Total vascular resistance would remain unchanged if the drop in resistance caused by dilation of the afferent arteriole were exactly matched by the increase in resis­tance caused by contraction of the efferent arteriole. If vascular resistance is unchanged, renal blood flow remains unchanged. In contrast, both dilation of the afferent arteriole and contraction of the efferent arteri­ole would increase glomerular hydrostatic pressure and, consequently, glomerular filtration rate (GFR). An increase in GFR with no change in renal blood flow would lead to an increase in filtration fraction.