In angiotensin II (Ang II)-dependent hypertension, the augmented intrarenal Ang II constricts the renal microvasculature and stimulates Rho kinase (ROCK), which modulates vascular contractile responses. Rho may also stimulate angiotensinogen (AGT) expression in preglomerular vascular smooth muscle cells (VSMCs) but this has not been established. Therefore, the aims of this study were to determine the direct interactions between Rho and Ang II in regulating AGT and other renin-angiotensin system (RAS) components and to elucidate the roles of the ROCK/nuclear factor kappa B (NFB) axis in the Ang II-induced AGT augmentation in primary cultures of preglomerular VSMCs. We first demonstrated that these preglomerular VSMCs express renin, AGT, angiotensin converting enzyme, and Ang II type 1 (AT1) receptors. Furthermore incubation with Ang II (100 pmol/L for 24 hr) increased AGT mRNA (1.42 ± 0.03, ratio to control) and protein (1.68 ± 0.05, ratio to control) expression levels, intracellular Ang II levels and NFB activity. In contrast, the Ang II treatment did not alter AT1a and AT1b mRNA levels in the cells. Treatment with H-1152 (ROCK inhibitor, 10 nmol/L) and ROCK1 siRNA suppressed the Ang II-induced AGT augmentation and the upregulation and translocalization of p65 into nuclei. Functional studies showed that ROCK exerted a greater influence on afferent arterioles responses to Ang II in rats subjected to chronic Ang II infusions. These results indicate that ROCK is involved in NFB activation and the ROCK/NFB axis contributes to Ang II-induced AGT upregulation, leading to intracellular Ang II augmentation.