Rhythm disorders are common complications in diabetic patients, due to their enhanced sensitivity to ischaemia. However, experimental studies are inconsistent, and both higher and lower vulnerability to injury has been reported. Our objectives were to compare susceptibility to ventricular arrhythmias in rats with prolonged duration of diabetes induced by streptozotocin (45 mg/kg, i.v.), utilising two different models. Following 8 weeks, either anaesthetised open-chest rats in vivo or isolated Langendorff-perfused hearts were subjected to 30 min regional zero-flow ischaemia induced by occlusion of LAD coronary artery. In addition, cardiac glycogenolysis and lactate production were measured. In open-chest rats, 90 % of the controls exhibited ventricular tachycardia (VT) which represented 55.4 % of total arrhythmias, whereby only 19.9 % of arrhythmias occurred as VT in 44 % of the diabetic rats (P < 0.05 vs controls). Duration of VT and ventricular fibrillation (VF) was reduced from 35.5 +/- 11.1 and 224.8 +/- 153.9 s in the controls to 4.8 +/- 2.5 and 2.2 +/- 0.2 s in the diabetics, respectively (P < 0.05). Accordingly, severity of arrhythmias (arrhythmia score, AS) was also lower in the diabetics (2.0 +/- 0.38 vs 3.3 +/- 0.3 in the controls; P < 0.05). In the isolated hearts, high incidence of VF was decreased in the diabetic hearts, and although VT occurred in almost all of the diabetic hearts, the duration of VT and VF was substantially shorter (61.5 +/- 14.5 and 5.5 +/- 0.5 s vs 221.5 +/- 37 and 398.5 +/- 55 s in the controls, respectively; P < 0.05). AS was reduced to 2.9 +/- 0.12 from 4.1 +/- 0.3 in the controls (P < 0.05). Postischaemic accumulation of lactate was lower in the diabetic than in the non-diabetic myocardium (20.4 +/- 1.9 vs 29.5 +/- 2.9 micromol/l/g w.wt.; P < 0.05). These results suggest that rat hearts with chronic diabetes, despite some differences in the arrhythmia profiles between the in vivo model and isolated heart preparation, are less sensitive to ischaemic injury and exhibit lower susceptibility to ventricular arrhythmias and reduced accumulation ofglycolytic metabolites.

Current state and development of land degradation processes based on soil monitoring system in Slovakia is evaluated in this contribution. Soil monitoring system in Slovakia is consistently running since 1993 year in 5-years repetitions. Soil monitoring network in Slovakia is constructed using ecological principle, taking into account all main soil types and subtypes, soil organic matter, climatic regions, emission regions, polluted and non-polluted regions as well as various land use. The result of soil monitoring network is 318 sites on agricultural land in Slovakia. Soil properties are evaluated according to the main threats to soil relating to European Commission recommendation for European soil monitoring performance as follows: soil erosion and compaction, soil acidification, decline in soil organic matter and soil contamination. The most significant change has been determined in physical degradation of soils. The physical degradation was especially manifested in compacted and the eroded soils. It was determined that about 39% of agricultural land is potentially affected by soil erosion in Slovakia. In addition, slight decline in soil organic matter indicates the serious facts on evaluation and extension of soil degradation processes during the last period in Slovakia. Soil contamination is without significant change for the time being. It means the soils contaminated before soil monitoring process this unfavourable state lasts also at present.

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