[Vasoactive endothelial factors].
Endothelium-derived vasoactive factors are produced by the endothelium activated by effective stimulus, and with paracrine regulatory activity of the tone/proliferation of the vascular smooth muscle and platelet function. They are divided in two groups: endothelium-derived relaxing and contracting factors. Among the endothelium-derived relaxing factors, PG I2, EDRF (NO or other nitrous compound) and EDHF (still unidentified) have been considered Synthetized by the endothelium after stimulation by plasmatic, platelet-derived and endothelium-derived substances and mechanisms, towards the vascular smooth muscle (myorelaxing/cytostatic) and the platelets (antiaggregation). The endothelium-derived contracting factors include the EDCF1 (endothelins, 21 amino acids peptides), EDCF2 (O2-) and TxA2. Its production, induced by stimulus similar to those for relaxing factors, promotes constriction/mitogenesis of the vascular smooth muscle and platelet aggregation. Probably, endothelin-1 has indirect actions over hormonal mechanisms of cardiovascular and renal regulation. The vascular system establishes a tight regulation over the production of these endothelium-derived vasoactive factors. Its loss (usually due to alteration of endothelial responsiveness to stimulation) allows local or generalized modifications of the vascular tone. These can depend on hypertension, atherosclerosis, ischemia-reperfusion lesion, diabetes, inflammation and situations of farmacotoxicity (all developing vasoconstriction/vasospasm) or by septicemia (leading to vasodilation). This disregulation is also involved in the pathogenesis of hypertension, atherosclerosis and ischemia-reperfusion. The vascular tone regulation by endothelium also leads to systemic consequences. Essentially by decreasing cardiac, cerebral and renal blood flow it implies morphologic and functional modifications of these organs.
Feliciano
A
A
Cadeira de Fisiopatologia Geral, Faculdade de Medicina, Lisboa.
do Rosário
H S
HS
Goulão
I
I
Borges
M G
MG
Silva
M
M
Rego
P
P
Silvério
S
S
Pedro
V
V
D000818:Animals; D016232:Endothelins / Q000494:pharmacology / Q000502:physiology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D013329:Structure-Activity Relationship; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D016232:Endothelins
Factores endoteliais vasoactivos.