Biomedical subjects
G Münch
Publications and source records attributed to G Münch.
Scintigraphic evaluation of cardiac autonomic innervation.
Alterations in cardiac autonomic neuronal function have become the focus of intense research in various cardiovascular diseases. Both single-photon emission tomography (SPECT) and the positron emission tomography (PET) imaging techniques in combination with radio-labeled neurotransmitters and receptor ligands have become available for the scintigraphic visualization of presynaptic and postsynaptic neuronal function. Several clinical studies have shown changes in tracer distribution in different clinical conditions, such as ischemic heart disease, congestive heart failure, malignant arrhythmias, heart transplantation, and in patients with diabetes. In patients with congestive heart failure, previous in vitro investigations have concentrated on the postsynaptic level of the sympathetic innervation. However, alterations in presynaptic nerve function have been demonstrated with scintigraphic investigations by decreased presynaptic tracer retention. Moreover, correlation between scintigraphic findings and clinical outcome was shown in patients with heart failure, providing important prognostic information superior to conventional risk assessment. In conclusion, scintigraphic evaluation by SPECT and PET allows functional characterization of cardiac presynaptic and postsynaptic neurons. Regional tracer uptake can be used as an index for the integrity of innervation in various diseases. Newer tracer approaches may allow the noninvasive quantification of neuronal function by PET.
Advanced glycation end-product levels in subtotally nephrectomized rats: beneficial effects of angiotensin II receptor 1 antagonist losartan.
The angiotensin II receptor 1 antagonist losartan (L) inhibited the advanced glycated end-products (AGEs) induced expression of transforming growth factor beta(1) in in vitro experiments performed on renal tubuloepithelial cells. To test the pathophysiological importance of these findings, the possible link between serum AGEs levels and angiotensin system was investigated in the model of normotensive subtotally nephrectomized rats(4/6-NX). Concentration of AGEs in serum of placebo administered 4/6-NX rats (n = 7, 1.09+/-0.09 U/l) increased slightly in comparison with sham-operated healthy controls (CTRL, n = 8, 0.94+/-0.10 U/l, p<0.02) as measured by competitive ELISA. Treatment of 4/6-NX rats with L over 12 weeks ameliorated the rise in serum AGEs concentration (1.00+/-0.12 U/l, n = 15 <0.005) almost to the level observed for CTRL. This effect was further corroborated by the observation, that the impaired renal excretion of AGEs in 4/6-NX-placebo rats (0.07+/-0.02 U/micromol creatinine) was significantly restored by L (0.09+/-0.02 U/micromol creatinine, <0.009) and resembled that of the CTRL (0.10+/-0.03 U/micromol creatinine). Administration of L to 4/6-NX rats significantly improved renal function as evaluated by a smaller rise in serum creatinine and urea concentration. In spite of the improvement in renal function, there were no differences in concentrations of transforming growth factor beta(1) in serum and in urine among the two groups. These effects were independent of blood pressure. Our data give first evidence, that long-term treatment with angiotensin II receptor 1 antagonist may exert salutary effects on AGEs levels in the rat remnant kidney model, probably due to improved renal function.