Ethnic differences in the renal sodium-dopamine relationship: a possible explanation for regional variation in the prevalence of hypertension?

Twenty-four-h urinary sodium and dopamine output by normotensive adults from 5 different ethnic groups have been measured. The groups differed substantially in the correlation between the urinary output to sodium and dopamine. Those with a traditionally salt rich diet (Thais, Caucasians, Zimbabweans) showed a strong positive correlation (p less than 0.001), whereas no such relationship was found in West Africans and Iranians, who come from traditionally salt scarce environments. It is hypothesised that in some races the lack of or uncoupling of the renal sodium-dopamine relationship, possibly as a mechanism to help conserve dietary sodium, predisposes to the development of hypertension when the individuals encounter a salt rich diet.