Characterization of angiotensin II receptors in the anterior pituitary gland.
Specific and high affinity binding sites for angiotensin II were demonstrated in the anterior pituitary gland by binding studies with [125I] iodoangiotensin II. The binding properties of the pituitary receptors were similar to those of angiotensin II receptors present in the adrenal gland. The concentration of binding sites in rat anterior pituitary (293 +/- 50 fmoles/mg protein) was less than in the adrenal gland, but was much greater than in smooth muscle. Angiotensin II receptors were identified in the anterior pituitary tissue of mature and immature animals of both sexes, and in species including rat, rabbit and dog. No binding of angiotensin II was detected in posterior pituitary homogenates, or in GH3 pituitary tumor cells. Collagenase-dispersed anterior pituitary cells also contained specific binding sites for angiotensin II, with equilibrium binding constant (Ka) of 3.6 x 10(9) M-1. The presence of specific high-affinity angiotensin II receptor in the anterior pituitary gland provides a mechanism by which angiotensin-like peptides could modulate the process of pituitary hormone secretion.
D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D004285:Dogs; D005260:Female; D008297:Male; D010903:Pituitary Gland, Anterior / Q000032:analysis* / Q000166:cytology; D010904:Pituitary Gland, Posterior / Q000032:analysis; D010908:Pituitary Hormones, Anterior / Q000378:metabolism; D011817:Rabbits; D011869:Radioligand Assay / Q000379:methods; D051381:Rats; D011945:Receptors, Angiotensin / Q000032:analysis*; D011956:Receptors, Cell Surface / Q000032:analysis*; D013997:Time Factors
D010908:Pituitary Hormones, Anterior; D011945:Receptors, Angiotensin; D011956:Receptors, Cell Surface; D000804:Angiotensin II