CARDIOVASCULAR JOURNAL OF AFRICA • Vol 22, No 1, January/February 2011
22
AFRICA
Discussion
Smoking is associated with vascular dysfunction.
1,20,21
Since stud-
ies regarding this topic are limited in South Africa, the objective
was to investigate ethnic differences with regard to the associa-
tion between smoking and cardiometabolic markers. The cardio-
vascular markers related to smoking were generally higher in
Africans (BP, PWV, hs-CRP and cotinine) – a finding supported
by the literature.
9,22
Immense differences in SES between the two groups could
be the contributing factor in this regard. Cheaper mentholated
tobacco brands used by Africans had more nicotine, whereas the
non-mentholated, lighter brands smoked by the Caucasians had
less effect on vascular function.
5
Our results further revealed that
the African smokers were older than the non-smokers, weighed
less, and had lower BMI and WC values. Nicotine accelerates
lipid breakdown
1
and this may lead to weight loss in smok-
ers. Some smokers use tobacco smoke for this purpose,
23,24
and
urbanised South African women are no exception.
25
The LDL-C
and TG levels were higher in Caucasians compared to Africans,
a feature supported by the literature.
26,27
The differences between smokers and non-smokers regard-
ing cardiovascular risk factors were also investigated in both
ethnicities. Significant differences were observed and were in
most cases consistent with findings in the literature.
21,28
Regular
cigarette smoking increases HR and CO acutely throughout the
day,
1
a finding evident especially in the Caucasian smokers. The
increases in HR and CO are mediated by the beta-adrenergic
effects of nicotine.
1
Although nicotine does constrict some
peripheral vascular beds,
4
it is likely that with increased HR
and CO, nicotine appears to dilate other vascular beds through
stimulation of epinephrine release,
1,4
thereby decreasing TPR, as
was found in our study groups.
A finding of this study that was not consistent with the litera-
ture was higher HDL-C levels in African smokers, and this result
is in direct contrast to the significantly lower HDL-C values in
Caucasian smokers. Furthermore, HDL-C values correlated posi-
tively with smoking in Africans, and negatively in Caucasians.
The literature is sparse regarding this finding, although increased
HDL-C levels in smoking Africans with cardiovascular disease
have been mentioned.
28,29
The high HDL-C levels possibly serve
as a defense mechanism in Africans against the oxidative stress
TABLE 4. CORRELATIONS BETWEEN SMOKINGAND MEASURES OF CARDIOVASCULAR
FUNCTIONAND LIPIDS INAFRICAN PARTICIPANTS
Men (
n
=
127)
Women (
n
=
131)
Whole group (
n
=
258)
Smoking duration
Cotinine
Smoking duration
Cotinine
Smoking duration
Cotinine
Variable
r
-value
p
-value
r
-value
p
-value
r
-value
p
-value
r
-value
p
-value
r
-value
p
-value
r
-value
p
-value
SBP (mmHg)
0.22 0.012 –0.05 0.593 0.17 0.043 0.02 0.795 0.23
≤
0.001 0.03 0.680
DBP (mmHg)
0.21 0.019 –0.04 0.678 0.18 0.039 0.03 0.750 0.17 0.006 –0.08 0.901
HR (beats/min)
0.34
≤
0.001 0.07 0.428 0.74 0.403 –0.05 0.586 0.18 0.004 –0.02 0.727
CO (l/min)
–0.13 0.141 –0.12 0.183 –0.28
≤
0.001 –0.18 0.046 –0.20
≤
0.001 –0.16 0.011
TPR (mmHg.s/ml)
0.15 0.104 0.13 0.153 0.33
≤
0.001 0.15 0.096 0.21
≤
0.001 0.01 0.024
Cwk (ml/mmHg)
–0.54
≤
0.001 –0.19 0.035 –0.40
≤
0.001 –0.23 0.008 –0.40
≤
0.001 –0.17 0.006
C-R PWV (m/s)
0.36
≤
0.001 0.15 0.102 0.22 0.012 0.30
≤
0.001 0.36
≤
0.001 0.27
≤
0.001
C-P PWV (m/s)
0.46
≤
0.001 0.16 0.077 0.24 0.005 0.26 0.002 0.41
≤
0.001 0.25
≤
0.001
HDL-C (mmol/l)
0.25 0.005 0.19 0.039 0.21 0.019 0.08 0.352 0.28
≤
0.001 0.18 0.005
LDL-C (mmol/l)
0.08 0.400 0.04 0.641 0.12 0.162 0.12 0.186 0.35 0.578 0.04 0.502
TG (mmmol/l)
0.04 0.684 –0.00 0.995 0.21 0.016 0.22 0.011 0.74 0.239 0.11 0.096
hs-CRP (mg/l)
0.24 0.006 0.09 0.338 0.05 0.556 0.00 0.957 0.95 0.132 0.01 0.932
Cotinine (ng/ml)
0.44
≤
0.001 –
–
0.49
≤
0.001 –
–
0.48
≤
0.001 –
–
After adjustment for age, BMI and WC
SBP (mmHg)
0.08 0.357 –0.03 0.753 –0.04 0.624 –0.13 0.132 –0.00 0.968 –0.10 0.129
DBP (mmHg)
0.12 0.185 0.03 0.757 0.06 0.476 –0.05 0.589 0.07 0.270 –0.04 0.526
HR (beats/min)
0.13 0.153 –0.03 0.706 –0.00 0.996 –0.12 0.190 0.13 0.047 –0.08 0.202
CO (l/min)
–0.01 0.933 0.04 0.696 –0.09 0.317 0.01 0.950 0.02 0.788 0.03 0.588
TPR (mmHg.s/ml)
–0.00 0.963 0.07 0.432 0.10 0.258 –0.05 0.591 –0.02 0.812 –0.00 0.965
Cwk (ml/mmHg)
–0.16 0.075 0.05 0.588 –0.06 0.535 0.09 0.329 –0.10 0.119 0.11 0.095
C-R PWV (m/s)
0.05 0.656 0.01 0.911 0.09 0.444 0.14 0.279 0.15 0.071 0.07 0.408
C-P PWV (m/s)
0.06 0.585 –0.06 0.567 –0.17 0.199 0.29 0.025 0.04 0.588 0.09 0.246
HDL-C (mmol/l)
0.14 0.135 0.02 0.851 0.05 0.575 –0.05 0.551 0.13 0.035 0.04 0.523
LDL-C (mmol/l)
–0.02 0.810 0.07 0.441 0.05 0.607 0.07 0.441 –0.01 0.880 0.05 0.444
TG (mmmol/l)
–0.02 0.860 0.11 0.220 0.08 0.382 0.14 0.117 –0.02 0.811 0.12 0.062
hs-CRP (mg/l)
0.05 0.565 0.03 0.731 0.11 0.224 0.07 0.473 0.13 0.038 0.08 0.187
Cotinine (ng/ml)
0.31
≤
0.001 –
–
0.40
≤
0.001 –
–
0.35
≤
0.001 –
–
PWV was additionally adjusted for MAP. SBP: systolic blood pressure; DBP: diastolic blood pressure; HR: heart rate; CO: cardiac output; TPR:
total peripheral resistance; Cwk: Windkessel compliance; C-R PWV: carotid-radialis pulse wave velocity; C-P PWV: carotid-dorsalis pedis pulse
wave velocity; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; TG, triglycerides; hs-CRP, high-sensitiv-
ity C-reactive protein; MAP, mean arterial pressure.
