Brief Reports
Copyright ©2005 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 7, 2005; 11(21): 3264-3266
Published online Jun 7, 2005. doi: 10.3748/wjg.v11.i21.3264
Interplay between nitric oxide and VIP in CCK-8-induced phasic contractile activity in the rabbit sphincter of Oddi
Attila Pálvölgyi, Réka Sári, József Németh, Annamária Szabolcs, István Nagy, Péter Hegyi, János Lonovics, Zoltán Szilvássy
Attila Pálvölgyi, Réka Sári, Annamária Szabolcs, István Nagy, Péter Hegyi, János Lonovics, First Department of Medicine, Faculty of Medicine, University of Szeged, H-6720 Szeged, Korányi fasor 8-10, Hungary
József Németh, Department of Pharmacology, Medical University of Pécs, H-7643 Pécs, Szigeti u. 12, Hungary
Zoltán Szilvássy, Department of Pharmacology, Medical University of Debrecen, H-4032 Debrecen, Nagyerdei krt. 98, Hungary
Author contributions: All authors contributed equally to the work.
Correspondence to: Réka Sári PhD, First Department of Medicine, University of Szeged, H-6701, PO Box 469, Hungary. sari@in1st.szote.u-szeged.hu
Telephone: +36-62-545200 Fax: +36-62-545185
Received: June 16, 2004
Revised: June 18, 2004
Accepted: July 27, 2004
Published online: June 7, 2005
Abstract

AIM: The sphincter of Oddi (SO) plays an important role in delivery of bile into the duodenum. To establish whether vasoactive intestinal polypeptide (VIP) and nitric oxide (NO) were involved in phasic contractile activity of the rabbit SO stimulated by cholecystokinin-octapeptide (CCK-8).

METHODS: Isolated SO muscle rings were cleaned of fat and mounted horizontally on two small L-shaped hooks one of which was connected to a force transducer for the measurement of isometric tension. The experiments were carried out in a thermostatically controlled (37±0.2 °C) organ bath (5 mL) containing Krebs solution. The organ fluid was gassed with 95% O2 and 50 mL/L CO2 to keep the pH at 7.40±0.05. Contractile responses to CCK-8 (1 μmol/L) were evaluated in the presence and absence of NG-nitro-L-arginine (LNNA), an inhibitor of NO synthase (100 μmol/L), and (p-chloro-D-Phe6-Leu17)-VIP (VIPa, 30 μmol/L), a VIP receptor antagonist.

RESULTS: CCK-8 stimulated the phasic activity of the SO. NO synthase inhibition increased the frequency and amplitude of contractions with a slight increase in developed tension. Pre-incubation with VIPa also attenuated this CCK-8 effect. The combined application of LNNA and VIPa abolished the phasic activity of the muscle rings with a marked increase in tension in response to CCK-8.

CONCLUSION: VIP and NO together contribute to an increase in phasic activity of SO.

Keywords: Sphincter of Oddi; CCK; VIP; NO; LNNA