A possible role of the brain angiotensin II receptor binding in development of hypertension.

To clarify a role of brain angiotensin II receptor binding in development of hypertension, the regional distribution and extent of specific angiotensin II binding were studied in salt-loaded normotensive (NTR) and spontaneously hypertensive (SHR) rats, and Goldblatt one-kidney hypertensive rat (GB). Further, angiotensin-converting enzyme activity was measured in these rats' brains. In control rats, angiotensin Ii receptor binding was consistently lower in the thalamus, hypothalamus, midbrain, striatum and cortex of SHR rats than in NTR rats. In GB rats, the binding capacity in the thalamus was greater than that of NTR rats. Sodium intake resulted in a rise in the receptor binding capacity in the hypothalamus, thalamus and striatum of SHR rat, whereas it did in a fall in the binding capacity in the hypothalamus, thalamus, striatum, midbrain and cortex of NTR rats. Angiotensin-converting enzyme activity was significantly elevated in the midbrain of salt-loaded SHR rats.