Extensive skinning of cell membrane diminishes the force-inhibiting effect of okadaic acid on smooth muscles of guinea pig hepatic portal vein

The influences of cell membrane permeabilization (skinning) on the okadaic acid-induced inhibition of vascular smooth muscle contraction were studied in guinea pig hepatic portal vein. Pretreatment by 1 muM okadaic acid in the absence of Ca2+ suppressed subsequent submaximal Ca2+-induced contraction in preparations permeabilized with Staphylococcus aureus alpha-toxin or beta-escin, but not in those treated with saponin or Triton X-100. The SDS-PAGE of elutants from the preparation suggests that the loss of the inhibitory effect of okadaic acid in preparations skinned with saponin or Triton X-100 results from the leakage of some cellular components with a molecular mass of 67 to 200 kDa.