Bufalin Prevents Rrestoration of Blood Volume after Hemorrhage.

Abstract

Shock is associated with cellular depolarization, a rise in extracellular K and intracellular Na, and a movement of water from the extracellular to the intracellular space. These phenomena can be explained by an inhibition of Na/K ATPase. We have found that plasma (extracts) from shocked rats inhibit Na/KATPase and increases water movement into cells. Recently, bufodienolides have been identified in mammalian plasma and are strong inhibitors of Na/K ATPase. To determine if Bufalin or Marinobufogenin (MBG) can prevent normal restoration of blood volume to mild hemorrhage, we treated awake Sprague‐Dawley rats, with either 1) 20ml/kg hemorrhage, 2) an infusion of Bufalin or MBG, or 3) both (n=>8 all groups). Hemorrhage led to an immediate fall in plasma volume followed by recovery to normal by 60min. However, rats given bufalin and non‐lethal hemorrhage failed to restore blood volume and died within 60min. Bufalin alone led to no significant change in blood volume. Marinobufogenin, given at this dose and higher did not prevent restoration of blood volume. These data suggest that Bufalin but not MBG, prevents normal restoration of blood volume after hemorrhage.