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F M Correa

Publications and source records attributed to F M Correa.

49 records · Page 3Linked to original sources
PubMedDate not supplied

Quantitative distribution of angiotensin II binding sites in rat brain by autoradiography.

Angiotensin II binding sites were localized and quantified in individual brain nuclei from single rats by incubation of tissue sections with 1 nM 125I-[Sar1]-angiotensin II, [3H]-Ultrofilm autoradiography, computerized microdensitometry and comparison with 125I-standards. High angiotensin II binding was present in the circumventricular organs (organon vasculosum laminae terminalis, organon subfornicalis and area postrema), in selected hypothalamic nuclei (nuclei suprachiasmatis, periventricularis and paraventricularis) and in the nucleus tractus olfactorii lateralis, the nucleus preopticus medianus, the dorsal motor nucleus of the vagus and the nucleus tractus solitarii. High affinity (KA from 0.3 to 1.5 X 10(9) M-1) angiotensin II binding sites were demonstrated in the organon subfornicalis, the nucleus tractus solitarii and the area postrema after incubation of consecutive sections from single rat brains with 125I-[Sar1]-angiotensin II in concentrations from 100 pM to 5 nM. These results demonstrate and characterize brain binding sites for angiotensin II of variable high affinity binding both inside and outside the blood-brain barrier.

Angiotensin II↗
PubMedDate not supplied

Binding of angiotensin and atrial natriuretic peptide in brain of hypertensive rats.

Atrial natriuretic peptides, produced in the mammalian cardiac atrium, are released into the general circulation and may be actively involved in the control of blood pressure and in fluid homeostasis as antagonists of the peripheral angiotensin system. Certain cardiovascular effects of atrial natriuretic peptides may be centrally mediated, as binding sites for atrial natriuretic factor (8-33) (ANF) have been localized to the subfornical organ. This circumventricular structure lacks a blood-brain barrier and is therefore accessible to circulating peptides. It contains large numbers of angiotensin II (AII) binding sites, and has been suggested as the main central site of action for circulating AII in the regulation of blood pressure and fluid metabolism. Here we have studied binding sites for rat atrial natriuretic peptide(6-33) (rANP) and AII in the brains of spontaneously (genetic) hypertensive rats (SHR) and their normotensive controls, Wistar Kyoto (WKY) rats, by quantitative autoradiography. Binding sites for both peptides were highly localized in the subfornical organ. The number of rANP binding sites was decreased in the subfornical organ of both young (4 weeks old) and adult (14 weeks old) SHR compared with age-matched normotensive controls. Conversely, the number of AII binding sites was higher in both young and adult SHR compared with WKY rats. Our results suggest a central role for rANP and AII in genetic hypertension; they may act as mutual antagonists in brain areas involved in control of blood pressure and fluid regulation.

Age Factors↗