The adreno-sympathetic system, the genetic predisposition to hypertension, and stress

The blood pressure, heart rate, and plasma catecholamine (CA) response to standing and mental stresses were studied in 14 normotensive subjects with normotensive parents (PNT group), 14 normotensive subjects with hypertensive parent(s) (PHT group), and eight borderline hypertensive patients (BHT group). Mean basal plasma norepinephrine (NE) concentration in BHT group (302 +/- 94 pg/ml) and PHT group (289 +/- 167 pg/ml) were significantly higher than in PNT group (205 +/- 76 pg/ml). Significant differences in the mean basal plasma epinephrine (E) were found only between the PNT and BHT groups (22 +/- 12 vs 43 +/- 18 pg/ml, p less than 0.01). Both plasma NE and E increased significantly on standing in all groups. With mental stress, plasma E increased significantly, though plasma NE did not change significantly in all three groups. The mean changes in blood pressure, heart rate, and plasma CA in response to standing and mental stresses were not different in the three groups. However, a higher incidence (50%) of high blood pressure responders (greater than or equal to 20 mmHg in systolic blood pressure) to mental stress was found in the PHT group compared with PNT (14%) and BHT (12%). The high responders in the PHT group had significantly higher mean plasma E concentrations throughout the experiment. Also, their increases in plasma NE and E in response to mental stress were higher than those of the low responders. The results indicate that genetic predisposition to hypertension plays a significant role in determining plasma catecholamine levels and the responsiveness to stress, especially to mental stress.