Neuropeptide Y and hypertension.

Neuropeptide Y is a cotransmitter in the sympathetic nervous system with potent contractile effects on blood vessels. The plasma levels of neuropeptide Y-like immunoreactivity in patients with severe hypertension (> 120 mmHg) were increased compared with the levels in control subjects and were still elevated after long-term pharmacologic treatment of normotension. Neuropeptide Y stimulated DNA synthesis, total cell number, and total protein production in human vascular smooth muscle cells through a Y1-receptor. A Gi/G(o)-coupled second messenger mechanism seems to be involved, because pretreatment with pertussis toxin abolished the mitogenic effect. Neuropeptide Y potentiated the mitogenic effect of noradrenaline, and together with adenosine 5'-triphosphate, the sympathetic cotransmitters reached a mitogenic effect of approximately 20% of fetal calf serum. We have shown that neuropeptide Y, noradrenaline, and adenosine 5'-triphosphate, apart from their effects on vascular tone, are stimulators of vascular smooth muscle cell growth. The receptors that mediate the mitogenic effect have been examined. The circulating plasma levels are increased in patients with severe hypertension. These findings indicate that the sympathetic cotransmitter neuropeptide Y may be of importance in sympathetic vascular regulation and involved in pathophysiologic conditions.