5-HT activates neural reflexes regulating secretion in the guinea-pig colon.
The role of 5-hydroxytryptamine (5-HT) in neural reflexes regulating secretion was examined in muscle-stripped segments of guinea-pig colon set up in modified flux chambers. A 15-microL pulse of 5-HT (100 microM) to the mucosal bath (1.5 mL), which was continuously perfused, evoked an increase in short-circuit current (Isc). The 5-HT-induced increase in Isc was inhibited by tetrodotoxin, N-acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide (5-HTP-DP), GR82334 and atropine, but not by tropisetron. 5-HTP-DP reduced the response to a 5-HT pulse over the concentration range of 1 nM to 1 microM. The Isc response to a 5-HT pulse was unaffected by the cyclooxygenase inhibitor, piroxicam. This contrasted with a reduction in the Isc response to mucosal stroking with a brush by piroxicam. The results suggest that a 5-HT pulse, like mucosal stroking, activates a secretory reflex that includes tachykinin and cholinergic neurons but, unlike mucosal stroking, does not release prostaglandins.
Cooke
H J
HJ
Department of Pharmacology, Ohio State University, Columbus 43210, USA.
Sidhu
M
M
Wang
Y Z
YZ
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism; D003106:Colon / Q000294:innervation* / Q000502:physiology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000294:innervation / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000502:physiology*; D010275:Parasympathetic Nervous System / Q000502:physiology; D010894:Piroxicam / Q000494:pharmacology; D011453:Prostaglandins / Q000378:metabolism; D012018:Reflex / Q000502:physiology; D012701:Serotonin / Q000502:physiology*; D009435:Synaptic Transmission; D015320:Tachykinins / Q000502:physiology
D000894:Anti-Inflammatory Agents, Non-Steroidal; D002712:Chlorides; D011453:Prostaglandins; D015320:Tachykinins; D010894:Piroxicam; D012701:Serotonin