Decreased angiotensin II binding affinity and binding capacity in the anterior pituitary gland of adult spontaneously hypertensive rats.
Angiotensin II (ANG) binding sites were quantified in single pituitary glands from 4-week-old and 14-week-old male spontaneously hypertensive rats (SHR) and age-matched male normotensive Wistar-Kyoto (WKY) control rats after incubation with 125I-[Sar1]-ANG, autoradiography with computerized densitometry, and comparison to 125I-standards. The maximum binding capacity (Bmax) decreased while the dissociation constant (Kd) for ANG increased in 14-week-old SHR when compared to age-matched WKY control rats (Bmax: 265 +/- 9 and 224 +/- 4 fmol/mg protein; Kd: 0.79 +/- 0.04 and 1.14 +/- 0.08 10(-9) M in WKY and SHR, respectively). Conversely, no difference between rat strains was found in 4-week-old animals. Our results suggest that pituitary ANG binding sites may play a role in the pathophysiology of established genetic hypertension.
Gutkind
J S
JS
Unit on Preclinical Neuropharmacology, National Institute of Mental Health, Bethesda, Maryland 20892.
Castrén
E
E
Saavedra
J M
JM
D000375:Aging / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D006973:Hypertension / Q000378:metabolism*; D008297:Male; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D011945:Receptors, Angiotensin / Q000378:metabolism*
D011945:Receptors, Angiotensin