of inhibitors. Transcriptional analysis of cultured myocytes and myometrial tissue suggests ANO6 as a potential alternative candidate for forming a CaCC in the myometrium. Simulations also suggest potential roles for the canonical transient receptor protein channel (TRPC6) in initiating the action potential in response to diacyl glycerol generation, and potassium channels such as TWIK-related Potassium Channel 1 (TREK1) in mechano-sensing and regulation of the duration of the myometrial action potential. Plasticity of the myometrial conductome is also considered as a mechanism that underlies the heterogeneity in electrical behaviours between cells, and may dynamically modulate the electrical properties of the cell over physiologically relevant timescales to regulate the action potential. These potential electrophysiological mechanisms are suggested as potential avenues for further investigatio