Comparison of the biological activity of canine and porcine motilin in rabbit

• Published in: Regulatory peptides Vol. 15; no. 4; p. 333
• Main Authors: Peeters, T L, Bormans, V, Matthijs, G, Vantrappen, G
• Format: Journal Article
• Language: English
• Published: Netherlands 01-11-1986
• Subjects: Acetylcholine - pharmacology; Animals; Dogs; Dose-Response Relationship, Drug; Duodenum - metabolism; Duodenum - physiology; In Vitro Techniques; Motilin - metabolism; Motilin - pharmacology; Muscle Contraction - drug effects; Muscle, Smooth - drug effects; Muscle, Smooth - metabolism; Muscle, Smooth - physiology; Rats; Receptors, Gastrointestinal Hormone - metabolism; Receptors, Neuropeptide; Species Specificity; Swine
• ISSN: 0167-0115
• DOI: 10.1016/0167-0115(86)90163-1

The biological activity of porcine and canine motilin was studied in rabbits by establishing dose-response curves of both peptides using two different methods. The dissociation constant, obtained from the displacement of iodinated porcine motilin by canine motilin was 0.6 +/- 0.3 nM, versus 1.2 +/- 0.4 nM for porcine motilin. For the 13-norleucine and 13-leucine analogues of porcine motilin a value of 0.8 +/- 0.3 nM was obtained. Both motilins were almost equipotent in stimulating the in vitro contractile response of longitudinal smooth muscle strips: half-maximal effect was achieved at a concentration of 1.0 +/- 0.1 nM for canine versus 1.3 +/- 0.2 nM for the 13-norleucine analogue of porcine motilin. We conclude that porcine and canine motilin have a comparable bioactivity in the rabbit, although canine motilin is slightly more effective. The motilin receptor is probably specific for the N-terminal portion which is identical in both molecules.