The factors that regulate vasopressin secretion have been clearly defined (Fig. 5.9), the major determinant being plasma osmolality. Different solutes, however, have varying abilities to stimulate vasopressin release. Sodium and mannitol appear to be the most potent solutes, while glucose has little or no effect on vasopressin secretion. Large quantities of vasopressin are released after marked hypotension, hypovolaemia, and vomiting. Angiotensin II and hypoglycaemia both appear to be specific stimuli of vasopressin secretion. Although many other factors have been reported to stimulate vasopressin release (e.g. pain, stress, profound emotion), it remains controversial whether vasopressin is a true stress hormone.
