Endothelium Function and Pathology (Brodsky) Flashcards
Most relevant endothelium functions
Blood vessel diameter (blood pressure / supply), Coagulation
What is the most relevant endothelium pathology?
Atherosclerosis
What local factors affect arteriolar constriction locally?
Decreased local temperature, autoregulation
Local local factors affecting arteriolar dilatation
Increased CO2 and decreased O2, Increased K+, adenosine, lactate, etc., Decreased local pH, Increased local temperature.
Hormones affecting constriction of arterioles
Adrenaline (except in skeletal muscle and liver), Noradrenaline, AVP, Angiotensine II, Circulating Na+-K+ ATPase inhibitor, Neuropeptide Y
Hormones affecting dilatation of arterioles
Epinephrine in skeletal muscle and liver, CGRP, Substance P, histamine, ANP, VIP.
What neural factors affect arteriolar constriction?
Increased discharge of sympathetic neurons.
What neural factors affect arteriolar dilation?
Decrease discharge of sympathetic neurons, Activation of sympathetic cholinergic vasodilator nerves to skeletal muscle.
What endothelial products affect arteriolar constriction?
Endothelin-1, Locally released platelet serotonin, Thromboxane A2.
What endothelial products affect arteriolar dilation?
NO, Kinins, Prostacyclin
What is the use of serotonin?
Brain and blood vessels. Vasoconstriction. Related to depression and migraine headaches.
What are signaling molecules?
Signaling molecules derived from different 20-carbon essential fatty acids.
What is the most important 20-carbon essential fatty acid that forms eicosanoids
Arachidonic acid
Functions of Eicosinoids
Functions: Regulation of blood pressure, Coagulation, Inflammation, Fever, Immune system modulation, Control of reproductive processes, Regulation of sleep/wake cycle.
What are the classical eicosanoids synthesized by?
Cyclooxygenase (COX1/2) or Lipoxygenases (LOX)
What are the 2 classes of eicosanoids?
Prostanoids (from COX) and leukotriens (from LOX)
What are the prostanoids?
Prostaglandings (PG), Prostacyclins (PGI2), Thromboxanes (TX)
Formation of Eicosanoids: pathway through LOX or COX
Where are prostacylcins produced?
Endothelial cells
Where is Thromboxane A2 produced?
In platelets
From what are Prostacyclins and Thromboxane A2 produced?
Arachidonic acid via Cyclooxygenase pathway
What is the actino of thromboxane A2?
Promotes platelet aggregation and vasoconstriction
What is the response to prostacyclin?
Inhibition of platelet aggregation and vasodilation. Vascular relaxation, blocks platelet reactivity, stimulates cytokine production.
What is the effect of aspirin on Thromboxane A2 and Prostacyclin
Shifts balance between them towards prostacyclin. Produces irreversible inhibition of COX reducing productino of both but endothelial cells can recover while platelets cannot
How is NO synthesized?
From arginine in a reaction catalyzed by NO synthase (NOS)
What are the 3 isoforms of NOS?
NOS1-nervous system, NOS2-macrophages and other immune cells, NOS3-endothelial cells
What is the effect of NO on blood vessels
Diffuses through endothelium (intima to media) to smooth muscle, activates soluble guanylyl cyclase producing cGMP, mediates relaxation of vascular smooth muscle-vasodilation. Inhibits platelet reactivity.
What inactivates NO?
Hemoglobin
What common pharmaceutical use does NO have?
Viagra and cialis