Effect of inhalation anesthetics on swimming activity of artemia salina.

The swimming movement of artemia salina in the artificial sea water was measured by using the video camera system in the absence and presence of anesthetics, i.e. enflurane, halothane, and isoflurane. The movement of artemia looked random at a glance but the obtained distribution curve for the swimming speed was skewed toward the high speed side somewhat resembling a Maxwellian distribution curve seen in the statistics of ideal gases. When anesthetic were added, the distribution curve became sharpened and shifted to the low speed side, which is similar to a behavior of ideal gases when they are cooled down. The mean swimming-speed was decreased eventually leading to an irreversible death with increasing the anesthetic dose. The activity was analyzed by using the hydrodynamic equation. The ED(50), which is a dose that causes a 50% reduction in the activity, of all anesthetics used in this study was quite similar to the MAC values for human. It was also suggested that an interaction between anesthetics and artemia was highly cooperative since the larger Hill coefficients were obtained for all three anesthetics used.