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Porcine lung slice model for measuring airway smooth muscle contraction to investigate calcium homeostasis Asthma is characterised by increased airway resistance, which is contributed to by abnormal contraction of the airway smooth muscle (ASM). A greater understanding of the signalling pathways that underlie contraction and their influence on calcium homeostasis may highlight therapeutic opportunities for asthma. This study aimed to optimise the preparation of precision cut lung slices (Bergner and Sanderson, 2002) in pig to provide a bridging model to investigate calcium homeostasis as a prelude to human studies. Concentration dependent airway contractions were observed (often resulting in complete occlusion) for acetylcholine (ACh) (EC50 109.0nM (CI, 69.6nM-170.5nM), n = 3, 3 animals) and histamine (80.29% contraction compared to 100% contraction to 10μM ACh, EC50 3.5μM (CI, 1.5μM-7.9μM), n = 3, 3 animals). Serotonin, a known bronchoconstrictor in many species excluding human, did not induce bronchoconstriction in the pig. Caffeine (20mM) a known ryanodine receptor agonist induced contraction of porcine airways in both 0mM and 2mM extracellular Ca2+. Repeated contractions could only be obtained in the presence of extracellular Ca2+ (n = 6, 3 animals). SERCA pump inhibition of internal calcium store uptake significantly decreased the magnitude of the ACh induced contraction (33.0 + 3.3% reduction, n = 6, 3 animals). These experiments highlight the significance of the internal calcium store for inducing and sustaining ASM contraction. These data demonstrate the potential utility of a porcine lung slice model to investigate calcium homeostasis and highlight interesting species differences in agonist sensitivity, with the porcine system sharing similar pharmacology to human airways.
Bergner, A. and M. J. Sanderson (2002). "Acetylcholine-induced calcium signaling and contraction of airway smooth muscle cells in lung slices." J Gen Physiol 119(2): 187-98.
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