© Borgis - New Medicine 4/2003, s. 121-124
Tomasz Kornatowski1, Kornelia Kedziora-Kornatowska2, Hanna Pawluk3, Jozef Kedziora3, Leszek Szadujkis-Szadurski1, Robert Pawluk3, Jolanta Czuczejko3, Jadwiga Motyl2
The influence of perindopril on lipid peroxidation and the oxidase activity of ceruloplasmin in the blood of old age patients with primary hypertension
1 Department of Pharmacology and Therapy, L. Rydygier Medical Academy of Bydgoszcz, Poland
Head: prof. Leszek Szadujkis-Szadurski, MD, PhD
2 Department and Clinic of Geriatrics, L. Rydygier Medical Academy of Bydgoszcz, Poland
Head: dr Kornelia Kedziora-Kornatowska, MD, PhD
3 Department of Biochemistry, L. Rydygier Medical Academy of Bydgoszcz, Poland
Head: prof. Jozef Kedziora, MD, PhD
Summary
Background: The purpose of this work was to estimate oxidase activity of ceruloplasmin and lipid peroxidation processes in the blood of elderly patients with primary hypertension. Furthermore, the influence of treatment with ACEi, perindopril, on the examined parameters was determined.
Material and methods: The research was carried out on 28 patients (65-91 yrs) with primary hypertension, treated with perindopril for 6 weeks, and normotensive persons who constituted the control groups: 25 (65-96 yrs – K1) and 23 (22-41 yrs – K2). The oxidase activity of ceruloplasmin was measured in serum by Ravin´s method, and the concentration of malondialdehyde (MDA) in erythrocytes according to Placer et al. Patients with hypertension underwent an examination after 7 days and 6 weeks from the beginning of therapy.
Results: It was found that in the group of patients with hypertension, the activity of ceruloplasmin was significantly higher in comparison to the activity in the control groups (K1 and K2). The concentration of MDA in erythrocytes of patients with hypertension was significantly higher than in the control groups (K1 and K2). In patients with hypertension, after 7 days of therapy a substantial decrease in the oxidative activity of ceruloplasmin was found, but the lowest value was observed after 6 weeks of therapy. These values were significantly lower than those from the control groups.
Conclusions: The results confirm the intensification of oxidative stress in elderly patients with primary hypertension and point to the beneficial antioxidant effect of perindopril.
INTRODUCTION
Ageing and hypertension are essential factors in the risk of cardiovascular complications (1, 2). Such changes are significantly more intense in elderly patients with primary hypertension in comparison to persons of the same age but without hypertension (3, 4). In fact, an intensification of oxidative stress, which is the imbalance of pro-and antioxidative processes towards oxidation, is observed in the etiopathogenesis of both processes (5, 6). It has also been shown that reactive oxygen species play a significant role in the damage and dysfunction of vessel endothelium, and in hypertrophy and hyperplasia of cells of the vascular wall of smooth muscles (7, 8). Furthermore, it has been shown that one of the significant factors intensifying oxidative stress and also causing hypertrophy of the vascular wall and vascular contractility is angiotensin II. Angiotensin II released locally in the vascular wall plays a crucial role in the pathophysiology of hypertension (9). One of the possible action mechanisms of angiotensin converting enzyme inhibitors, apart from decreasing the level of angiotensin II and increasing the level of bradykinin, is an influence on oxidative stress in vessels. Research carried out by many authors has evaluated the antioxidative characteristics of various angiotensin convertase inhibitors by way of the influence on the activity of key cell antioxidative enzymes (superoxide dismutase, catalase, glutathione peroxidase), or the level of other antioxidants and lipid peroxidation products. However, such an influence on the activity of ceruloplasmin has not been evaluated (10, 11, 12).
The aim of this work was to evaluate the oxidase activity of ceruloplasmin and the process of lipid peroxidation in the blood of elderly patients with primary hypertension. In addition, the influence of treatment with angiotensin convertase inhibitor, perindopril, on the examined parameters was determined.
MATERIALS AND METHODS
The research was carried out on 25 healthy subjects (K1) between 65-96 years of age (average 74.3 ± 4.8 years) and on 23 healthy subjects (K2) between 22-41 years of age (average 37.4 ± 8.2 years), and on 28 persons between 65-91 years of age (average 74.7 ± 8.1 years) with 1st or 2nd level primary hypertension (according to the JNC-VI criteria and WHO/ISH recommendations) (13, 14).
The clinical characteristics of the examined persons are shown in table 1.
Table 1. The clinical characteristics of the examined persons.
| Parameter | Normotensive Subjects | Essential Hypertensive Patients (EAH) |
| K1 | K2 | Perindopril | |
| Before treatment (EAH) | After treatment (EAH+P) |
| Number of subject | 25 | 23 | 28 | 28 |
| Age (y) | 74.3 ? 4.8 | 37.4 ?
8.2a | 74.7 ? 8.1 | 74.7 ? 8.1 |
| Sex: M/F | 11/14 | 9/14 | 12/16 | 12/16 |
| Smoking (yes/no) | No | No | No | No |
| Body mass index (kg/m2) | 24.1? 2.1 | 22.6 ? 3.4 | 25,3 ? 2.8 | 24.9 ? 3.6 |
| Systolic blood pressure (mmHg) | 130.4 ? 6.7 | 118.7 ? 4.6 | 168.6 ?
10.4b | 132.3 ? 6.4 |
| Diastolic blood pressure (mmHg) | 81.7 ? 8.4 | 74.6 ? 4.6 | 103.2 ?
10.4b | 84.1 ? 8.5 |
| Plasma glucose (mg/dl) | 82.7 ? 4.9 | 79.1 ? 3.7 | 85.6 ? 5.5 | 88. 4 ? 6.8 |
| Plasma total cholesterol (mg/dl) | 190.6 ? 12.3 | 181.3 ? 9.6 | 196.7 ? 8.6 | 191.3 ? 10.6 |
| Plasma HDL cholesterol (mg/dl) | 43.4 ? 5.1 | 41.7 ? 7.3 | 42.6 ? 6.9 | 41.0 ? 5.6 |
| Plasma LDL cholesterol (mg/dl) | 109.3 ? 8.4 | 105.3 ? 7.2 | 110.3 ? 8.1 | 110.8 ? 9.6 |
a p <0,05 (K2 vs K1, EAH, EAH+P)
b p <0,05 (EAH vs K1, K2, EAH+P)
A permit for carrying out this research was obtained from the local Bioethics Committee in the Medical University of Bydgoszcz (KB/53/2002/), as well as written agreements from the subjects.
The criterion for the division into normotensive participants and patients with hypertension was a pressure reading of <140/90 mmHg and = 140/90 mmHg consecutively. Secondary hypertension was ruled out by means of routine diagnostics. Two days before the research pharmacological treatment was stopped in patients who were having any, after which all patients with primary hypertension were administered perindopril at a dose of 2 or 4 mg per day during a period of 6 weeks.
Blood samples were taken from the basilic vein for coagulum and heparin. Subjects with hypertension were also examined after 7 days and after 6 weeks from the start of perindopril.
The oxidase activity of ceruloplasmin was measured in the serum by Ravin´s method (15). The concentration of malon dialdehyde (MDA) in red blood cells was measured by the Placer et al. method (16).
Statistical analysis of the results was made using an automated statistical analysis package, PC SSTAT V.4.0. A value of p <0.05 was considered statistically significant.
RESULTS
In the examined groups there were no statistically significant differences between gender, BMI, smoking history, glycaemia or plasma cholesterol levels. In addition, no statistically significant differences were found between the ages of the normotensive K1 group and the group of patients with hypertension (EAH).
Both K1 and EAH groups displayed a statistically significant difference in age in comparison to the group K2 normotensive.
Statistically significant higher readings of systolic and diastolic pressure were observed in the group of patients with hypertension (EAH) before the beginning of perindopril therapy in comparison to readings after 6 weeks of therapy (EAH+P), and also in the normotensive groups K1 and K2 (table 1).
The oxidase activity of ceruloplasmin (Cp) in serum in the group of patients with hypertension was statistically significantly higher in comparison to the normotensive groups K1 and K2. After only 7 days of perindopril therapy, a statistically significant decrease in the oxidase activity of ceruloplasmin was found, and after 6 weeks of therapy the lowest activity was observed. This was not statistically significantly different from the values obtained from the younger normotensive subjects (K2) (table 2). The concentration of malondialdehyde in red blood cells in patients with hypertension (EAH) was statistically significantly higher when compared with the normotensive groups K1 and K2. After a 6-week perindopril therapy significantly lower values of MDA were found in this group (EAH+P) which, however, were not statistically significantly different from the values observed in the normotensive groups K1 and K2 (table 2).
Table 2. Concentration of malondialdehyde (MDA) and oxidase activity of ceruloplasmin in the blood of elderly patients (65-91 years) with primary hypertension before perindopril therapy (EAH), after 1 and 6 weeks of treatment (EAH+P) and in normotensive K1 subjects (65-91 years) and K2 (22-41 years).
|
Group | Parameter |
| MDA (mM/gHb) | Cp (U/L serum) |
|
EAH | 0.357?0.12a | 969.7?
166.5a |
|
EAH + P(1 week) | 0.344 ? 0.09 | 687.7 ?
281.9b |
|
EAH + P(6 weeks) | 0.278 ? 0.05b | 629.6 ?
288.9b |
|
K1 | 0.27 ? 0.11 | 898.9 ? 129.1 |
|
K2 | 0.25 ? 0.11 | 755 ? 112.0 |
a p <0,05 (EAH vs K1, K2)
b p <0,05 (EAH+P vs EHA)
DISCUSSION
An increased production of reactive oxygen species in patients with hypertension results in disorders of the physiological processes, which leads to functional and structural changes in the cardiovascular system (6, 7). Furthermore, according to Harman´s theory, oxidative stress is intensified in the process of ageing, simultaneously accompanied by a more common occurrence of primary hypertension in the elderly (17). The intensification of oxidative stress and lipid peroxidation processes at the same time were found not only in elderly subjects but also in patients with primary hypertension regardless of age (7, 9, 18).
Furthermore, in our own research we found an increased concentration of malondialdehyde, which is a lipid peroxidation marker in the elderly, and in particular in the group with accompanying hypertension. It is worth considering that both lipid peroxidation initiation and re-initiation require the presence of transition metal ions, especially iron and copper. Moreover, it was shown that in the elderly copper levels are statistically significantly higher when compared to younger persons. The main protein in extracellular fluid which contains copper and at the same time is the most important enzymatic plasma antioxidant is ceruloplasmin (12). A statistically significant increase in the oxidase activity of ceruloplasmin was confirmed in our research. Moreover, a statistically significantly higher oxidase activity of ceruloplasmin was found in the elderly with primary hypertension.
Our own observations seem to be even more interesting, as research carried out by many other authors indicates a decrease in the activity of some intracellular antioxidative enzymes with age (11, 19).
An increased activity of ceruloplasmin in the serum of the elderly, especially in these with hypertension, may be secondary to the intensified generation of reactive oxygen species and increased lipid peroxidation.
Research by many authors has shown a decreased plasma renin activity at an elderly. However, in the pathogenesis of hypertension it is not the circulating local Renin-Angiotensin-Aldosteron-System (RAA) that plays a crucial role. Also it has been concluded that in the pathogenesis of hypertension angiotensin II is not only a significant haemodynamic factor, but that non-haemodynamic action effects play a crucial role (20, 21).
One of these effects is an increased generation of reactive oxygen species, which apart from their direct destructive activity on cells and tissues, indirectly take part in many metabolic processes induced by angiotensin II (9, 22).
In our research it was observed that perindopril not only successfully lowered systolic and diastolic pressure, but also had a significant influence on the examined oxidative stress ratio.
After 6 weeks of therapy, a statistically significant decrease in the concentration of lipid peroxidation products was observed in patients with primary hypertension. Another observation was normalization of oxidase activity of ceruloplasmin up to a level which was not significantly different from that of the control group of normotensive patients´ regardless of age in the case of MDA, and that of younger normotensive patients in the case of ceruloplasmin activity. This may indicate an important role for perindopril in the reduction of oxidative stress accompanying primary hypertension and the ageing process, regardless of blood pressure.
The antioxidative characteristics of an angiotensin convertase inhibitor confirm our own previous research and that of other authors. It has been shown that convertase inhibitors stop the lipid peroxidation process and the generation of reactive oxygen species, which may influence the increase in endogenic production of nitric oxide and the improvement in the function of vessel endothelium which is induced by angiotensin II. They inhibit the oxidation of the LDL-cholesterol fraction and as a result prevent the progress of arteriosclerosis (23, 24, 25, 26).
CONCLUSIONS
Summing up, the obtained results confirm the intensification of oxidative stress in elderly patients with primary hypertension. The angiotensin convertase inhibitor perindopril not only successfully lowered blood pressure in elderly patients but also restored pro- and antioxidative homeostasis in order to increase antioxidative defenses. Considering the intensification of oxidative stress both in the ageing process and hypertension and its complications, angiotensin convertase inhibitors should constitute a particularly preferred group of hypotensive medication for elderly patients.
Piśmiennictwo
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