CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 1, February 2012
AFRICA
31
in the progression of sub-clinical atherosclerosis.
25
From Fig. 2 it is clear that hypertensive men and women
showed increased vascular responses when subjected to acute
mental stress. Malan
et al.
demonstrated that a shift from
central to more vascular blood pressure responses could be
due to uncontrollability of psychosocial stress experienced by
Africans.
11
This may imply that Africans feel overwhelmed with
the present-day problems they face. These findings strengthen
the idea of more peripheral cardiovascular reactions to stress in
hypertensive Africans.
11,26
In support, Nyklí
č
ek
et al.
added that
hypertensives have been found to have a more reactive cardio-
vascular system than normotensives, and that they show a greater
mean DBP reactivity when stressed.
3
Therefore, this study
strengthens these findings and those of Malan
et al.
, indicating
that Africans exhibit peripheral resistance responses at
rest and
when exposed to stressful situations.
11,27
Glucose and salivary cortisol levels in both the normo-
tensive and hypertensive men and women were high-normal
(International Diabetes Federation, 5.6 mmol/l; 0.76–2.94ng/
ml,
28
respectively). HPAA hypo-activity seems to be likely
in humans experiencing chronic stress, but in hypertensive
Africans, their increased resting high-normal cortisol levels
could also be due to receptor down-regulation in the hippocam-
pus.
29,30
The resting high-normal cortisol values in particularly
the men could impair negative feedback to the hippocampus as a
TABLE 1. DESCRIPTIVE STATISTICSANDANALYSIS OF CO-VARIANCES, ADJUSTED FORAGEAND BMI,
BETWEEN NORMOTENSIVEAND HYPERTENSIVEAFRICAN MENANDWOMEN
Men
Women
Normotensive
Hypertensive
Normotensive
Hypertensive
Participants,
n
37
64
65
34
Anthropometrics
Age (years)*
40.9 ± 7.65*
44.5 ± 8.04*
43.7 ± 6.65*
48.6 ± 9.01*
BMI (kg/m
2
)*
26.1 ± 5.12
28.4 ± 6.01
31.1 ± 5.88*
35.9 ± 8.47*
WC (cm)
93.5 (91.7, 95.3)
93.6 (92.3, 95.1)
91.9 (89.9, 93.9)*
96.8 (93.9, 99.6)*
CV parameters
SBP rest (mmHg)
137 (131, 143)*
152 (147, 156)*
131 (128, 134)*
146 (142, 151)*
DBP rest (mmHg)
81.1 (77.7, 84.5)*
88.6 (86.1, 91.2)*
74.6 (72.8, 76.4)*
82.1 (79.5, 84.6)*
CO rest (l/min)
6.79 (6.20, 7.38)
6.67 (6.22, 7.12)
7.08 (6.67; 7.49)
6.90 (6.32; 7.49)
TPR rest (mmHg/ml/s)
0.97 (0.87, 1.07)*
1.13 (1.05, 1.20)*
0.89 (0.79, 0.99)*
1.09 (0.95, 1.24)*
Cw rest (ml/mmHg)
2.03 (1.93, 2.14)*
1.79 (1.70, 1.87)*
1.94 (1.87, 2.00)*
1.70 (1.61, 1.81)*
Other parameters
IMT
f
mean (mm)
0.72 (0.68, 0.77)
0.69 (0.66, 0.73)
0.67 (0.64, 0.71)
0.68 (0.64, 0.72)
Cortisol rest (ng/ml)
2.27 (1.58, 2.96)
2.39 (1.87, 2.91)
1.81 (1.38, 2.22)
1.86 (1.26, 2.46)
Glucose (mmol/l )
5.79 (5.21, 6.39)
5.50 (5.07, 5.93)
5.61 (5.00, 6.23)
5.77 (4.89, 6.64)
Smoking,
n
(%)
10 (27.0)
21 (32.8)
0 (0.00)*
3 (8.82)*
Alcohol usage,
n
(%)
13 (35.1)
28 (43.8)
6 (9.23)
5 (14.7)
Hytension medication (%)
5 (13.5)
10 (15.6)
10 (15.4)*
11 (32.4)*
Diabetes medication (%)
2 (5.41)
1 (1.56)
2 (3.08)
1 (2.94)
HIV,
n
(%)
2 (5.41)*
11 (17.2)*
3 (4.62)
2 (5.88)
PAI low,
n
(%)
30 (81.1)
48 (75.0)
45 (69.2)
24 (70.6)
Coping strategies
High problem solving
31.2 (30.2, 32.3)
31.1 (30.3, 32.1)
31.2 (30.3, 32.1)
31.1 (29.7, 32.2)
Low problem solving
23.1 (21.5, 24.8)**
25.0 (23.6, 26.5)**
23.9 (21.7, 26.1)
22.2 (19.6, 24.8)
High avoidance
24.8 (23.1, 26.5)
23.4 (21.9, 24.9)
23.2 (21.5, 24.9)
24.3 (22.3, 26.3)
Low avoidance
16.5 (15.2, 17.8)
17.3 (16.3, 18.4)
17.8 (16.5, 19.1)
18.4 (16.8, 20.1)
High social support
28.9 (28.0, 29.8)
29.5 (28.7, 30.2)
29.0 (28.1, 30.1)
28.1 (26.5, 29.5)
Low social support
20.4 (18.3, 22.6)
21.5 (20.0, 22.9)
20.6 (18.9, 22.3)
20.3 (18.4, 22.3)
Values are given with 95% confidence interval. *Values are given according to mean
±
standard deviation.
n
, number per group; BMI, body mass
index; WC, waist circumference; SBP, systolic blood pressure; DBP, diastolic blood pressure; CO, cardiac output; TPR, total peripheral resistance;
Cw, Windkessel compliance; IMT
f
, intima media thickness of far wall; HIV, human immune deficiency virus; PAI, physical activity index.
Means with the same superscript letter differ significantly, when
p
≤
0.05, when in italic,
p
≤
0.09.
TABLE 2. FORWARD STEPWISE REGRESSION
ANALYSES PREDICTINGTHE RELATIONSHIP
BETWEEN SUB-CLINICALATHEROSCLEROSIS (CIMT)
AND CARDIOVASCULAR RESPONSES IN
HYPERTENSIVEAFRICAN MEN
Carotid intima–media thickness
Model 1:
hypertensive men, time 1
(
n
=
32)
Model 2:
all hypertensive men
(
n
=
60)
Adjusted
R
2
0.61
0.32
b
(
±
95% CI)
b
(
±
95% CI)
Age
0.62 (0.35, 0.89)*
0.55 (0.33, 0.77)*
DBP%, CPT
1.04 (0.16, 1.92)
†
b
denotes standardised regression coefficient and degrees of freedom
to enter model, 1.5. Analyses adjusted for resting blood pressure
values, where: *
p
≤
0.01,
†
p
≤
0.05.
