TY - JOUR
T1 - Multiple 5-hydroxytryptamine receptors on feline ileum and ileocecal sphincter
AU - Ouyang, A.
AU - Cohen, S.
PY - 1983
Y1 - 1983
N2 - The effects of 5-hydroxytryptamine (5-HT) on the feline ileum and ileocecal sphincter (ICS) were studied in vivo using simultaneous myoelectric and pressure recordings. Both inhibitory and excitatory responses were seen in the ileum and ICS, with the inhibitory response being seen with lower doses of 5-HT [ED(max) for inhibition was 5.0 μg/kg and ED(max) for contractile response was 80.0 μg/kg]. The inhibitory and excitatory responses were antagonized separately by different 5-HT antagonists. Methysergide inhibited the ICS relaxation response only, whereas cinanserin inhibited the ICS contractile response. Neither effect was inhibited by tetrodotoxin, suggesting that 5-HT acts directly on the smooth muscle at at least two separate receptors. In addition, methysergide alone resulted in a usually tonic increase (8.6 ± 0.6 mm Hg) in basal ICS pressure (P < 0.05) without an ileal effect, and tetrodotoxin alone induced phasic ileal and ICS contractions (ΔICS = 7.3 ± 1.5 mm Hg). These data suggest the action of at least two inhibitory neurons tonically at the ICS.
AB - The effects of 5-hydroxytryptamine (5-HT) on the feline ileum and ileocecal sphincter (ICS) were studied in vivo using simultaneous myoelectric and pressure recordings. Both inhibitory and excitatory responses were seen in the ileum and ICS, with the inhibitory response being seen with lower doses of 5-HT [ED(max) for inhibition was 5.0 μg/kg and ED(max) for contractile response was 80.0 μg/kg]. The inhibitory and excitatory responses were antagonized separately by different 5-HT antagonists. Methysergide inhibited the ICS relaxation response only, whereas cinanserin inhibited the ICS contractile response. Neither effect was inhibited by tetrodotoxin, suggesting that 5-HT acts directly on the smooth muscle at at least two separate receptors. In addition, methysergide alone resulted in a usually tonic increase (8.6 ± 0.6 mm Hg) in basal ICS pressure (P < 0.05) without an ileal effect, and tetrodotoxin alone induced phasic ileal and ICS contractions (ΔICS = 7.3 ± 1.5 mm Hg). These data suggest the action of at least two inhibitory neurons tonically at the ICS.
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U2 - 10.1152/ajpgi.1983.244.4.g426
DO - 10.1152/ajpgi.1983.244.4.g426
M3 - Article
C2 - 6837748
AN - SCOPUS:0020743647
SN - 0193-1857
VL - 7
SP - G426-G434
JO - American Journal of Physiology - Gastrointestinal and Liver Physiology
JF - American Journal of Physiology - Gastrointestinal and Liver Physiology
IS - 4
ER -