[Excitant effect of sodium suberogorgin on isolated rabbit ileum]

Suberogorgin was isolated from Gorgoniae suberogorgia sp from South China Sea. The isolated rabbit ileum contracted in a concentration-dependent manner by suberogorgin-Na (Sub) 2.13 mumol.L-1 or higher. Sub 213 mumol.L-1 had no effect on the relaxation induced by norepinephrine and isoprenaline 10-100 mumol.L-1 on ileum. The stimulation of Sub on ileum was antagonized by atropine 56 mumol.L-1 or indometacin 0.35 mmol.L-1 and was partly blocked by indometacin 0.17 mmol.L-1, but was not affected by diphenhydramine 10 mumol.L-1. On the contracted ileum induced by neostigmine 1.7 mumol.L-1, acetylcholine 0.1 mumol.L-1 increased the tension but Sub 213 mumolL-1 did not. Sub obviously inhibited the acetylcholinesterase (AChE) from mouse brain hemogenates in vitro. Its pI50 (negative logarithm of molar concentration causing 50% inhibition of AChE) was 4.18, while the pI50 of neostigmine was 4.75. The results indicated that the ileum-excitant action of Sub was chiefly related to the inhibition of AChE.