Ascending brain-stem noradrenergic pathways modulate the renin response to haemorrhage.

Ventral noradrenergic projections (VNAB) from lateral tegmental (A1, A2) and dorsal noradrenergic projections (DNAB) from the coeruleal (A6) as well as A1 cell groups in the brain-stem of the rat were lesioned by intracerebral injection of 6-hydroxydopamine. A marked increase in plasma renin activity and adrenaline concentrations followed haemorrhage (0.5 ml/100 g body weight) in the sham-operated rats. VNAB-lesioned rats showed a similar response to the sham-operated controls, but in DNAB-lesioned animals the rise of plasma renin was markedly attenuated.