Endothelin-1 stimulates NO release in the brain and causes a fall in blood pressure

Intracerebroventricular (ICV) infusion of endothelin-1 (ET1) causes NO release in nucleus tractus solitarius (NTS) which results in a fall in blood pressure. This action of NO probably results from the increase in intracellular sodium concentration ([Na(+)](i)) caused by NO. NO concentration increased to 400 +/- 25 nmol/L after injection of 10(-7) mol/L of ET1. In the presence of the endothelin-B receptor (ETB) selective antagonist, A-192621, the NO concentration decreased by 75% causing a slight increase in blood pressure. In our current study, direct observations confirmed that ET1-stimulated changes of NO production in NTS can influence the arterial blood pressure.