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Benninger RKP, Hutchens T, Head WS, McCaughey MJ, Zhang M, Le Marchand SJ, Satin LS, Piston DW. Intrinsic islet heterogeneity and gap junction coupling determine spatiotemporal Ca²⁺ wave dynamics. Biophys J 2014; 107:2723-33. [PMID: 25468351 DOI: 10.1016/j.bpj.2014.10.048] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/09/2014] [Accepted: 10/08/2014] [Indexed: 10/24/2022] Open
Abstract
Insulin is released from the islets of Langerhans in discrete pulses that are linked to synchronized oscillations of intracellular free calcium ([Ca(2+)]i). Associated with each synchronized oscillation is a propagating calcium wave mediated by Connexin36 (Cx36) gap junctions. A computational islet model predicted that waves emerge due to heterogeneity in β-cell function throughout the islet. To test this, we applied defined patterns of glucose stimulation across the islet using a microfluidic device and measured how these perturbations affect calcium wave propagation. We further investigated how gap junction coupling regulates spatiotemporal [Ca(2+)]i dynamics in the face of heterogeneous glucose stimulation. Calcium waves were found to originate in regions of the islet having elevated excitability, and this heterogeneity is an intrinsic property of islet β-cells. The extent of [Ca(2+)]i elevation across the islet in the presence of heterogeneity is gap-junction dependent, which reveals a glucose dependence of gap junction coupling. To better describe these observations, we had to modify the computational islet model to consider the electrochemical gradient between neighboring β-cells. These results reveal how the spatiotemporal [Ca(2+)]i dynamics of the islet depend on β-cell heterogeneity and cell-cell coupling, and are important for understanding the regulation of coordinated insulin release across the islet.
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Affiliation(s)
- Richard K P Benninger
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee; Department of Bioengineering, University of Colorado, Aurora, Colorado; Barbara Davis Center, University of Colorado, Aurora, Colorado.
| | - Troy Hutchens
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee
| | - W Steven Head
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Michael J McCaughey
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Min Zhang
- Department of Pharmacology, Virginia Commonwealth University, Richmond, Virginia
| | - Sylvain J Le Marchand
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Leslie S Satin
- Department of Pharmacology, Virginia Commonwealth University, Richmond, Virginia; Department of Pharmacology, University of Michigan, Ann Arbor, Michigan; Brehm Diabetes Center, University of Michigan, Ann Arbor, Michigan
| | - David W Piston
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, Tennessee.
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Using pancreas tissue slices for in situ studies of islet of Langerhans and acinar cell biology. Nat Protoc 2014; 9:2809-22. [PMID: 25393778 DOI: 10.1038/nprot.2014.195] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Studies on the cellular function of the pancreas are typically performed in vitro on its isolated functional units, the endocrine islets of Langerhans and the exocrine acini. However, these approaches are hampered by preparation-induced changes of cell physiology and the lack of an intact surrounding. We present here a detailed protocol for the preparation of pancreas tissue slices. This procedure is less damaging to the tissue and faster than alternative approaches, and it enables the in situ study of pancreatic endocrine and exocrine cell physiology in a conserved environment. Pancreas tissue slices facilitate the investigation of cellular mechanisms underlying the function, pathology and interaction of the endocrine and exocrine components of the pancreas. We provide examples for several experimental applications of pancreas tissue slices to study various aspects of pancreas cell biology. Furthermore, we describe the preparation of human and porcine pancreas tissue slices for the validation and translation of research findings obtained in the mouse model. Preparation of pancreas tissue slices according to the protocol described here takes less than 45 min from tissue preparation to receipt of the first slices.
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