Selected Zinc Metabolism Parameters and Left Ventricle
Mass in Echocardiographic Examination in Primary
Arterial Hypertension
Sławomir Tubek
Received: 27 July 2006 / Accepted: 20 December 2006 /
Published online: 8 May 2007
# Humana Press Inc. 2007
Abstract The basal systolic and diastolic blood pressure, body mass index, left ventricular
mass, serum and lymphocyte zinc levels, serum aldosterone, plasma rennin and
angiotensin-converting enzyme activities, sodium and potassium levels, and the total and
ouabain-dependent rate constants of zinc efflux from lymphocytes were measured in a
group of 41 individuals of both sexes (overall age 46.3±11.4 years), of which 18 were
women (48.5±7.1 years old) and 23 were men (44.7±13.8 years old). There were no
significant differences between these parameters while dividing the subjects into groups
according to sex, despite differences in weight, left ventricle mass, plasma rennin activity,
and serum aldosterone content. Only the total and ouabain-dependent rate constants of zinc
efflux from lymphocytes slightly negatively correlated to left ventricular mass, r=−0.30 to
r=−0.36. This may constitute indirect evidence of zinc deficiency in cardiomyocytes of
some hypertensive individuals with left ventricular hypertrophy.
Keywords Zinc . Zinc efflux from lymphocytes . Arterial hypertension .
Left ventricular hypertrophy
Abbreviations
Aldosterone Ald
Angiotensin-converting enzyme ACE
Body mass index BMI
Diastolic blood pressure dRR
Lymphocyte zinc Zn-l
Plasma rennin activity PRA
Biol Trace Elem Res (2007) 118:138–145
DOI 10.1007/s12011-007-0021-0
S. Tubek (*)
Faculty of Physical Education and Physiotherapy, Institute of Technology, Opole,
Prószkowska Street 76, 45-758 Opole, Poland
e-mail:
[email protected]S. Tubek
Clinic of Cardiology, Medical Academy,
Wrocław, Poland
Rate constants of zinc efflux from lymphocytes
Total ERCt-Zn
Oubain-dependent ERCos-Zn
Serum zinc Zn-s
Systolic blood pressure sRR
Introduction
Adaptation of cardiac muscle to an increased workload may result from improved
myocardial performance and/or by hypertrophy. In about half the patients with untreated
high blood pressure, hypertrophy of the left ventricle muscle was observed. Studies in
animals and human have shown that arterial hypertension brings about changes in zinc
metabolism such as redistribution of zinc within intracellular compartments. Increased zinc
in heart tissue was found in rats with spontaneous hypertension (SHR). In coronary heart
disease patients, the zinc content of myocardial tissue correlated positively with cardiac
output parameters [1–5].
Changes in zinc metabolism and its redistribution within intracellular compartments
appear in the course of arterial hypertension. These changes may result in zinc deficiency,
which in turn may impair myocardial compensatory and reconstructive processes, increase
left ventricular load, and eventually lead to left ventricular failure. There is experimental
evidence of the role of zinc in blood pressure regulation and zinc deficiency in the course of
arterial hypertension, and there is an ongoing discussion on the role of zinc supplementation
in various pathological states of the organism [4, 5]. The relationship between zinc
metabolism and heart muscle hypertrophy has not been yet established.
By affecting the rise of 1,4,5-triphosphoinositol (InsP3) and intracellular calcium
contents, elevated zinc in myocardium cells can also increase myocardium tension and
hypertrophy. Increased zinc content in heart muscle of SHRs was observed as early as the
prehypertensive period, which could be explained in terms of genetic determinants [4–8].
It was experimentally proven that greater heart muscle load influences gene expressions
that are related to increased cellular demand for zinc, which is involved in transcription,
translation, and enzymatic and structural protein syntheses [9–11]. Increased accumulation
of calcium and zinc was reported in hypertrophic cardiomyopathy in hamsters [12]. Higher
zinc content is thought to be connected to intensified intracellular damage repair
mechanisms that are the result of genetically determined changes in structure of proteins
of cardiomyocytes [12]. The mutations could concern sites where zinc is being incorporated
and disrupt the zinc-fingers forming process, which would cause lower stability of proteins
and increased tendency to proteolysis [13].
The rise of heart load also causes a rise of activity of antioxidant enzymes, including zincdependent
Cu/Zn superoxide dismutase (SOD) [14]. Inappropriate activation of such enzymes
would result in a rise of oxidative stress damaging cardiomyocytes. It was revealed that free
radicals per se stimulate mobilization of zinc ions in cardiomyocytes [15–17]. Thus, it can be
assumed that the greater left ventricle load itself would elevate the zinc ions content in
cardiomyocytes, at least for higher demand for the functions of Cu/Zn SOD. Thus, left
ventricle muscle hypertrophy occurrence in some patients suffering from arterial hypertension
can be linked with inefficient compensating mechanisms of cardiomyocytes towards the rise
of hemodynamic load, resulting from structural and/or functional changes of structural,
contractile whether enzymatic proteins. These intensified processes – both compensating and
repairing – require larger amounts of intracellular zinc [18].
Zinc and Left Ventriclular Hypertrophy 139
The main aim of this work is to study the relationship between the echocardiographic
parameters of left ventricle and selected zinc metabolism parameters in patients suffering
from primary arterial hypertension.
Materials and Methods
The study group consisted of 41 individuals of average age 46.3±11.4 years. Of these, 18
were women (age 48.5±7.1 years) and 23 were men (age 44.65±13.77 years). All the
participants were made aware of the aim of the study and gave their consent for
participation.
The subjects were tested for basic systolic and diastolic blood pressure, lymphocyte zinc
and the total and ouabain-dependent rate constants of zinc efflux from lymphocytes, body
mass index, left ventricular mass, the serum levels of zinc and aldosterone, plasma rennin
activity, angiotensin-converting enzyme, sodium and potassium. The blood samples were
drawn from the antebrachial basilic vein, between 0800 and 1000 hours in the morning.
Except for the concentrations of serum and lymphocyte zinc, the entire research was
performed in the Isotopic Laboratory of the Department and Clinic of Cardiology, Medical
Academy, Wrocław, Poland.
The separation of lymphocytes from the peripheral blood was conducted by Boyum’s
method using Noworolska’s modification [19, 20]. The rate constants of zinc efflux were
measured following the method of Heagerty et al. for measurement of the corresponding
rate constants of sodium ions efflux [21]. After separation, the lymphocytes were rinsed
three times with 0.1 M MgCl2 and suspended in 2 ml of the same solution for incubation
for 30 min with 65ZnCl2 with 0.2 μCi activity at 37°C. After incubation, the lymphocytes
were again rinsed three times as before and the sample was divided into two parts. Both
samples were added with equal volumes of 0.1 M MgCl2 and one of the samples was added
with 0.1 mg (0.1 mmol) of ouabain. The activity of the samples was measured at times t=0
and t=60 min. The ouabain-dependent outflow rate constant was obtained by subtracting
the ouabain independent from the total rate constant.
The concentrations of serum and lymphocyte zinc were measured using a Perkin-Elmer
atomic absorption spectrometer model 5000 following literature procedures [22].
Echocardiographic measurements were made with the use of Sonoline 200S (Siemens)
and SIM 1200 Plus (Easotebiomedica). Left ventricular mass was calculated with Devereux
method [23].
The statistical calculations were made using the Statistica v.51G software for Windows.
Student’s t test was used to establish the statistical significance of differences between
samples in case of normal distribution, whereas the Kolmogorow–Smirnow test was used if
the distribution was not normal. In all cases, the level of significance was set at p