| Juxtaglomerular cell |
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| Microscopic image of juxtaglomerular cells |
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| Drawing of renal corpuscle (juxtaglomerular cells are labeled as number 6) |
The juxtaglomerular cells (JG cells, or granular cells) are cells in the kidney that synthesize, store, and secrete the enzyme renin. They are specialized smooth muscle cells in the wall of the afferent arteriole (and sometimes the efferent arteriole) that delivers blood to the glomerulus. In synthesizing renin, they play a critical role in the renin-angiotensin system and thus in renal autoregulation, the self-governance of the kidney. They secrete renin in response to the detection of low sodium concentration by the macula densa cells located on the distal convoluted tubule which has direct contact with its own afferent arterioles.
In appropriately stained slides, juxtaglomerular cells are distinguished by their granulated cytoplasm.
Similar to cardiac tissue, juxtaglomerular cells harbor β1 adrenergic receptors. When stimulated by epinephrine or norepinephrine, these receptors induce the secretion of renin. These cells also respond directly to a decrease in systemic blood pressure which is manifested as a lower renal perfusion pressure.
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