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Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation , the widening of blood vessels.
Kidney ischemia [1] is a disease with a high morbidity and mortality rate. [2] Blood vessels shrink and undergo apoptosis which results in poor blood flow in the kidneys. More complications happen when failure of the kidney functions result in toxicity in various parts of the body which may cause septic shock, hypovolemia, and a need for surgery. [3]
The signs and symptoms of ischemia vary, as they can occur anywhere in the body and depend on the degree to which blood flow is interrupted. [4] For example, clinical manifestations of acute limb ischemia (which can be summarized as the "six P's") include pain, pallor, pulseless, paresthesia, paralysis, and poikilothermia.
Vasodilation is the opposite of vasoconstriction, which is the narrowing of blood vessels. When blood vessels dilate , the flow of blood is increased due to a decrease in vascular resistance and increase in cardiac output [ further explanation needed ] .
When the blood vessels suddenly relax, it results in vasodilation. In vasodilatory shock, the blood vessels are too relaxed leading to extreme vasodilation and blood pressure drops and blood flow becomes very low. Without enough blood pressure, blood and oxygen will not be pushed to reach the body's organs.
Affected arteries develop endothelial dysfunction and impairment of normal vasodilation, which alter kidney autoregulation. When the kidneys' autoregulatory system is disrupted, the intraglomerular pressure starts to vary directly with the systemic arterial pressure, thus offering no protection to the kidney during blood pressure fluctuations.
Vasospasm refers to a condition in which an arterial spasm leads to vasoconstriction. This can lead to tissue ischemia (insufficient blood flow) and tissue death ( necrosis ). Along with physical resistance, vasospasm is a main cause of ischemia.
Early symptoms of hypovolemia include headache, fatigue, weakness, thirst, and dizziness. The more severe signs and symptoms are often associated with hypovolemic shock. These include oliguria , cyanosis , abdominal and chest pain, hypotension , tachycardia , cold hands and feet, and progressively altering mental status.