The drug Vaprisol is an antagonist for this hormone, as are the Vaptan class of drugs and Democlocycline.  The syndrome of inappropriate this hormone is a common paraneoplastic effect of small cell lung cancer. This hormone triggers the phosphatidylinositol pathway throught V1 receptors in certain smooth muscle tissues.  Angiotension II acts to release both Aldosterone and this hormone.  This hormone differs from Oxytocin at only two amino acid residues, and its deficiency is the most common cause for Diabetes insipidus.  The major function of 
The drug Vaprisol is an antagonist for this hormone, as are the Vaptan class of drugs and Democlocycline.  The syndrome of inappropriate this hormone is a common paraneoplastic effect of small cell lung cancer. This hormone triggers the phosphatidylinositol pathway throught V1 receptors in certain smooth muscle tissues.  Angiotension II acts to release both Aldosterone and this hormone.  This hormone differs from Oxytocin at only two amino acid residues, and its deficiency is the most common cause for Diabetes insipidus.  The major function of this hormone is to open aquaporins in the distal convoluted tubule and collecting ducts of the kidneys.  For 10 points, name this nine-peptide hormone that causes reduced urine volume.
The drug Vaprisol is an antagonist for this hormone, as are the Vaptan class of drugs and Democlocycline.  
Arginine Vasopressin [accept AVP, accept Anti-Diuretic Hormone or ADH, do not accept "Lysine Vasopressin" or "Lysopressin"]