How is the glomerular filtration rate regulated?
It is perfectly normal for your blood pressure to fluctuate throughout the day; however, perhaps surprisingly, this has no effect on your glomerular filtration rate. This is because under normal circumstances, your body can precisely control it:
Intrinsic mechanisms:
Renal autoregulation - the kidney itself can adjust the dilation or constriction of the afferent arterioles, which counteracts changes in blood pressure. This intrinsic mechanism works over a large range of blood pressure, but can malfunction if you have kidney disease.
Graph of renal autoregulation occurring between 80 and 160mm Hg mean arterial pressures
Extrinsic mechanisms:
Neural (nervous system) control and hormonal control - these extrinsic mechanisms can override renal autoregulation and decrease the glomerular filtration rate when necessary. For example if you have a large drop in blood pressure, which can happen if you lose a lot of blood, your nervous system will stimulate contraction of the afferent arteriole, reducing urine production. If further measures are needed your nervous system can also activate the renin-angiotensin-aldosterone system, a hormone system that regulates blood pressure and fluid balance.
Hormonal control - atrial natriuretic peptide is a hormone that can increase the glomerular filtration rate. This hormone is produced in your heart and is secreted when your plasma volume increases, which increases urine production.