Distribution and Ca2+ signalling of fibroblast‐like (PDGFRα+) cells in the murine gastric fundus
Year: 2013
Type: article
Abstract: Key points A new class of interstitial cells, PDGFRα+ cells, is distributed densely in the proximal stomachs of mice. PDGFRα+ cells express the molecular apparatus necessary for transduction of inputs from enteric inhibitory motor neurons. PDGFRα+ cells generate spontaneous Ca2+ transients and display dynamic Ca2+ oscillations in response to purines. Purinergic responses are mediated by P2Y1 receptors and by Ca2+ release from intracellular Ca2+ stores. Ca2+ release in PDGFRα+ cells is the likely means by which purinergic neurotransmitters activate Ca2+‐activated K+ channels (SK) and hyperpolarization in GI muscles to elicit inhibitory motor responses. Spontaneous Ca2+ transients may be a means of regulating basal excitability of fundus muscles and release of purines from motor neurons may contribute to the control of pressure during filling in the proximal stomach. Abstract Platelet‐derived growth factor receptor α positive (PDGFRα+) cells are suggested to mediate purinergic inputs in GI muscles, but the responsiveness of these cells to purines in situ has not been evaluated. We developed techniques to label and visualize PDGFRα+ cells in murine gastric fundus, load cells with Ca2+ indicators, and follow their activity via digital imaging. Immunolabelling demonstrated a high density of PDGFRα+ cells in the fundus. Cells were isolated and purified by fluorescence‐activated cell sorting (FACS) using endogenous expression of enhanced green fluorescent protein (eGFP) driven off the Pdgfra promoter. Quantitative PCR showed high levels of expression of purinergic P2Y1 receptors and SK3 K+ channels in PDGFRα+ cells. Ca2+ imaging was used to characterize spontaneous Ca2+ transients and responses to purines in PDGFRα+ cells in situ. ATP, ADP, UTP and β‐NAD elicited robust Ca2+ transients in PDGFRα+ cells. Ca2+ transients were also elicited by the P2Y1‐specific agonist (N)‐methanocarba‐2MeSADP (MRS‐2365), and inhibited by MRS‐2500, a P2Y1‐specific antagonist. Responses to ADP, MRS‐2365 and β‐NAD were absent in PDGFRα+ cells from P2ry1(−/−) mice, but responses to ATP were retained. Purine‐evoked Ca2+ transients were mediated through Ca2+ release mechanisms. Inhibitors of phospholipase C (U‐73122), IP3 (2‐APB), ryanodine receptors (Ryanodine) and SERCA pump (cyclopiazonic acid and thapsigargin) abolished Ca2+ transients elicited by purines. This study provides a link between purine binding to P2Y1 receptors and activation of SK3 channels in PDGFRα+ cells. Activation of Ca2+ release is likely to be the signalling mechanism in PDGFRα+ cells responsible for the transduction of purinergic enteric inhibitory input in gastric fundus muscles.
Source: The Journal of Physiology
Institution: University of Nevada, Reno
Language: English
Subfield: Gastroenterology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W1569474087