Final answer:
Constriction of the afferent arteriole reduces Glomerular Filtration Rate by decreasing blood flow and pressure in the glomerular capillaries, leading to reduced filtration into the renal tubules.
Step-by-step explanation:
Yes, constriction of the afferent arteriole reduces the Glomerular Filtration Rate (GFR). The afferent arteriole is the blood vessel supplying the glomerulus in the kidney, where filtration of blood takes place. Constriction of the afferent arteriole would decrease the blood flow into the glomerulus, thereby reducing the pressure within the glomerular capillaries. This decrease in pressure leads to a lower GFR as less fluid is pushed across the filtration membrane into the renal tubules.
Several mechanisms regulate blood flow to the glomerulus and GFR, including the myogenic mechanism, tubuloglomerular feedback, sympathetic nervous system control, and various hormonal controls like renin-angiotensin-aldosterone system. Constriction can occur in response to factors such as increased sympathetic nervous activity, signaling from the macula densa cells due to increased or decreased Na+ concentration in the filtrate, or hormonal signals such as angiotensin II. These are all part of a well-coordinated system that maintains homeostasis of blood pressure and fluid balance.