Plasma endothelin levels: a meaningless number?
Endothelin (ET)-1 is a potent vasoactive peptide which is mostly secreted toward the vessel wall and the circulatory levels of which are quite low; for these reasons changes in plasma ET-1 may be difficult to detect even after the application of strong stimuli, which, in theory, should profoundly alter its production. We have examined the effects of a number of such stimuli and found that in humans the only one which consistently increased plasma ET-1 was the exposure to hypobaric hypoxia; moreover under these circumstances the increments in plasma ET-1 were correlated with the changes in pulmonary systolic pressure, suggesting a role of circulating ET-1 in the adaptation of pulmonary vessels to high altitude. In contrast no consistent changes of ET-1 were observed in response to sympathetic activation induced either by exposure to cold, standing, reduction in blood pressure and blood withdrawal. In response to angioplasty of renal artery stenosis a concomitant reduction in plasma ET-1 and angiotensin II (AngII) was observed in patients who, prior to angioplasty, had a high degree of activation of the renin system, supporting the possibility that in these specific conditions AngII may actually stimulate ET-1 production in vivo.
Morganti
A
A
Istituto Clinica Medica e Terapia Medica and Centro di Fisiologia Clinica e Ipertensione, Università and Ospedale Maggiore, IRCCS, Milan, Italy.
Marana
I
I
Airoldi
F
F
Alberti
C
C
Nador
B
B
Palatresi
S
S
D000222:Adaptation, Physiological; D017130:Angioplasty; D000804:Angiotensin II / Q000097:blood / Q000187:drug effects; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D001794:Blood Pressure / Q000502:physiology; D003080:Cold Temperature; D019332:Endothelin-1 / Q000097:blood* / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D000860:Hypoxia / Q000097:blood; D007668:Kidney / Q000378:metabolism; D012078:Renal Artery Obstruction / Q000097:blood / Q000601:surgery; D012084:Renin-Angiotensin System / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology
D000806:Angiotensin-Converting Enzyme Inhibitors; D019332:Endothelin-1; D000804:Angiotensin II