Comparison of antispasmodic effect of synthetic lysolecithins with various fatty acid moieties on guinea pig ileum

Non-competitive antispasmodic effects of 8 kinds of synthetic L-alpha-lysolecithins (1-O-acyl-2-lyso-sn-glycero-3-phosphocholine, LPC) with various fatty acid moieties were examined upon the spasmodic actions of histamine and acetylcholine on guinea pig ileum. Five-min pretreatment of the gut with the synthetic LPC was required to be effective. With increase of the concentration of a synthetic LPC for pretreatment of the ileum, the slope of the dose-response curve of histamine or acetylcholine added cumulatively became more gentle, the maximal contraction was suppressed apparently, and which were associated with the shift of the curve to the higher concentration of the stimulants. Of LPCs with saturated fatty acid palmitoyl-LPC showed the strongest effect, followed by myristoyl-, stearoyl-, lauroyl- and decanoyl-LPCs in order. Incorporation of cis-double bond into the C18 fatty acid chain of LPC resulted in slight decrease of the antispasmodic effect. The relaxating effect of LPCs on perfused rabbit ear vessel preparations was similar in order.