Effect of xanthine oxidase-catalyzed reactive oxygen species generation on secretagogue-evoked calcium mobilization in mouse pancreatic acinar cells.
In the present study we have employed fura-2 loaded isolated mouse pancreatic acinar cells to monitor the effect that xanthine oxidase (XOD)-catalyzed reactive oxygen species generation presents on Ca(2+) mobilization by the secretagogue cholecystokinin octapeptide (CCK-8). Our results show that perfusion of pancreatic acinar cells with CCK-8 at a physiological concentration (20 pM) induced low frequency oscillations in intracellular free calcium concentration ([Ca(2+)](i)) at a rate of 1 per minute; this oscillatory pattern was completely inhibited by the introduction in the perifusion medium of 20 mU/mL XOD to generate reactive oxygen species. In addition, perfusion of pancreatic acinar cells with 20 mU/mL XOD in the absence of extracellular calcium led to a transient increase in [Ca(2+)](i,) that blocked the initiation of the Ca(2+) signals in response to 20 pM CCK-8. Similarly, XOD was also able to block acetylcholine evoked Ca(2+) spikes. However, reactive oxygen species had no effect either on Ca(2+) extrusion or on re-uptake into intracellular stores, but CCK-8-evoked Ca(2+) entry was reduced by XOD. In conclusion, our results show that XOD-evoked reactive oxygen species generation leads to a reduction either of Ca(2+) mobilization, following stimulation of pancreatic acinar cells with the Ca(2+)-mobilizing agonists CCK-8 and acetylcholine, and Ca(2+) influx evoked by CCK-8 depletion of intracellular stores. The possible XOD inhibitory mechanism on Ca(2+) mobilization by agonists is discussed.
González-Mateos
A
A
Department of Physiology, University of Extremadura, Faculty of Veterinary Sciences, P.O. Box 643, 10071, Cáceres, Spain. agmateos@unex.es
Camello
P J
PJ
Salido
G M
GM
Pariente
J A
JA
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002384:Catalysis; D004347:Drug Interactions; D008297:Male; D051379:Mice; D010179:Pancreas / Q000187:drug effects* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000494:pharmacology*; D012844:Sincalide / Q000494:pharmacology*; D014969:Xanthine Oxidase / Q000378:metabolism / Q000494:pharmacology*
D017382:Reactive Oxygen Species; D014969:Xanthine Oxidase; D012844:Sincalide; D002118:Calcium