Guanidine derivative U-37883A, inhibits mitochondrial K+ uniport

The activity of potassium uniport in rat liver mitochondria was measured using light scattering technique (mitochondrial swelling). It was shown, that guanidine derivative, U-37883A (4-morpholinecarboxamidine-N-1-adamantyl-N'-cyclohexylhyd rochloride), was able to inhibit A23187 induced potassium uniport activity. The inhibitory effect of U-37883A on mitochondrial swelling gave an IC50 an of 89 +/- microM. No inhibition was observed with U-37883A analog, U-42069D (4-morpholinecarboxamidine), which points to the specificity of U-37883A action. It was also shown, that U-37883A acted on a different binding site in rat liver mitochondria than glibenclamide, inhibitor of the ATP sensitive potassium channel.