1. Sinoaortic deafferentation in the rat leads to increased blood pressure and heart rate.
2. Early increases in tyrosine hydroxylase activity both in brain stem and hypothalamus suggest that increased noradrenaline synthesis may contribute to the development of neurogenic hypertension.
3. After 4 weeks, phenylethanolamine-N-methyltransferase activity was reduced in the hypothalamus.
4. Noradrenaline- and adrenaline, but not dopamine-containing neurones may participate in regulation of sympathetic efferent activity.