Salt Intake, Salt Sensitivity and Hypertension in Nigerians: An Overview.

It is widely recognized that a high dietary intake of salt can result in hypertension and various studies have confirmed this link. Epidemiological studies have shown that communities that consume large amounts of salt in their diet have a high incidence of hypertension. Studies in experimental animals show that giving high salt in the diet can result in high blood pressure. Some of the mechanisms responsible for this observation include enhanced constriction response as well as reduced relaxation of resistance vessels. There also appears to be sexual dimorphism in the responses. In humans, our experiments have reported elevated blood pressure in response to oral salt loading and this elevation or Salt Sensitivity may be related to increased salt retention. Some suggestions include genetic defect in the renal tubules in the handling of sodium ions, due to mutation in the Epithelial Sodium Channel (ENaC), which is common in blacks. Our studies with the drug, amiloride that blocks ENaC tend to confirm this, as well as experiments that test sympathetic nervous system mechanisms by the Cold Pressor Test (CPT) which confirm vascular hyperreactivity. Subsequently we hope to conclude genetic studies on ENaC polymorphism and mutations in our subjects. The eventual goal is the development of screening mechanisms to identify individuals that are salt sensitive and so advise on dietary salt restriction in order to reduce the incidence of hypertensio