Acute oxidative stress modulates secretion and repetitive Ca2+ spiking in rat exocrine pancreas.
The effects of the oxidant tert-butylhydroperoxide (t-buOOH) on carbachol-stimulated pancreatic secretion in the vascularly perfused rat pancreas have been studied in parallel with [Ca2+]i signalling and amylase output in perifused rat pancreatic acinar cells. Perfusion of the pancreas with t-buOOH (0.1-1 mM) caused a rapid and irreversible inhibition of carbachol-stimulated (3x10-7 M) amylase and fluid secretion. Pre-perfusion of the pancreas with vitamin C and dithiothreitol or a cocktail of GSH and GSH-precursor amino acids provided only marginal protection against the deleterious effects of t-buOOH, even though GSH levels were elevated significantly. In perifused pancreatic acini, repetitive [Ca2+]i spikes evoked by carbachol (3x10-7 M) were sustained for 40 min. t-buOOH (1 mM) acutely increased the amplitude and duration of Ca2+ spikes, then attenuated Ca2+ spiking and subsequently caused a marked and sustained rise in [Ca2+]i. t-buOOH-induced alterations in carbachol-stimulated [Ca2+]i signalling and amylase release in perifused pancreatic acini were prevented by vitamin C. Although vitamin C restored impaired Ca2+ signalling and maintained amylase output in pancreatic acini, it seems likely that oxidative stress inhibits fluid secretion irreversibly in the intact pancreas, resulting in a loss of amylase output. Thus, perturbations in [Ca2+]i signalling may not fully explain the secretory block caused by oxidative stress in acute pancreatitis.
Sweiry
J H
JH
Division of Physiology, GKT School of Biomedical Sciences, King's College London, Campden Hill Road, London W8 7AH, UK.
Shibuya
I
I
Asada
N
N
Niwa
K
K
Doolabh
K
K
Habara
Y
Y
Kanno
T
T
Mann
G E
GE
D000681:Amylases / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000037:antagonists & inhibitors; D005978:Glutathione / Q000494:pharmacology; D008297:Male; D008298:Maleates / Q000494:pharmacology; D018384:Oxidative Stress; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism*; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
D000975:Antioxidants; D008298:Maleates; D002217:Carbachol; D020122:tert-Butylhydroperoxide; D000681:Amylases; C014476:diethyl maleate; D005978:Glutathione; D001205:Ascorbic Acid; D002118:Calcium