Somatostatin inhibition of phosphoinositides turnover in isolated rat acinar pancreatic cells: interaction with bombesin.
The effects of somatostatin-14 and bombesin on [3H]inositol phosphate accumulation were studied in 24 h myo-[3H]inositol-prelabeled cultured rat acinar cells. Bombesin, 10 nM, stimulated basal formation of phosphatidyl monophosphate (InsP1), phosphatidyl 4,5-biphosphate (InsP2) and inositol 1,4,5-triphosphate (InsP3) by 128 +/- 5.2%, 147 +/- 10% and 155 +/- 5%, respectively. At 5 s, the ED50 value for InsP3 stimulation was 0.70 +/- 0.2 nM. This stimulation was partly blocked (64 +/- 0.04% inhibition) by 10 ng/ml Bordetella pertussis toxin. In contrast to bombesin, somatostatin, 10 nM, inhibited basal InsP1, InsP2 and InsP3 formation. At 5 s, the inhibition degree for InsP3 was 18 +/- 2.5% and the IC50s values 1 +/- 0.09 nM, 1 +/- 0.12 nM and 0.07 +/- 0.005 nM for InsP1, InsP2 and InsP3, respectively. Bombesin-stimulated InsP3 formation was also inhibited by somatostatin. At 5 s, the inhibition degree was 85 +/- 3.5% at 10 nM and the IC50 value, 0.10 +/- 0.05 nM. Furthermore, somatostatin inhibition of bombesin stimulation was partly blocked (66 +/- 4% inhibition) by Bordetella pertussis toxin. These data therefore suggest that the acinar pancreatic cells contain a somatostatin receptor exerting a negative control on basal and bombesin receptor-stimulated phosphatidyl inositol turnover.
Linard
C
C
Unité de recherches de Gastroentérologie (INSERM U10), Hôpital Bichat, Paris, France.
Reyl-Desmars
F
F
Lewin
M J
MJ
D000818:Animals; D001839:Bombesin / Q000494:pharmacology*; D002478:Cells, Cultured; D004347:Drug Interactions; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism*; D008297:Male; D037342:Pertussis Toxin; D051381:Rats; D017208:Rats, Wistar; D013004:Somatostatin / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D007295:Inositol Phosphates; D010566:Virulence Factors, Bordetella; D013004:Somatostatin; D015544:Inositol 1,4,5-Trisphosphate; C066454:inositol 4,5-bisphosphate; D037342:Pertussis Toxin; D001839:Bombesin