Figure 20-13 Neurohormonal regulation of renal function. Normally, a balance is present between systems promoting renal vasoconstriction and sodium retention versus systems promoting renal vasodilation and sodium excretion. Surgical stress, ischemia, and sepsis tip the balance in favor of vasoconstriction and sodium retention. On the other hand, hypervolemia (or induction of atrial stretch) tips the balance in favor of vasodilation and sodium excretion.