Long-lasting vasoconstriction

Long-lasting vasoconstriction is produced by the ETs in almost all arteries and veins and several studies have shown that ET-1 causes a reduction in renal blood flow and urinary sodium excretion. ET-1 has been reported to be a potent mitogen in fibroblasts and aortic smooth muscle cells and to cause contraction of rat stomach strips, rat colon and guinea pig ileum. In the central nervous system, ETs have been shown to modulate neurotransmitter release. 

In the vascular system, endothelial ETB receptors mediate a transient vasodilation, whereas ETA receptors cause a long-lasting vasoconstriction. The role of ETb receptors expressed on smooth muscle cells... 

Neuropeptide Y (NPY) Found in many noradrenergic neurons. Present in some secretomotor neurons in the ENS and may inhibit secretion of water and electrolytes by the gut. Causes long-lasting vasoconstriction. It is also a cotransmitter in some parasympathetic postganglionic neurons. 

Lesions of pulmonary endothelial cells Gl tract hemorrhage portal vein thrombosis Long-lasting renal vasoconstriction... 

FIGURE 44 Endothelial cells synthesize and release substances that cause vasoconstriction or vasorelaxation. Endothelin is a potent, slow-acting and long-lasting vasoconstrictor peptide that exerts a wide variety of effects. 

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