How is intravascular volume leading to HTN?

When NaCl intake exceeds capacity of kidney to excrete sodium, vascular volume expands and CO may increase (flow = pressure across vessels/resistance) Initial increase of pressure is related to increased CO, but over time we get increased resistance and CO returns normal. Also salt activates neural/endocrine/vascular mechanisms increasing arterial blood pressure. Mechanism of pressure-natriuresis involves increase in GFR, decrease in absorbing capacity of renal tubules and hormonal factors like ANF, if pt with impaired capacity to remove sodium we get greater increase in BP to get normal natriuresis. This could be due to renal disease/increased production of mineralocorticoids