1. Rats genetically sensitive to salt-induced hypertension showed higher levels of plasma noradrenaline and adrenaline than rats genetically resistant to hypertension.
2. The hypertension-sensitive rats had higher hypothalamic noradrenaline and lower adrenaline than resistant rats.
3. In response to a high salt diet brain-stem noradrenaline increased in sensitive rats and resistant rats exhibited a decrease on the same diet.