Rat and guinea pig pancreatic acini possess both VIP1 and VIP2 receptors, which mediate enzyme secretion
In: American journal of physiology. Gastrointestinal and liver physiology, Jg. 41 (2000), Heft 1, S. G64- (11S.)
Online
academicJournal
- print, 38 ref
Zugriff:
Pancreatic acini from most species possess vasoactive intestinal peptide (VIP) receptors. Recently, two subtypes of VIP receptors, VIP1-R and VIP2-R, were cloned. Which subtype exists on pancreatic acini or mediates secretion is unclear. To address this, we examined pancreatic acini from both rat and guinea pig. VIP1-R and VIP2-R mRNA were identified in dispersed acini from both species by Northern blot analysis and in rat by Southern blot analysis. With the use of the VIP2-R-selective ligand Ro-25-1553 in both species, inhibition of binding of 125 I-labeled VIP to acini showed a biphasic pattern with a high-affinity component (10%) and a second representing 90%. The VIP1-R-selective ligand, [Lys15,Arg16,Leu27]VIP-(1-7)-GRF-(8-27), gave a monophasic pattern. Binding of Ro-25-1553 was better fit by a two-site model. In both rat and guinea pig acini, the dose-response curve of Ro-25-1553 for stimulation of enzyme secretion was biphasic, with a high-affinity component of 10-15% of the maximal secretion and a low-affinity component accounting for 85-90%. At low concentrations (10 nM) of Ro-25-1553 and [Lys15,Arg16,Leu27]VIP-(1-7)-GRF(8-27), which only occupy VIP receptors, a 4-fold and a 56-fold increase in cAMP occurred, respectively. These results show that both VIP1-R and VIP2-R subtypes exist on pancreatic acini of rat and guinea pig, their activation stimulates enzyme secretion by a cAMP-mediated mechanism, and the effects of VIP are mediated 90% by activation of VIP1-R and 10% by VIP2-R. Because VIP has a high affinity for both VIP-R subtypes, its effect on pancreatic acini is mediated by two receptor subtypes, which will need to be considered in future studies of the action of VIP in the pancreas.
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Rat and guinea pig pancreatic acini possess both VIP1 and VIP2 receptors, which mediate enzyme secretion
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Autor/in / Beteiligte Person: | ITO, T ; HOU, W ; KATSUNO, T ; IGARASHI, H ; PRADHAN, T. K ; MANTEY, S. A ; COY, D. H ; JENSEN, R. T |
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Zeitschrift: | American journal of physiology. Gastrointestinal and liver physiology, Jg. 41 (2000), Heft 1, S. G64- (11S.) |
Veröffentlichung: | Bethesda, MD: American Physiological Society, 2000 |
Medientyp: | academicJournal |
Umfang: | print, 38 ref |
ISSN: | 0193-1857 (print) |
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