Haemodynamic effects of long-term endothelin infusion in conscious sheep

1. Synthetic human endothelin-1 was infused intravenously at 15 micrograms/h for 24 h to examine its cardiovascular actions in five conscious sheep. 2. Endothelin produced a maximum increase in mean arterial pressure (MAP) of +8 mmHg at 8 h, with an increase in calculated total peripheral resistance (CTPR) of +2.6 mmHg/L per min, whilst cardiac output (CO) was unchanged. At 24 h MAP was not significantly elevated, however CTPR had increased by +2.8 mmHg/L per min and CO had decreased by 0.9 L/min. 3. This study shows that long-term administration of endothelin produces sustained arterial vasoconstriction in sheep.