Abstract-A large body of evidence has accrued indicating that voltage-gated Ca 2ϩ channel subtypes, including L-, T-, N-, and P/Q-type, are present within renal vascular and tubular tissues, and the blockade of these Ca 2ϩ channels produces diverse actions on renal microcirculation. Because nifedipine acts exclusively on L-type Ca 2ϩ channels, the observation that nifedipine predominantly dilates afferent arterioles implicates intrarenal heterogeneity in the distribution of L-type Ca 2ϩ channels and suggests that it potentially causes glomerular hypertension. In contrast, recently developed Ca 2ϩ

Rhabdomyolysis is a serious syndrome caused by skeletal muscle injury and the subsequent release of breakdown products from damaged muscle cells into systemic circulation. The muscle damage most often results from strenuous exercise, muscle hypoxia, medications, or drug abuse and can lead to life-threatening complications, such as acute kidney injury (AKI). Rhabdomyolysis and the AKI complication can also occur during crush syndrome, an emergency condition that commonly occurs in victims of natural disasters, such as earthquakes, and man-made disasters, such as wars and terrorism. Myoglobin released from damaged muscle is believed to trigger renal dysfunction in this form of AKI. Recently, macrophages were implicated in the disease pathogenesis of rhabdomyolysis-induced AKI, but the precise molecular mechanism remains unclear. In the present study, we show that macrophages released extracellular traps (ETs) comprising DNA fibers and granule proteins in a mouse model of rhabdomyolysis. Heme-activated platelets released from necrotic muscle cells during rhabdomyolysis enhanced the production of macrophage extracellular traps (METs) through increasing intracellular reactive oxygen species generation and histone citrullination. Here we report, for the first time to our knowledge, this unanticipated role for METs and platelets as a sensor of myoglobin-derived heme in rhabdomyolysis-induced AKI. This previously unknown mechanism might be targeted for treatment of the disease. Finally, we found a new therapeutic tool for prevention of AKI after rhabdomyolysis, which might rescue some sufferers of this pathology.

Objective-Induced pluripotent stem (iPS) cells are a novel stem cell population derived from human adult somatic cells through reprogramming using a defined set of transcription factors. Our aim was to determine the features of the directed differentiation of human iPS cells into vascular endothelial cells (ECs) and mural cells (MCs), and to compare that process with human embryonic stem (hES) cells. Methods and Results-We previously established a system for differentiating hES cells into vascular cells. We applied this system to human iPS cells and examined their directed differentiation. After differentiation, TRA1-60 Ϫ Flk1 ϩ cells emerged and divided into VE-cadherin-positive and -negative populations. The former were also positive for CD34, CD31, and eNOS and were consistent with ECs. The latter differentiated into MCs, which expressed smooth muscle ␣-actin and calponin after further differentiation. The efficiency of the differentiation was comparable to that of human ES cells. Conclusions-We succeeded in inducing and isolating human vascular cells from iPS cells and indicate that the properties of human iPS cell differentiation into vascular cells are nearly identical to those of hES cells. This work will contribute to our understanding of human vascular differentiation/development and to the development of vascular regenerative medicine.

Rho-kinase pathway is involved in the pathogenesis of renal injury. Furthermore, the inhibition of Rho-kinase may constitute a therapeutic strategy for the treatment of renal injury in part through the p27kip1 up-regulation and the subsequent inhibition of cell proliferation and macrophage recruitment.