Gap junctional intercellular communication in the juxtaglomerular apparatus

1 Department of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi; and 2 Department of Cellular Physiology, Institute of Nephrology, Niigata University, Niigata, Japan Submitted 16 October 2008 ; accepted in final form 9 December 2008 ABSTRACT The juxtaglomerular apparatus (JGA) is a specialized contact region between the glomerulus and the cortical thick ascending limb that plays an active role in the maintenance of ion homeostasis and control of blood pressure. The JGA accommodates several different cell types, including vascular smooth muscle cells, endothelial cells, mesangial cells, macula densa cells, and renin-secreting juxtaglomerular granular cells. These cells, with the exception of the macular densa cells, are tightly coupled by gap junctions. Gap junction-mediated intercellular communication in the JGA provides a pathway for signal transduction and coordination of multicellular functions. Disruption of cell-to-cell communication in the JGA results in altered preglomerular vascular tone and renin secretion. This review summarizes recent data about the roles of gap junctions in the JGA and illustrates how gap junction-mediated intercellular Ca 2+ signals determine physiological responses in the JGA. gap junction; intercellular calcium signal; renal autoregulation Address for reprint requests and other correspondence: J. Yao, Dept. of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, Univ. of Yamanashi, Chuo, Yamanashi 409-3898, Japan (e-mail: yao{at}yamanashi.ac.jp )