Angiotensin II-mediated signal transduction events in cystic fibrosis pancreatic duct cells.
Different signal transduction pathways, i.e. Ca2+- and cAMP-dependent, involved in mediating the effects of angiotensin II (AII) were investigated separately using the short-circuit current (Isc) technique and radioimmunoassay (RIA) in a cystic fibrosis pancreatic cell line (CFPAC-1) which exhibits defective cAMP-dependent but intact Ca2+-dependent anion secretion. The AII-induced Isc could be inhibited by the specific antagonist for AT1, losartan (1 microM), but not the antagonist for AT2, PD123177 (up to 10 microM). The AII-induced Isc was also reduced by the treatment of the cells with a Ca2+ chelator, BAPTA-AM (100 microM), indicating a dependence of the AII-induced anion secretion on the intracellular Ca2+. Treatment of the cells with pertussis toxin (0.1 microg/ml) or a phospholipase C (PLC) inhibitor, U73122 (5 microM), resulted in a substantial reduction in the AII-induced Isc indicating involvement of Gi and PLC in the Ca2+-dependent anion secretion. RIA measurements showed that AII stimulated an increase in cAMP production which could be reduced by losartan, pertussis toxin and U73122 but not BAPTA-AM. In addition, inhibitors of cyclooxygenase, indomethacin (10 microM) and piroxicam (10 microM), did not have any effect on the AII-induced cAMP production, excluding the involvement of prostaglandins. Our results suggest that both AII-stimulated cAMP and Ca2+-dependent responses are mediated by the AT1 receptor and Gi-coupled PLC pathway. However, the AII-stimulated cAMP production in CFPAC-1 cells is not dependent on Ca2+ or the formation of prostaglandins.
Cheng
H S
HS
Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
So
S C
SC
Law
S H
SH
Chan
H C
HC
D000804:Angiotensin II / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D003550:Cystic Fibrosis / Q000378:metabolism; D004963:Estrenes / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D010183:Pancreatic Ducts / Q000378:metabolism; D037342:Pertussis Toxin; D011760:Pyrrolidinones / Q000494:pharmacology; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D010738:Type C Phospholipases / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D004963:Estrenes; D011760:Pyrrolidinones; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin; D010566:Virulence Factors, Bordetella; D000804:Angiotensin II; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D000242:Cyclic AMP; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D002118:Calcium