Heterogeneous localization of connexin40 in the renal vasculature

The renal circulation, which treats 25% of the cardiac output, is organized and regulated in unique patterns. Gap junction channels may contribute to the control of vascular tone by transmitting intracellular signals rapidly between cells of the blood vessel. We investigated the distribution pattern s of the major vascular gap junction proteins in the murine kidney by immun ofluorescence staining of frozen sections, and connexin40 (Cx40) was the mo st prominent connexin detected. The endothelial cells of large vessels with in the kidney consistently showed abundant Cx40 immunoreactivity, but small vessels showed unique distributions of Cx40 along their courses within the kidney. Cx40 immunoreactivity between endothelial cells was abundant in th e interlobular arteries and the proximal portion of the afferent arterioles , but was significantly decreased when arterioles approached the glomerulus . No Cx40 immunoreactivity was detected in the region of the glomerular ist hmus where the afferent and efferent arterioles join the glomeruli, althoug h glomeruli showed very intense patchy staining for Cx40. Intense patchy st aining for Cx40 was also found in the modified smooth muscle cells of the j uxtaglomerular apparatus, but none was detected in smooth muscle cells else where in the vasculature. Taken together, these data suggest that the abund ance of Cx40-containing gap junctions may be important for coordinating fun ction of cells within individual blood vessels, while their absence in juxt aglomerular regions of the arterioles may prevent conduction of signals bet ween the glomerulus and afferent or efferent arterioles. (C) 2000 Academic Press.