SUPPRESSION OF INTESTINAL SMOOTH-MUSCLE CONTRACTION BY 4-ETHYLGUAIACOL, A CONSTITUENT OF WOOD CREOSOTE

Wood creosote, a mixture of phenolic compounds, suppresses in vitro co ntractions of rat intestine. To identify a compound in wood creosote a ble to inhibit intestinal motility, we screened its constituent phenol ic compounds and found 4-ethylguaiacol (4-EG) as an active compound. I t suppressed the spontaneous phasic (IC50 = 513 +/- 48 mumol/l) as wel l as spasmogenic-agent-induced tonic longitudinal contractions of isol ated rat ileum in a reversible and concentration-dependent manner. KCl -depolarization-induced tonic contraction, which was susceptible to a calcium channel blocking agent, was also suppressed by 4-EG with an IC 50 of 433 +/- 41 mumol/l. Furthermore, calcium-ionophore-induced contr action, which was affected by an influx of extracellular calcium ion t hat bypassed calcium channels, was suppressed by 4-EG with an IC50 of 97 +/- 18 mumol/l. These results support the concept that the effect o f wood creosote to suppress intestinal motility is attributable, parti ally or entirely, to its component 4-EG and that this effect of 4-EG o n the intestinal muscle is produced at some stage(s) of the muscle con traction process after influx of extracellular calcium into the cytoso l of smooth muscle.