Calcium signaling induced by angiotensin II in the pancreatic acinar cell line AR42J.
The purpose of this study was to characterize the nature and mechanisms of angiotensin II-evoked calcium signaling in AR42J cells. Cytosolic calcium concentrations were determined using fura-2-based microfluorimetry. Angiotensin II causes elevations in free cytosolic calcium ([Ca2+]i) in the rat pancreatic acinar cell line AR42J. The mechanisms of angiotensin II-evoked calcium signaling were examined using fura-2-based fluorescent digital microscopy. Angiotensin II caused dose-dependent increments in [Ca2+]i over a concentration range of 0.1-1,000 nM, with an average increment of 243 +/- 16 nM at an angiotensin II concentration of 1,000 nM. Dup753, an AT1-specific antagonist, inhibited angiotensin II-evoked signaling, whereas the AT2 antagonist PD123,319 had no effect. Preincubation with the phospholipase C inhibitor U73122 reduced the response in [Ca2+]i to 25% of that of the control. Thapsigargin abolished angiotensin II-evoked calcium signaling. The inositol 1,4,5-trisphosphate receptor antagonist heparin introduced by radiofrequency electroporation inhibited responses to 46 +/- 6% of controls. Angiotensin II-evoked signals were reduced in magnitude and duration by elimination of Ca2+ from the extracellular buffer. Preincubation with pertussis toxin (100 ng/ml) had no effect. Angiotensin II did not stimulate cyclic AMP or suppress vasoactive intestinal peptide stimulated cyclic AMP production over the concentration range that caused Ca2+ signaling.
Barnhart
D C
DC
Department of Surgery, University of Michigan, Ann Arbor 48109-0331, USA.
Sarosi
G A
GA
Romanchuk
G
G
Mulholland
M W
MW
D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology; D020013:Calcium Signaling / Q000187:drug effects*; D002460:Cell Line; D000242:Cyclic AMP / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D018274:Electroporation; D004963:Estrenes / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism; D010179:Pancreas / Q000187:drug effects* / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
D004963:Estrenes; D007093:Imidazoles; D011725:Pyridines; D011760:Pyrrolidinones; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin; D000804:Angiotensin II; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C073402:PD 123319; D014660:Vasoactive Intestinal Peptide; D019284:Thapsigargin; D000242:Cyclic AMP; D010738:Type C Phospholipases; D002118:Calcium