Glomerular feedback for decreased GFR is by

Whenever blood flow to the kidney diminishes, renin is secreted and angiotensin is formed. The angiotensin causes widespread vasoconstriction and elevation of blood pressure consequent to greatly increased total peripheral resistance. A second effect, the increased secretion of aldosterone, results in retention of salt and water by the kidneys and therefore increased extracellular fluid volume, cardiac output, and aerial pressure. Additionally, the angiotensin acts directly on the kidneys to cause salt and water retention, which causes a long-term increase in aerial blood pressure.Ref: Ganong&;s Review of Medical Physiology, 23rd edition, page no: 669