Constriction of the afferent aeriole to the kidney glomerulus results in:

The kidney is innervated primarily by the sympathetic nervous system, and as such, regulates the contraction of the smooth muscle surrounding the afferent and efferent aerioles of the glomerulus. Sympathetic stimulation to the efferent glomerular aerioles causes their constriction and increases the filtration rate, leading to an increase in urinary output. Similarly, with the loss of sympathetic innervation, such as due to sympathectomy of the kidney, relaxation of tone of the afferent aeriole occurs and the filtration rate increases, which results in an increased urine output. Decreased urine output may result from the constriction of the afferent aerioles, leading to a decrease in glomerular filtration rate. Also Know: Factors affecting the GFR: Changes in renal blood flow Changes in glomerular capillary hydrostatic pressure Changes in systemic blood pressure Afferent or efferent aeriolar constriction Changes in hydrostatic pressure in Bowman's capsule Ureteral obstruction Edema of kidney inside tight renal capsule Changes in concentration of plasma proteins: dehydration, hypoproteinemia, etc (minor factors) Changes in Kf Changes in glomerular capillary permeability Changes in effective filtration surface area Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 37. Renal Function & Micturition. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e.