Jfx. Jones et al., EVIDENCE THAT 5-HT1D RECEPTORS MEDIATE INHIBITION OF SYMPATHETIC GANGLIONIC TRANSMISSION IN ANESTHETIZED CATS, British Journal of Pharmacology, 116(2), 1995, pp. 1715-1717
In anaesthetized cats, 5-carboxamidotryptamine (5-CT) or 5-hydroxytryp
tamine (5-HT) (0.3-300 mu g kg(-1),i.v.) inhibited the postganglionic
compound action potential evoked by preganglionic electrical stimulati
on (0.5 Hz) with a similar potency in the stellate and splanchnic gang
lia. In the 5-HT experiments transmission thorough the inferior mesent
eric ganglia was also recorded. The maximal inhibitory effect of 5-HT
was greater on the stellate and splanchnic ganglia (60 +/- 4 and 52 +/
- 5%) than on the inferior mesenteric (15 +/- 2%). The effects of 5-HT
were unaffected by pretreatment with antagonists (1 mg kg(-1);i.v.) f
or 5-HT2 (BW501C67), 5-HT1A (WAY-100635) and 5-HT3 receptors (ondanset
ron). However, responses to both 5-HT and 5-CT were attenuated signifi
cantly by GR127935 (I mg kg(-1)) except the responses to 5-HT at the i
nferior mesenteric ganglia. These results are consistent with the invo
lvement of 5-HT1D receptors mediating inhibition of sympathetic gangli
onic transmission in vivo.