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The ischaemic vulnerability of the heart of spontaneously hypertensive rats (SHR) is enhanced after feeding an alpha-linolenic acid (LNA) enriched diet. Because oxygen radical-induced reactions (e.g. lipid peroxidation) are involved in the ischaemic damage, an increased susceptibility of the SHR heart to such damaging reactions might be the reason. As a sign of the enhanced susceptibility to lipid peroxidation of LNA-fed SHR, we found (measured as TBARS) higher plasma and heart lipid peroxide levels (3.84 +/- 0.50 micromol/l vs 2.98 +/- 0.78 micromol/l and 507 +/- 127 nmol/g prot. vs 215 +/- 80 nmol/g prot., respectively) after feeding LNA. Using Fe2+/Vit. C to induce lipid peroxidation in myocardial tissue homogenates, we demonstrated the enhanced susceptibility to lipid peroxidation of the LNA-fed SHR heart (68 +/- 12 nmol/min x g prot. vs 40 +/- 8 nmol/min x g prot.) also in vitro. The myocardial enrichment of n-3 polyunsaturated fatty acids (PUFA) resulting in a higher peroxidation index (PI 227 vs. 170) and the loss in myocardial activities of the antioxidative enzymes (SOD: 76 +/- 24 U x 10(3)/g prot. vs 235 +/- 150 U x 10(3)/g prot.; GSH-Px: 32 +/- 5 U/g prot. vs 110 +/- 30 U/g prot.) by feeding LNA could be the cause of the increase in myocardial susceptibility to lipid peroxidation of PUFA supplemented SHR.

The effect of prenatal hypoxia on the development of the beta-adrenoceptor during the ontogenesis of rats was investigated. It was shown that the offspring from hypoxic dams, in comparison with normoxic control animals, exhibited alterations of the density (Bmax) of the myocardial beta-receptors and of the catecholamine levels in heart tissue during development. The results suggest that the beta-adrenoceptor changes might be involved in the phenomenon of enhanced sensitivity of prenatal hypoxic animals to catecholamines in adult age.

In this study, the effect of prenatal hypoxia on the catecholamine sensitivity of the offspring of pregnant rats was investigated. The offspring from hypoxic animals showed after treatment with isoproterenol in adult age a distinctly more pronounced decrease of protein content and enzyme activities in heart tissue as well as a significantly higher elevation of enzyme activities in blood plasma as compared with the offspring from normoxic rats. These results suggest a long-lasting enhancement of catecholamine sensitivity after prenatal oxygen deficiency.

The irreversible loss of activity of the sarcolemma-localized beta-receptor-adenylyl cyclase system (beta-RAS) in myocardial ischemia is a well documented phenomenon. Alterations in the sarcolemma (SL) induced by reactive O2 species could be responsible for this loss. Therefore the influence of oxidation of SH-groups and lipid peroxidation induced by Fe2+/Vit. C on the beta-RAS activity was studied. During incubation of SL with Fe2+/Vit. C a transient enhancement followed by a continuous loss of the beta-RAS activity (isoprenaline-, NaF-, Gpp(NH)p-, forskolin-stimulated and basal activity) was observed. In contrast there occurred a continuous loss of SH-groups and lipid peroxidation, beginning immediately after the start of incubation. Loss of SH-groups and lipid peroxidation as well as changes in the beta-RAS did not take place in the presence of the antioxidant t-Butyl-4-hydroxyanisole (BHA) or the Fe(2+)-chelator EGTA. In view of the known ischemia-induced formation of reactive O2 species our results show that these powerful oxidants could contribute to the modulation of the beta-RAS during myocardial ischemia.

The present study utilized a cultured adult myocardial cell model to examine the arachidonic acid metabolism under different cell-damaging and normoxic conditions. Cell injury was caused by short-time hypoxia, calcium ionophore A 23187-triggered cell-damage under hypoxia and cell disruption by freezing and thawing. The current study demonstrates that under the cell-damaging conditions cultured adult heart myocytes resemble myocardial cells under normoxic conditions in metabolizing arachidonic acid into triacylglycerols and phospholipids as the major route (a), in formation of ETYA-inhibitable indomethacin-resistant lipid metabolites in minor amounts (b) and in being independent of calcium overload in the metabolic pathways of arachidonic acid metabolism (c). The ETYA-inhibitable components were resolved by HPLC. There was no evidence in formation of lipoxygenase products. The results were supported by negative hybridisation experiments of the total mRNA isolated from adult myocardial cells with a cDNA probe of a red-cell-specific lipoxygenase mRNA. We conclude from these observations that cell injury does not result in expression of lipoxygenase activities in heart myocytes.

In this study the influence of long-term feeding of an alpha-linolenic acid (LNA) enriched diet on the sensitivity of SHR to catecholamine-induced myocardial injury was investigated. An enhanced ischemic vulnerability after LNA supplementation was observed as indicated both by a marked decrease of enzyme activities in the myocardium and by a pronounced elevation of plasma enzymes. Distinctly higher TBARS levels in heart tissue and plasma of LNA rich fed SHR suggest that an exaggerated lipid peroxidation might contribute to the increased ischemic vulnerability. Non-enzymatic lipid peroxidation is favoured by a feeding-provoked enrichment in highly unsaturated fatty acids in tissue phospholipids. Under such conditions of enhanced substrate availability for radical-induced lipid peroxidation an increased requirement for antioxidants can be assumed which might not sufficiently be met by tocopherol-supplementation in SHR because of their known defects in antioxidative defense mechanisms.

The plasma activities of LDH and ASAT isoenzymes as well as of DP IV were studied in patients with essential hypertension and related to blood pressure, haemodynamic indicators of latent heart failure and to ischaemic heart risk indicators. Patients with elevated systolic or diastolic blood pressure showed significantly increased activities of ASAT m. In hypertensives with elevated pulmonary artery pressure markedly increased activities of ASAT, ASAT m, LDH M and DP IV could be observed. Distinctly increased activities of ASAT, ASAT m, LDH M and DP IV were also found in patients with elevated plasma cholesterol. The results obtained suggest that changes of LDH and ASAT isoenzymes as well as of DP IV indirectly reflecting alterations in organ metabolism might provide useful additional information with respect to uncovering hypertension-linked complications.

The concentration of thiobarbituric acid reactive substances (TBARS) formed as a result of lipid peroxidation and prostanoid metabolism was measured in the plasma of patients with coronary or peripheric atherosclerosis. From the results conclusions were deduced to the function of reactive O2-species in the atherogenesis. We found in plasma of patients with coronary as well as with peripheric atherosclerosis increased TBARS concentrations dependent on the dimension of atherosclerosis as an index of activation of reactive O2-species formation. The TBARS concentration correlated with the cholesterol and LDL-cholesterol concentration in plasma.

The serum concentration of thiobarbituric acid reactive substances (TBARS), which can be used in the characterization of O2-radical metabolism, was analyzed in patients with myocardial infarction in the acute phase, 10-14 days, 1 month, and 6 months after infarction, and compared with the TBARS concentration of a healthy group and a group with atherosclerosis. After myocardial infarction we found increased TBARS concentration at all moments of investigation in comparison with the healthy and atherosclerosis groups. Maximum concentration was found 10-14 days after infarction, afterwards the TBARS concentration decreased, without however attaining the values which we found in the comparison groups. The increased TBARS concentration 6 months after myocardial infarction demonstrates a manifestation of disturbances in the O2-radical metabolism. Such disturbances may be regarded as a high-risk factor to the cardiovascular system.

The purine oxidation via XOD formed from XDH in ischemia in an oxidative or proteolytic way is regarded as a source of reactive O2- species. Usually the XOD/XDH ratio is measured to determine the capacity of tissues to form these important inducers of cell damage. But we found that it is difficult to fix the in vivo XOD/XDH ratio, because preparation and measurement time and conditions (absence or presence of SH-protecting agent, of cations) influenced this ratio. A supposed additional proteolytic increase of XOD during the killing procedure could not confirmed.

Lipid peroxidation as well as enzyme and isoenzyme activities in heart and blood plasma were investigated in 8- and 20-week-old SHR after administration of 40 mg/kg body weight isoproterenol in comparison to WKY rats in order to examine the susceptibility of the hearts of hypertensive animals towards catecholamine-induced damage. The mortality of SHR after isoproterenol application was distinctly higher as compared with WKY rats. SHR showed significantly higher concentrations of lipid peroxides in the myocardium after isoproterenol. Distinctly higher plasma activities of CK, isoenzymes of LDH and ASAT as well as markedly lower CK activities in the myocardium point to an enhanced sensitivity of SHR to catecholamine-induced damage. The results obtained in this study favour the suggestion that an exaggerated nonenzymatic and perhaps enzymatic formation of peroxidized lipids in the myocardium might contribute to this increased sensitivity.

In vitro studies have demonstrated that free radicals generated by Fe2+/Vit. C alter the beta-RAS function. SH-oxidation, peroxidation of sarcolemmal lipids and reaction of aldehydes (formed by lipid peroxidation) with the beta-RAS may contribute to this effect. In order to clarify the role of these reactions in respect to their ability to alter the beta-RAS function the time course of SH-oxidation, lipid peroxidation and formation of aldehyde reaction products has been studied. As result it is shown that SH-oxidation is nearly completed within 5 minutes and lipid peroxidation within 30 minutes after exposure to Fe2+/Vit. C. During this time period there was only a very small amount of aldehyde reaction products detectable. Therefore SH-oxidation and/or lipid peroxidation should be responsible for the activity loss of the beta-RAS.

It is demonstrated on the heart tissue of rats that the extent of lipid peroxidation following induction of radical-forming mechanisms is correlated with the Vit. E concentration of the heart. When incubated with Fe2+/Vit.C, the heart tissue of normotensive (WKY) and hypertensive rats receiving Vit. E supplementation (SHR + Vit. E), consistently with their higher Vit. E concentration, reacted with a lower lipid peroxidation than the heart tissue of SHR. Considering the importance of lipid peroxidation as a damaging mechanism at ischemia, the lower Vit. E concentration in the hearts of SHR should be responsible for the lower tolerance to ischemia in comparison to WKY.

Precursor mRNA (pre-mRNA) was extracted from erythroid enriched bone marrow cells of the rabbit by the methods of Georgiev and Mantieva modified by Markov and Arion and of Holmes and Bonner, respectively. Density gradient centrifugation, base analysis and the effects of alpha-amanitin and actinomycin D on the synthesis of the cellular RNA showed signs of degradation in the rRNA-free 85 degrees C-fraction of the preparation according to Georgiev and Mantieva and a substantial rRNA contamination of the 65 degrees C-fraction. This RNA-fraction as well as the total RNA-preparation extracted according to Holmes and Bonner was purified from rRNA by affinity chromatography on poly(U)-Sepharose. Poly(A)+-RNA of all size-classes, among it a substantial amount of high molecular weight RNA (greater than 45 S), was isolated by this purification procedure. Especially the extraction according to Holmes and Bonner yields high molecular weight material but the critical step of this procedure often resulting in degradation of the RNA is the DNase treatment of the heavily DNA-contaminated total RNA-preparation either due to RNase contamination of the DNase or to the existence of RNase in the less intensive deproteinized RNA. The investigated cellular system is characterized by a very intensive rRNA synthesis which is typical for cells in the early stages of hematopoiesis. In contrast to investigations with purified RNA-polymerases and subcellular systems, but in accordance with data of in vivo experiments, alpha-amanitin inhibits both the pre-mRNA and the pre-rRNA synthesis.

In endomyocardial biopsies from 67 patients with various chronic heart diseases (small vessel disease, cardiomyopathies and hypertensive heart disease) the isoenzymes of Lactate Dehydrogenase (LDH) and Aspartate Aminotransferase (ASAT) and Glycogen Phosphorylase (GP) were investigated and compared with a reference group without actual morphological and functional evidence of chronic heart disease. The analyzed parameters showed characteristical alterations dependent on the degree of hypertrophy of the heart muscle cells and the stage of the disease as assessed by left ventricular enddiastolic pressure (LVEDP), ventricular kinetics, left ventricular heart mass (LVHM) and exercise electrocardiogram. The biochemical alterations found reflect different metabolic situations in the myocardium and could be useful as additional information for assessing the severity of the disease.