Immunohistochemical Localization of Vasoactive Intestinal Peptide in the Dogfish Rectal Gland

Vasoactive intestinal peptide (VIP) has been shown to increase chloride secretion from the rectal gland of the spiny dogfish, Squalus acanthias , by a cyclic AMP-mediated Na super(+), K super(+)-ATPase mechanism. VIP-stimulated chloride ion secretion is completely inhibited by somatostatin. Localization of the peptides that affect chloride secretion in the dogfish rectal gland is not known. The authors have studied by immunohistochemistry the localization of immunoreactive VIP (IR-VIP) and immunoreactive somatostatin (IR-SS) in this model system of ion transport.