Essential hypertension is believed to be a heterogeneous group of disorders, the subtypes of which could be related to sodium sensitivity, obesity, diabetes, calcium intake and metabolism, the renin-angiotensin balance, or membrane cation transport. Essential hypertension aggregates in families. The syndromes leading to hypertension may involve shared genes, shared environmental factors, or both.
In 1980 a series of biochemical and physiological tests were initiated in the 2,548 persons in 98 extended pedigrees in Utah. Most of the subjects were obtained from three major pedigree types: stroke cluster pedigrees; coronary heart disease cluster pedigrees; and pedigrees of Utah Hypertension Detection and Follow-up Program high blood pressure probands. Data were collected on personal history, medical family history and genealogy, anthropometrics, standard and 32-lead electro- cardiograms, multiple blood pressure measurements during sitting, standing, lying, tilting, isometric hand grip exercise, bicycle exercise, venipuncture and mental arithmetic. Cation tests included sodium-lithium countertransport, lithium-potassium co-transport, intracellular sodium, potassium, magnesium, sodium-potassium ATP-ase pump activity and binding sites and plasma levels of sodium, potassium, magnesium, ionized calcium and digoxin-like pump inhibitor. Information was also collected on stress, exercise, plasma renin activity, and urinary kallikrein. Statistical and pedigree analysis were conducted.
The same tests were also performed on 600 new population-based hypertensive subjects on drug therapy and again four months after interruption of drug therapy. Tests were conduced for specific subtypes of high blood pressure among the 600 subjects using individual variables and multivariate combinations of variables. Three hundred nuclear families were screened to test for familiality of subtype indicators and to identify those high blood pressure subtype indicator variables needing detailed pedigree analysis.
One thousand sequentially-sampled persons were studied for major genes, DNA probe linkage, and gene-environment interactions as determinants of specific types of hypertension.