Autoinhibition and desensitization of serotonergic responses in guinea pig ileum.
The present study was undertaken to investigate the autoinhibition and desensitization of 5-hydroxytryptamine (5-HT) using another agonist MK-212 on guinea pig ileum. 5-HT and MK-212 produced dose dependent contractions of guinea pig ileum. The responses to MK-212 were reduced in the presence of 5-HT and vice versa. Neither 5-HT nor MK-212 produced any change in the responses to histamine, acetylcholine or KCl. Increase in Ca++ in bathing fluid reversed the desensitization produced by MK-212 or 5-HT. Our data suggest that 5-HT and MK-212 produce desensitization which is specific for serotonergic receptors and possibly involves Ca++ ions.
Chinmayee
N
N
Department of Pharmacology, L. M. College of Pharmacy, Navrangpura, Ahmedabad.
Joshi
D P
DP
Mehta
A A
AA
Goyal
R K
RK
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004351:Drug Resistance; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D011719:Pyrazines / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology*; D013329:Structure-Activity Relationship
D011719:Pyrazines; D012701:Serotonin; C014896:6-chloro-2-(1-piperazinyl)pyrazine; D002118:Calcium