[Effect of discontinuous hemorrhage on plasma and cerebrospinal fluid vasopressin concentration in anesthesized rabbits].

Repeated withdrawal of 15 ml arterial blood at 10 min intervals produced marked hypovolaemia and hypotension with plasma vasopressin concentration increasing exponentially from 53 microE/ml to more than 700 microE/ml contrary to the hypovolaemia. After the first blood withdrawal there exists a linear correlation between the increase of the plasma vasopressin concentration and the decrease of the mean arterial blood pressure. With 61.5 microE/ml the cerebrospinal fluid withdrawn following the last bleeding likewise showed a very high vasopressin level. After extraction of the hormone from plasma and cerebrospinal fluid the vasopressin concentration was determined by means of the antidiuretic bioassay in the water-loaded rat.