I vasodilatatori endoteliali controbilanciano l’azione dell’endotelina-1

In 10 anaesthetized and mechanically ventilate Large White pigs we analysed the activity of Endothelin-1 (ET-1) and the involvement of prostacyclin (PGI2) and nitric oxide (NO) as modulators of ET-1 activity. Parameters evaluated were: systemic (MAP) and pulmonary arterial pressure (MPAP), heart rate (HR), cardiac output (CO) and systemic (SVR) and pulmonary vascular resistances (PVR). Results showed that ET-1 (100 pmol/kg i.v.) induces a biphasic response both on pulmonary and systemic vascular bed. This was characterised by an early and transient hypotension, followed by an hypertensive activity lasting about 20'. Blocking NO by NG-nitro-L-arginine methyl ester (L-NAME 5 mg/kg i.v.), or PGI2 by indomethacin (3 mg/kg i.v.), the hypotensive activity ET-1-dependent on systemic vascular bed, at difference to pulmonary one, disappears. This data show that ET-1 at systemic level induces the release of NO and PGI2, while at pulmonary level its hypotensive activity is probably due to other vasoactive metabolites.