Long-term and constant release of vasopressin from Accurel tubing: implantation in the Brattleboro rat.

A long-lasting and constant release of vasopressin in serum solution (in vitro) for periods up to 50 days can be obtained by the use of small-diameter microporous Accurel polypropylene tubing, filled with vasopressin and covered with collodion. The potency of the preparation is shown in vivo after subcutaneous implantation in the adult vasopressin-deficient Brattleboro rat, for which normal levels of urine production and osmolality were achieved at least for 1 month. The possible use of this method for other peptides and its application in small or immature laboratory animals and in fetuses is emphasized.