Net efflux rate of norepinephrine from platelets in normotensive individuals belonging to families with a heavy accumulation of essential hypertension.

Platelets have been used as a model of sympathetic neurons to study the storage of norepinephrine in normotensive individuals who all had a first degree relative with essential hypertension and had hypertension in the family for at least two generations. The initial rate of efflux of norepinephrine, k, was determined in 44 young relatives (mean age 29.2 years), in 18 middle-aged relatives (mean age 46.7 years) and in 31 young controls with no known family history of essential hypertension (mean age 29.8 years). From the material of relatives all those with definite hypertension had been a priori excluded. k was significantly higher in the young relatives (22.7 +/- 7.9) than in the middle-aged relatives (17.7 +/- 6.4) (p less than 0.05). 27.3% of the relatives had higher k-values than any of the controls. A significant correlation was found between k-value and diastolic blood pressure in controls but not in young relatives.