Mechanisms for modulation of mouse gastrointestinal motility by proteinase-activated receptor (PAR)-1 and -2 in vitro.
Proteinase-activated receptor (PAR)-1 or -2 modulates gastrointestinal transit in vivo. To clarify the underlying mechanisms, we characterized contraction/relaxation caused by TFLLR-NH2 and SLIGRL-NH2, PAR-1- and -2-activating peptides, respectively, in gastric and small intestinal (duodenal, jejunal and ileal) smooth muscle isolated from wild-type and PAR-2-knockout mice. Either SLIGRL-NH2 or TFLLR-NH2 caused both relaxation and contraction in the gastrointestinal preparations from wild-type animals. Apamin, a K+ channel inhibitor, tended to enhance the peptide-evoked contraction in some of the gastrointestinal preparations, whereas it inhibited relaxation responses to either peptide completely in the stomach, but only partially in the small intestine. Indomethacin reduced the contraction caused by SLIGRL-NH2 or TFLLR-NH2 in both gastric and ileal preparations, but unaffected apamin-insensitive relaxant effect of either peptide in ileal preparations. Repeated treatment with capsaicin suppressed the contractile effect of either peptide in the stomach, but not clearly in the ileum, whereas it enhanced the apamin-insensitive relaxant effect in ileal preparations. In any gastrointestinal preparations from PAR-2-knockout mice, SLIGRL-NH2 produced no responses. Thus, the inhibitory component in tension modulation by PAR-1 and -2 involves both apamin-sensitive and -insensitive mechanisms in the small intestine, but is predominantly attributable to the former mechanism in the stomach. The excitatory component in the PAR-1 and -2 modulation may be mediated, in part, by activation of capsaicin-sensitive sensory nerves and/or endogenous prostaglandin formation. Our study thus clarifies the multiple mechanisms for gastrointestinal motility modulation by PAR-1 and -2, and also provides ultimate evidence for involvement of PAR-2.
Sekiguchi
Fumiko
F
Division of Physiology and Pathophysiology, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan.
Hasegawa
Naomi
N
Inoshita
Keiko
K
Yonezawa
Daiki
D
Inoi
Naoki
N
Kanke
Toru
T
Saito
Naohiro
N
Kawabata
Atsufumi
A
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D001030:Apamin / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects*; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007422:Intestines / Q000187:drug effects; D007537:Isometric Contraction / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009126:Muscle Relaxation / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects; D009842:Oligopeptides / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D011453:Prostaglandins / Q000494:pharmacology; D044463:Receptor, PAR-1 / Q000819:agonists / Q000187:drug effects*; D044464:Receptor, PAR-2 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000187:drug effects*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013270:Stomach / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors
D000894:Anti-Inflammatory Agents, Non-Steroidal; D002121:Calcium Channel Blockers; D009842:Oligopeptides; C462999:PAR-1-activating peptide; D015221:Potassium Channels; D011453:Prostaglandins; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D001030:Apamin; D002211:Capsaicin; D007213:Indomethacin; D010975:Platelet Aggregation Inhibitors