Ao. Obasohan et al., SODIUM-LITHIUM COUNTERTRANSPORT ACTIVITY IN NORMOTENSIVE OFFSPRING OFHYPERTENSIVE BLACK-AFRICANS, Journal of human hypertension, 12(6), 1998, pp. 373-377
Objective: To assess sodium-lithium countertransport (SLC) activity an
d erythrocyte sodium (ENa) levels in black (Nigerian) hypertensive (HT
) patients, normotensive (NT) offspring of hypertensive parents and no
rmotensive offspring of normotensive parents, and to determine if incr
eased SLC activity is related to a familiar predisposition to hyperten
sion in black subjects as in Caucasians.Method: The study was done usi
ng 60 Nigerian subjects of Edo ethnic origin in three groups of 20 eac
h: (a) untreated new HT patients at the University Teaching Hospital,
Benin City; (b)NT children of hypertensive parents (NTHT) traced home
and matched for age, sex and body mass index (BMI) with (c) NT childre
n of NT parents (NTNT). SLC activity was measured using a modified met
hod of Canessa et al 1980 and ENa assessed by flame photometry. Result
s: SLC was markedly higher in both HT patients and NTHT subjects than
the NTNT subjects. The values were 0.351 +/- 0.011 vs 0.199 +/- 0.014
mmol Li/rbc (P < 0.0001) and 0.347 +/- 0.020 vs 0.199 +/- 0.014 mmol L
i/rbc/hr (P < 0.0001), respectively. The values were not different bet
ween the HT and the NTHT group (P > 0.05). ENa was higher in the HT gr
oup than both NT groups which were similar. Values were 10.55 +/- 0.46
(HT) vs 7.78 +/- 0.62 (NTHT) (P < 0.0001) and 10.55 +/- 0.46 (HT) vs
8.62 +/- 0.47 mmol/L (P < 0.0001). There were no correlations between
either SLC activity or ENa and any of the other measured variables suc
h as age or BMT. Conclusions: SLC activity was elevated in normotensiv
e children of hypertensive subjects to a similar degree as hypertensiv
e patients and in a pattern reminiscent of that seen in Caucasians. SL
C activity may thus be associated with a familiar predisposition to hy
pertension in black subjects as in their Caucasian counterparts.