Treadmill exercise-induced stress causes a rise of blood histamine in normotensive but not in primary hypertensive humans

We have previously shown an interaction between noradrenergic and histamine -containing neurons in the rat vas deferens. As a generalized phenomenon, t his interaction is involved in a novel peripheral reflex that, in an inhibi tory way, modulates sympathetic activity and arterial pressure. Consistent with this, an activation of postganglionic sympathetic neurons causes a ris e in rat blood histamine. In the present study, we showed that enhanced sym pathetic activity due to treadmill exercise in normotensive humans, is acco mpanied by a rise in blood histamine, suggesting the presence of a similar neuronal interaction in humans. In contrast, the rise in blood histamine do es not occur in primary hypertensive humans during the same degree of physi cal exercise, suggesting that this interaction is faulty in such hypertensi ves and could be involved in the pathophysiology of the disease. (C) 1999 E lsevier Science B.V. All rights reserved.