Capric acid as a potent dilator of canine vessels in vitro and in vivo.

1. Pharmacodynamic effects of even numbered saturated fatty acids, C4-C16, were determined on isolated canine basilar and femoral arteries precontracted with PGF2 alpha. 2. The fatty acids relaxed the precontracted vessels. 3. The basilar artery was the most sensitive vessel and caprate (C10) was the most potent acid with an EC50 of 49 microM. 4. The relaxant effect was endothelium-independent. 5. Contractions elicited by norepinephrine, serotonin, and U46619 were also inhibited. 6. Caprate (C10) given intra-arterially increased femoral blood flow in a dose-dependent manner and the dose computed to increase blood flow 50% was 1.27 microM/kg.