Effects of ethanol and acetaldehyde on the contraction of cultured Ito cells

The effects of ethanol (Et-OH) and acetaldehyde (Ac-CHO) on the contraction of cultured Ito cells were studied using a time-interval videotape recorder (VTR). Ito cells were isolated from Wistar rats and cultured for 4 days. The motion of the cells was recorded by VTR and the sequential changes of the surface area of the each cell were evaluated by an image analyzer. No contraction of Ito cells was observed after incubation with Et-OH (100 mM) or Ac-CHO (500 microM) alone. Ten nanomoles endothelin-1 (ET-1) caused Ito cells to contract gradually. Pre-incubation of ET-1 with Ac-CHO at 37 degrees C for 1 hr inhibited the contraction of Ito cells completely. This inhibition was not seen in pre-incubation of ET-1 with Et-OH. In addition, the Ito cells which were pre-cultured with Ac-CHO for 6 hr did not contract at all after incubation with ET-1. In the isoelectric focusing of ET-1, a band was clearly seen at pI 4.6 after the treatment with Et-OH as well as non-treated ET-1. Two extra bands of ET-1 appeared in the anodic side of the gel after treatment with Ac-CHO, indicating the conformational changes of ET-1. These results indicated that the contraction of Ito cells induced by ET-1 was inhibited completely by Ac-CHO. This inhibitory effect of Ac-CHO was thought to be caused by binding Ac-CHO to ET-1 itself or to ET-1 receptors.