RESUMEN
The risk of developing chronic hypertension increases with age. Among others factors, increased oxidative stress is a well-recognized etiological factor for the development of hypertension. The co-occurrence of oxidative stress and hypertension may occur as a consequence of a decrease in antioxidant defense system activity or elevated reactive oxygen species generation. Glutathione is a major intracellular thiol-disulfide redox buffer that serves as a cofactor for many antioxidant enzymes. Glutathione-related parameters are altered in hypertension, suggesting that there is an association between the glutathione-related redox system and hypertension. In this review, we provide mechanistic explanations for how glutathione maintains blood pressure. More specifically, we discuss glutathione's role in combating oxidative stress and maintaining nitric oxide bioavailability via the formation of nitrosothiols and nitrosohemoglobin. Although impaired vasodilator responses are observed in S-nitrosothiol-deficient red blood cells, this potential hypertensive mechanism is currently overlooked in the literature. Here we fill in this gap by discussing the role of glutathione in nitric oxide metabolism and controlling blood pressure. We conclude that disturbances in glutathione metabolism might explain age-dependent increases in blood pressure.
Asunto(s)
Glutatión/metabolismo , Hipertensión/metabolismo , Animales , Glutatión/fisiología , Glutatión Peroxidasa/metabolismo , Glutatión Transferasa/metabolismo , Humanos , Hipertensión/fisiopatología , Óxido Nítrico/metabolismo , Estrés Oxidativo , VasodilataciónRESUMEN
The purpose of this study was to analyze glutathione antioxidant defense system in elderly patients treated for hypertension. Studies were carried out in the blood collected from 18 hypertensive and 15 age- and sex-matched controls, all subjects age over 60. Hypertensives were on their usual antihypertensive treatment at the time of blood collection. The concentration of glutathione (GSH) in whole blood and activities of glutathione peroxidase (GPx-1), glutathione transferase (GST), and glutathione reductase (GR) in erythrocytes were measured. The data from patients and controls were compared using independent-samples t test. P value of 0.05 and less was considered statistically significant. We observed increased glutathione-related antioxidant defense in treated hypertensive elderly patients (HT) when compared with healthy controls (C). Mean GSH concentration was significantly higher in HT when compared with C: 3.1 ± 0.29 and 2.6 ± 0.25 mmol/L, respectively, P < 0.001. Mean activity of GR was significantly higher in HT group if compared with C: 83.4 ± 15.25 U/g Hb versus 64.2 ± 8.26 U/g Hb, respectively, P < 0.001. Mean activity of GST was significantly higher in HT group compared with C: 3.0 ± 0.60 mmol CDNB-GSH/mgHb/min and 2.6 ± 0.36 mmol CDNB-GSH/mgHb/min, respectively, P < 0.05. No difference in GPx activity was observed between two groups. These results show that glutathione-related antioxidant defense system was enhanced in elderly hypertensive patients treated for their conditions. This suggests important role of glutathione system in blood pressure regulation. Alterations in concentration and activity of antioxidants observed during antihypertensive medication are likely to be related to the effect of the treatment on NO bioavailability.
Asunto(s)
Antihipertensivos/uso terapéutico , Glutatión/sangre , Hipertensión/tratamiento farmacológico , Factores de Edad , Anciano , Anciano de 80 o más Años , Biomarcadores/sangre , Presión Sanguínea/efectos de los fármacos , Estudios de Casos y Controles , Femenino , Glutatión Peroxidasa/sangre , Glutatión Reductasa/sangre , Glutatión Transferasa/sangre , Humanos , Hipertensión/sangre , Hipertensión/fisiopatología , Masculino , Polonia , Regulación hacia Arriba , Glutatión Peroxidasa GPX1RESUMEN
BACKGROUND: Among the tissues of humans the highest level of selenium (Se) is found in the kidney and the lowest in the muscle. The Se level in tissues is age-dependent. AIM: To measure the Se level in kidney, liver and heart of newborns and infants who were born in different periods of pregnancy and died of various diseases. SUBJECTS: Tissues obtained from 49 infants deceased at 1 day to 2.5 months of age. Forty-five of them were premature infants born between 23 and 36 weeks of pregnancy, four were born at term. RESULTS: Se levels in kidney and heart (but not liver) increased gradually with the duration of pregnancy. Positive and significant correlations were found between the weeks of pregnancy and Se levels in kidney (r=0.433, P=0.023) and heart (r=0.313, P=0.030). In the total group, the mean Se levels in the kidney (185+/-64.7 ng/g wet weight) and liver (177+/-59.8 ng/g) were two times higher than those in the heart (90.5+/-33.7 ng/g). In this study, the Se levels in kidney and liver were from 2.5 to 1.2 times lower than the values found in our previous study for healthy adult victims. In the heart, the Se levels were similar in infants and adults. No significant differences were found in the mean Se levels in the various tissues in infants who died due to respiratory distress syndrome, congenital heart disease, other diseases and the group as a whole. The low levels of Se in the tissues studied by us, as compared with data from other countries, are probably due to lower Se intake by pregnant women in Poland. CONCLUSIONS: This study demonstrates that Se level in kidney and heart, but not in liver, increases with the progress of pregnancy. The Se level in kidney and liver is two times higher compared with heart and significantly higher than in adult subjects.
Asunto(s)
Riñón/química , Hígado/química , Miocardio/química , Selenio/análisis , Femenino , Edad Gestacional , Humanos , Lactante , Recién Nacido , Masculino , Distribución TisularRESUMEN
The authors obtained tissue samples taken at autopsy from 46 healthy individuals killed in accidents and from 75 corpses of victims of various diseases to analyze selenium levels. The per-weight-unit basis of selenium levels (all expressed as ng/gm wet tissue) in tissues decreased in the following order: kidney (469) > liver > spleen > pancreas > heart > brain > lung > bone > skeletal muscle (51). The highest proportion of body selenium was found in skeletal muscles (27.5%); much less selenium was found in bones (16%) and blood (10%). In the tissues of cancer corpses, the selenium levels were much lower than levels in controls. The lowest selenium levels were found in the livers of alcoholics. Tissue selenium levels found in the study were significantly lower than levels reported in Japan, United States, Canada, and other countries. The low selenium levels in the tissues of Polish residents result from inadequate selenium levels in the soil. The authors used selenium levels in tissues to calculate the amount of selenium in humans in Poland (i.e., approximately 5.2 mg). This level was similar to levels found in New Zealand (i.e., 3.0-6.1 mg), but it was lower than the mean level found in Germany (i.e., 6.6 mg) and in the United States (i.e., 13.0-20.3 mg).