Culture of vascular smooth muscle cells from small arteries of the rat kidney

Background. In contrast to arterioles, small arteries appear to be the pref erential site of renal vascular smooth muscle cell (VSMC) proliferation und er pathophysiological conditions. To date, techniques have been described t o isolate renal arterioles and to culture VSMCs. The aim of the present stu dy was to develop a method of culturing VSMCs from isolated small arteries of the rat kidney and to characterize their growth as compared with that of aortic VSMCs. Methods. Renal vascular trees were isolated from kidneys of male Wistar rat s by a sieving technique. VSMCs were grown from explants of collagenase-tre ated renal vascular trees and thoracic aorta. Growth curves and proliferati on of renal and aortic VSMCs in response to fetal bovine serum (FBS) were c ompared by determination of cell number and DNA synthesis, measured as inco rporation of 5-bromo-2'-deoxyuridine. Results. Renal vascular trees consisted mainly of small arteries with a dia meter of 80 to 400 mu m (interlobar and arcuate arteries). As compared with total kidney or renal cortex, alkaline phosphatase activity was decreased by 81%, and vasopressin (10 mu mol/L) was unable to stimulate adenylyl cycl ase in renal vascular trees, indicating little tubular contamination. A hom ogenous population of spindle-shaped cells was cultured from renal vascular trees, which grew in a hill-and-valley pattern and stained positively for smooth muscle alpha-actin, according to the characteristics of VSMC phenoty pe. Renal VSMCs proliferated more slowly than aortic VSMCs and reached the plateau of growth at about half of the cell density of aortic VSMCs. Furthe rmore, proliferation of renal VSMCs depended more heavily on FBS concentrat ion, since about threefold higher concentrations of FBS were needed for ren al VSMCs to multiply at the same rate and to similarly stimulate DNA synthe sis as compared with aortic VSMCs. Conclusions. We present a method to culture renal VSMCs from small arteries of the rat kidney, which possess distinct growth characteristics as compar ed with aortic VSMCs.