Lysipressin is a pressor peptide found in marsupials and pigs that binds to VP receptors, which are analogous to human Vasopressin 2 (V2) receptors. Lysipressin induces contractions in smooth muscle and potentiates effects of gastric lesioning in animal models.
The neurohypophyseal hormones of the hippopotamus (Hippopotamus amphibius) and collared peccary (Tayassu angulatus) were isolated by molecular sieving and preparative high-pressure liquid chromatography (HPLC). Oxytocin and arginine vasopressin have been identified by their amino acid compositions and their retention times in HPLC. Lysipressin (lysine vasopressin) was not detected in posterior pituitaries of two hippopotami and nine peccaries (less than 2% of arginine vasopressin in molar ratios). Among the suborder Suiformes of Artiodactyla, the families Hippopotamidae and Tayassuidae do not seem to possess lysipressin, in contrast to the family Suidae in which the pig has lysipressin in place of arginine vasopressin.
Rouille, Y., Chauvet, M. T., Chauvet, J., Acher, R., & Hadley, M. E. (1988). The distribution of lysine vasopressin (lysipressin) in placental mammals: a reinvestigation of the Hippopotamidae (Hippopotamus amphibius) and Tayassuidae (Tayassu angulatus) families. General and comparative endocrinology, 71(3), 475-483.