Gender specific sympathetic and hemorrheological responses to mental stress in healthy young subjects.
OBJECTIVE
Activation of the sympathetic nervous system may increase hematocrit (Hct), whole blood viscosity (WBV), and possibly cardiovascular risk. The aim was to study gender specific differences of mental stress on sympathetic reactivity and blood rheology.


METHODS
Responses in blood pressure, heart rate (HR), Hct, WBV (Bohlin rotational viscosimeter), and plasma catecholamines to a mental arithmetic stress test (MST) were measured in male (n = 10, 23 +/- 3 years, BMI 23 +/- 2 kg/m2) and female (n = 10, 21 +/- 4 years, BMI 24 +/- 2 kg/m2) students.


RESULTS
Systolic blood pressure (SBP), diastolic blood pressure (DBP), and HR increased during MST in men and women, and declined to baseline levels after 15 min of recovery. In men, plasma adrenaline increased by 217% during MST (p < 0.01, ANOVA). and plasma noradrenaline increased by 68% (p < 0.05). Hct and WBV at low shear rates (0.5 and 1.1 l/s) increased as well (p < 0.001, p < 0.05, and p < 0.05, respectively). In women, the increase in plasma adrenaline averaged 118% during MST (p < 0.05) while plasma noradrenaline (-3%, p = 0.38), Hct, and WBV at all shear rates remained unchanged. Men and women differed in A adrenaline (p < 0.05), A noradrenaline (p = 0.01), delta Hct (p < 0.05), and delta WBV (p < 0.05). A Hct tended to correlate with delta SBP (r= 0.60, p = 0.07), A DBP (r = 0.57. p = 0.09). and delta HR (r = 0.50, p = 0.14), and correlated significantly with A noradrenaline (r = 0.66, p < 0.05) in men only. Multiple regression analysis showed that gender independently explained 22% of the change in Hct during mental stress.


CONCLUSIONS
Data suggest gender specific differences in sympathetic and hemorrheological responses to mental stress in healthy young subjects. In men, sympathetic responses were related to hemorrheological responses, but not in women. It may be speculated whether such differences in stress responses may contribute to lower cardiovascular risk in premenopausal women than in men.
Ross
A E
AE
Department of Nephrology, Ullevaal University Hospital, Oslo, Norway.
Flaa
A
A
Høieggen
A
A
Reims
H
H
Eide
I K
IK
Kjeldsen
S E
SE
D000328:Adult; D004837:Epinephrine / Q000097:blood; D005260:Female; D006400:Hematocrit; D018056:Hemorheology; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D009638:Norepinephrine / Q000097:blood; D012044:Regression Analysis; D017678:Sex Distribution; D012737:Sex Factors; D013315:Stress, Psychological / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000503:physiopathology*
D009638:Norepinephrine; D004837:Epinephrine