Vasopressin Regulation and Potassium Homeostasis Following Recovery from Severe Blood loss in a Conscious Rat Model of Hemorrhagic Shock

In an anesthetized, mechanically ventilated pig model, we have found that non-survival in the first minutes after severe hemorrhage is associated with a rapid elevation in plasma potassium (K) and a blunted endogenous vasopressin(VP) response in non-survivors compared to survivors. We have also shown that exogenously administered VP during hemorrhage resuscitation causes a dramatic increase in urine flow and can increase the fractional excretion of K compared to other pressor agents. Thus, early survival of acute rapid blood loss in severe hemorrhage may depend on the ability of VP to regulate renal normalization of circulating plasma K levels. It is unknown what may prevent an adequate endogenous VP response that would allow renal K excretion to be maintained in the face of low urine output during hemorrhage-induced hypotensive shock. Aside from responding only to hypotension and hyperkalemia, other factors of electrolyte or acid-base balance may also affect VP regulation of K balance. Thus, in this stud...