Table 1

Stereoselective effects of cannabinoids on electrically evoked contractions of guinea pig isolated ileum or of the myenteric plexus-longitudinal muscle preparation (MPLM) of guinea pig ileum

Procedure Cannabinoid Concentration Effect on twitch amplitude Ref
Supramaximal stimulation of whole ileum at 0.1 Hz (ethanol)(–)-Δ8-THC79.5 nMInhibition9
(+)-Δ8-THC318nMNone
(–)-11-OH-Δ9-THCca. 3 nM upwardsInhibition
(+)-11-OH-Δ9-THC61 nMNone
Stimulation of whole ileum at 0.1 Hz (ethanol)(–)-Δ9-THC 1-150EC50=100 nMInhibition10
(+)-Δ9-THC2 μMNone
Supramaximal stimulation of MPLM at 0.2 Hz (Cremophor EL)(–)-Δ9-THC 1-150EC50=125 nMInhibition11
(+)-Δ9-THC 1-150EC50=3.1 μMInhibition
Supramaximal stimulation of MPLM at 0.1 Hz (Tween 80)HU-210 1-150EC50=1.4 nMInhibition12
HU-211 1-150EC50 >316 nMInhibition (316 nM)
Supramaximal stimulation of MPLM at 0.1 Hz (Tween 80)CP559401-151 1-150EC50=3.5 nMInhibition13
CP56667 1-150EC50=162.9 nMInhibition
Supramaximal stimulation of MPLM at 0.1 Hz (Tween 80)(+)-WIN55212EC50=5.5 nMInhibition13 14
(–)-WIN552121 μMNegligible

  • ↵1-150 Concentration producing 50% inhibition of the twitch response. Cannabinoid vehicle used is shown in paraentheses.

  • ↵1-151 CP55940 has also been found to be more potent than CP56667 as a twitch inhibitor of mouse MPLM.15

  • CP56667 is the (+)-enantiomer of CP55940 and HU-211 is the (+)-enantiomer of HU-210 (dimethylheptyl-11-hydroxy-Δ8-tetrahydrocannabinol).

  • The samples of (+)-Δ8-THC and (+)-Δ9-THC used probably contained 5–10% of the corresponding (−)-enantiomer.16