[Contribution to the study of labeled neurohypophysial hormones. Preliminary data on the properties of the macromolecular compound: vasopressin-dextran (author's transl)].
The neuropeptide binding sites at the level of their target cells can be localized by several morphological methods. For one of the neurohypophysial hormones, vasopressin, not all labelling techniques can be applied: radioiodinated vasopressin has no biological activity; only 3Hvasopressin can be used. Immunocytochemical evidence for vasopressin receptors must be supported by complementary data in order to demonstrate the specificity of the binding. A new labelled ligand is prepared: vasopressin-dextran. In vivo, this macromolecular compound has antidiuretic properties equivalent to those of free vasopressin. In vitro, it gives a cross reaction with specific anti-vasopressin antibodies. For the same macromolecular compound, the ratio between the conjugated vasopressin estimated through R.I.A. and that assayed by biological method was 30.