Colonic motility is controlled by the complex circuitry of the enteric nervous system which regulates the contractility of the longitudinal and circular muscle layers. This circuitry, which consists of sensory neurons, interneurons and motor neurons with diverse firing patterns, is responsible for the complex patterns of motility in the large intestine. Abnormal motility patterns result from alteration, degeneration or disruption of enteric neurons. In the CNS, increases in intracellular calcium concentration ([CA2+]I) are important in regulating the excitability of neurons. The role of [CA2+]I in controlling the excitability of enteric neurons, however, is not well understood.
The aims of this study are, therefore, to investigate how [CA2+]I regulates the activity of functionally identified neurons in the myenteric plexus of the guinea-pig and mouse colon. We will use intracellular microelectrode recordings and patch clamp techniques combined with simultaneous fura-2 imaging of calcium to determine how the excitability of these neurones is regulated by changes in [Ca2+]I, produced by action potentials and synaptic activity. This will involve an examination of the role of calcium influx through various voltage gated calcium channels, the contribution of calcium release from intracellular calcium store and the participation of calcium dependent ion channels in the regulation of neuronal excitability. In the intracellular microelectrode studies neurones will be identified by either intracellular injection of neurobiotin and immunohistochemistry, or by Di-I labeling specific functional classes of neurones (sensory neurones and motor neurones to the circular muscle). In the patch clamp studies we will examine the regulation of the calcium dependent ion channels in freshly dispersed sensory neurons and motor neurons identified by the Di-I-retrograde labeling technique. Finally, we will also examine the diversity of calcium dependent ion channels in these particular neurones using molecular cloning techniques and immunohistochemistry. These studies will further establish that the physiology of functionally different neurones is determined by differences in calcium dependent mechanisms controlling the excitability of neurons which express unique combinations of ion channels. Such knowledge will lead to a greater understanding and more specific design of drugs designed to treat and control motility disorders.

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University of Nevada Reno
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Durnin, Leonie; Kwok, Benjamin; Kukadia, Priya et al. (2018) An ex vivo bladder model with detrusor smooth muscle removed to analyse biologically active mediators released from the suburothelium. J Physiol :
Shi, Junchao; Ko, Eun-A; Sanders, Kenton M et al. (2018) SPORTS1.0: A Tool for Annotating and Profiling Non-coding RNAs Optimized for rRNA- and tRNA-derived Small RNAs. Genomics Proteomics Bioinformatics 16:144-151
Drumm, Bernard T; Sung, Tae S; Zheng, Haifeng et al. (2018) The effects of mitochondrial inhibitors on Ca2+ signalling and electrical conductances required for pacemaking in interstitial cells of Cajal in the mouse small intestine. Cell Calcium 72:1-17
Baker, Salah A; Drumm, Bernard T; Skowronek, Karolina E et al. (2018) Excitatory Neuronal Responses of Ca2+ Transients in Interstitial Cells of Cajal in the Small Intestine. eNeuro 5:
Drumm, Bernard T; Hennig, Grant W; Battersby, Matthew J et al. (2017) Clustering of Ca2+ transients in interstitial cells of Cajal defines slow wave duration. J Gen Physiol 149:703-725
Smith, Terence Keith; Koh, Sang Don (2017) A model of the enteric neural circuitry underlying the generation of rhythmic motor patterns in the colon: the role of serotonin. Am J Physiol Gastrointest Liver Physiol 312:G1-G14
Beckett, Elizabeth A H; Sanders, Kenton M; Ward, Sean M (2017) Inhibitory responses mediated by vagal nerve stimulation are diminished in stomachs of mice with reduced intramuscular interstitial cells of Cajal. Sci Rep 7:44759
Durnin, Leonie; Lees, Andrea; Manzoor, Sheerien et al. (2017) Loss of nitric oxide-mediated inhibition of purine neurotransmitter release in the colon in the absence of interstitial cells of Cajal. Am J Physiol Gastrointest Liver Physiol 313:G419-G433
Cobine, C A; Hannah, E E; Zhu, M H et al. (2017) ANO1 in intramuscular interstitial cells of Cajal plays a key role in the generation of slow waves and tone in the internal anal sphincter. J Physiol 595:2021-2041
Lee, Moon Young; Park, Chanjae; Ha, Se Eun et al. (2017) Serum response factor regulates smooth muscle contractility via myotonic dystrophy protein kinases and L-type calcium channels. PLoS One 12:e0171262

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