Hypertension and Your Kidneys: any Relationship?

The relationship between hypertension and kidney disease is such that it is difficult to determine which of them precedes the other. It is a known fact that hypertension can cause kidney problems, especially the chronic types such as chronic pyelonephritis, nephrosclerosis, etc and it is also known that kidney diseases such as acute or chronic glomerulonephritis can cause hypertension.
When there is a renal (kidney) problem e.g. glomerulonephritis which is primarily caused by streptococcal or other infections, there is an inflammation of the glomeruli of the kidneys. This inflammatory process brings about reduced blood supply to the renal vessels as a result of the swelling that accompanies the inflammation. Reduced blood supply ensures that Renin (an enzyme) is released into the blood stream. The released rennin now leads to the breakdown of Angiotensinogen (plasma protein) into angiotensin I. Angiotensin I is further acted upon by Angiotensin-converting-enzyme (ACE) which is found in the lungs, converting it into angiotensin II. This angiotensin II leads to the secretion of Aldosterone (which stimulates salt and water re-absorption by the kidneys), and constriction of arterioles thereby leading to an elevation in both systolic and diastolic blood pressures.
The elevated blood pressure on the other hand brings about renal ischaemia (reduced blood supply to the kidneys), thereby leading to a further release of renin into the blood stream. The release of rennin leads to a further rise in the blood pressure by ensuring that more angiotensinogen is converted into angiotensin I to continue the cycle. But the use of drugs known as ACE inhibitors can help to disrupt this process or minimize the rate at which angiotensin I is converted to angiotensin II thereby bringing the hypertension under control.
However, high blood pressure reduces blood supply to the kidneys (a condition referred to as renal ischaemia); and if the kidneys remain deprived of blood and oxygen supply for a long period of time physiological changes and complications begin to occur in them and they become susceptible to infections: there could be recurrent renal infections. This is where pyelonephritis and nephrosclerosis come in. With nephosclerosis there is further constriction of the arterioles of the kidneys and as such more release of rennin, and by extension another increase in blood pressure. Recurrent renal infection could lead to chronic pyelonephritis and eventually to kidney failure if not managed on time. Therefore, renal problems should be promptly managed to prevent hypertension, and hypertension should as well be controlled to reduce the possibility of renal disease.