RSN preservation vs. immobilization. (IMAGE) Tokyo Metropolitan University Caption Better RSN preservation is seen when the animal is not strongly immobilized. The team concludes that Mida or Dex with light restraints is optimal. If restraints are not feasible, then IsoDex or Propo is recommended. Alfa, Iso and Sevo do not preserve the RSN. Credit Tokyo Metropolitan University Usage Restrictions Please give credit for use. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.