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When renal blood flow is reduced (indicating hypotension) or there is a decrease in sodium or chloride ion concentration, the macula densa of the distal tubule releases prostaglandins (mainly PGI2 and PGE2) and nitric oxide, which cause the juxtaglomerular cells lining the afferent arterioles to release renin, activating the renin–angiotensin–aldosterone system, to increase blood pressure ...
The muscle tension in the afferent arteriole is modified based on the difference between the sensed concentration and a target concentration. [5] Vasodilation of the afferent arteriole, which results in increased glomerular filtration pressure and tubular fluid flow, occurs when MD cells detect a chloride concentration that is below a target value.
In the kidney, the macula densa is an area of closely packed specialized cells lining the wall of the distal tubule where it touches the glomerulus.Specifically, the macula densa is found in the terminal portion of the distal straight tubule (thick ascending limb of the loop of Henle), after which the distal convoluted tubule begins.
These cells are similar to epithelium and are located in the tunica media of the afferent arterioles as they enter the glomeruli. [4] The juxtaglomerular cells secrete renin in response to: Stimulation of the beta-1 adrenergic receptor; Decrease in renal perfusion pressure (detected directly by the juxtaglomerular cells)
In the kidneys, angiotensin II constricts glomerular arterioles, having a greater effect on efferent arterioles than afferent. As with most other capillary beds in the body, the constriction of afferent arterioles increases the arteriolar resistance, raising systemic arterial blood pressure and decreasing the blood flow. However, the kidneys ...
Changes in the resting membrane potential of the cell affects the level of intracellular calcium through modulation of voltage-sensitive calcium channels in the plasma membrane. adenosine: cAMP-mediated Adrenergic stimulation results in elevated levels of cAMP and protein kinase A, which results in increasing calcium removal from the cytoplasm.
Adenosine used as a second messenger can be the result of de novo purine biosynthesis via adenosine monophosphate (AMP), though it is possible other pathways exist. [28] When adenosine enters the circulation, it is broken down by adenosine deaminase, which is present in red blood cells and the vessel wall.
The sodium chloride levels in the urinary filtrate are sensed by the macula densa cells at the end of the ascending limb. When sodium levels are moderately increased, the macula densa releases ATP [12] and reduces prostaglandin E2 release [13] to the juxtaglomerular cells nearby. The juxtaglomerular cells in the afferent arteriole constrict ...