can Kidney Disease Cause High Blood Pressure

As we know, many patients with kidney disease will always complain of dizziness, headache and any other symptoms. The patients have these symptoms may be due to their high blood pressure. Then why will kidney diseases will cause high blood pressure?

First we need to make one definition clear-what is Renin? Renin, also known as angiotensinogenase-a kind of acidic proteinase, is an enzyme that participates in the body′s renin-angiotensin system , which will be involved in later. It is secreted by the kidney, or by specialized cells called granular cells of the juxtaglomerular apparatus, to be exact. The renin enzyme circulates in the blood stream and cleaves angiotensinogen secreted from the liver to yield peptide angiotensin I. Under normal condition, little renin is secreted and so is the angiotensin in the blood, which does not affect the blood pressure obviously. Angiotensin, as its name implies, can constrict blood vessels potently, which, however, would not participate in regulation of blood pressure directly under normal conditions. When blood volume in circulation decreases because of the body’ loss of blood, or when blood flow in the kidney is reduced due to kidney disease, Angiotensin will become more in the blood significantly, which has certain effects in maintaining circulating blood volume and arterial blood pressure. As to patients with kidney disease, inflammatory reaction, compression on surrounding tissues, obstruction or other causes inside the kidney will cause insufficient supply of oxygen and blood, which will decrease blood flow of kidney, thus stimulating secretion of rennin by granular cells, as we had mentioned before. Then the renin cleaves angiotensinogen secreted from the liver into the peptide angiotensin I after entering into blood circulation, which we also said before. Angiotensin I is further converted into angiotensin II by ACE, the angiotensin-converting enzyme primarily within the capillaries of the lungs. Then, part of the angiotensin II, under the effect of angiotoninase A in plasma and tissue fluid, is cleaved to angiotensin III.

Angiotensin I can stimulate secretion of Epinephrine by Adrenal Medella, which, can increase heart rate and constricts blood vessels. However, Angiotensin I, itself can not constrict blood vessels directly and significantly. Compared with Angiotensin I, Angiotensin II is the most vasoactive peptide and is a potent constrictor of all blood vessels, which can cause the blood pressure to rise.