A smooth muscle cell found in the wall of the afferent arteriole. This cell contracts and relaxes in response to changes in blood pressure, a process known as a myogenic response, to alter artery diameter and regulate blood flow into the glomeruli. [ http://www.ncbi.nlm.nih.gov/pubmed/24066938 http://www.ncbi.nlm.nih.gov/pubmed/25834230 http://www.ncbi.nlm.nih.gov/pubmed/16990493 http://www.ncbi.nlm.nih.gov/pubmed/22733355 ]