Biomedical subjects

A F Rump

Publications and source records attributed to A F Rump.

41 records · Page 3Linked to original sources

PubMed1993

Effects of propranolol, pindolol and carteolol on acute regional myocardial ischemia in isolated rabbit hearts.

Catecholamines play a major role during initiation and propagation of myocardial ischemia (MI). Therefore their influence on the size of an acute regional MI was investigated in isolated, coronary ligated rabbit hearts during electrical pacing at different rates (Langendorff, constant pressure: 70 cm H2O, Tyrode solution, Ca2+ 1.8 mmol/l). MI was quantified from NADH-surface-fluorescence-photography. After coronary occlusion the stimulation-rate was increased stepwise from 180 beats/min to 300/min. Experiments were performed in hearts of control and reserpinized rabbits (reserpine 7.0 mg/kg i.p. 24 h before preparation). Hearts of control animals were submitted to beta-blockade by propranolol (10(-8) mol/l) or the partial agonists pindolol (10(-6) mol/l) or carteolol (10(-6) mol/l). In untreated control hearts MI was significantly enlarged with increasing heart-rate (p < 0.05). At 300/min MI was doubled as compared to that observed at 180/min. In hearts of reserpinized animals this effect was absent (p > 0.05). Moreover, in control hearts the growth of MI could be prevented by beta-blockade with propranolol, pindolol or carteolol (p > 0.05), however, these hearts became insufficient as indicated by an increase in left ventricular enddiastolic pressure. Therefore we conclude that the pacing-rate dependent growth of MI seems not to be primarily related to myocardial left ventricular pressure nor to the heart rate. Nevertheless the growth of MI is strictly related to the release of catecholamines and might be caused by oxygen free radicals generated from noradrenaline by autoxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

PubMed1993

Effect of amrinone and milrinone on myocardial ischemia extent and infarct size in isolated rabbit hearts.

UNLABELLED: The effect of inotropics on myocardial ischemia is difficult to predict, since inotropics may influence the determinants of myocardial O2-demand and O2-supply differently. Several phosphodiesterase-inhibitors have been reported to possess antiischemic properties related in vivo to their hemodynamic and O2-sparing effects. The effects of amrinone (CAS 60719-84-8) (10(-6) mol/l or 5 x 10(-5) mol/l) or milrinone (CAS 78415-72-2) 10(-5) mol/l) on myocardial ischemia extent and infarct size were compared in isolated electrically paced rabbit hearts (Langendorff, constant pressure: 70 cm H2O, Tyrode solution, Ca2+ 1.8 mmol/l). Myocardial ischemia was induced by left coronary artery branch occlusion and quantitated from epicardial NADH-fluorescence photography. Infarct size was determined by Evan's blue dye and nitroblue-tetrazolium staining and planimetry. At low concentration (10(-6) mol/l), amrinone had no significant influence on left ventricular pressure or coronary flow (p < 0.05) and epicardial NADH-fluorescence area or infarct size were not significantly affected compared to controls (p > 0.05). Amrinone (5 x 10(-5) mol/l) or milrinone (10(-5) mol/l) significantly increased left ventricular pressure (+10%, p < 0.05) and coronary flow (+30, 40%, p < 0.05) to a similar extent. Concomitantly, both agents similarly reduced epicardial NADH-fluorescence area (-25%, p < 0.05) and infarct size relative to the area at risk or ventricle size compared to controls (p < 0.05). CONCLUSION: amrinone or milrinone possess comparable antiischemic effects in isolated rabbit hearts that seem to be related to coronary dilator activity of these agents.

Amrinone↗

PubMed1991

Intestinal absorption of gabapentin in rats.

Gabapentin (1-aminomethyl-)cyclohexaneacetic acid, Gö 3450, CI-945; CAS 60142-96-3) is a new gamma-aminobutyric acid (GABA) analogous compound that has shown an anticonvulsive effect as well as low toxicity in preclinical and clinical studies. The substance is well absorbed after oral administration and penetrates the blood-brain barrier. The aim of experiments was to study the mechanism of intestinal absorption, the relationship between the absorption rate and the applied concentration and whether the absorption rate differs between different parts of the intestine. For this purpose, isolated intestinal segments of rats (everted sac preparations) were used. Due to the fact that gabapentin is not metabolized in the intestine, its concentration in the mucosal and serosal compartments could be determined by scintillation counting of 3H-gabapentin. The results showed that gabapentin was absorbed by simple diffusion because neither indications for an uphill nor for a carrier-mediated transport could be demonstrated. The absorption rate was linearly related in the concentration range from 0.001 to 100 mmol/l. There was no significant difference between the absorption rate in the three parts of the small intestine at 1 and 10 mmol/l, while the absorption rate was significantly (p less than 0.01) lower in the colon.

Acetates↗

PubMedDate not supplied

Functional and antiischaemic effects of the phosphodiesterase inhibitor levosimendan in isolated rabbit hearts.

UNLABELLED: Several phosphodiesterase inhibitors have been reported to possess antiischaemic properties by improving myocardial oxygen demand/supply balance. Levosimendan is a new phosphodiesterase inhibitor with calcium-sensitizing properties. We investigated the functional and antiischaemic properties of levosimendan in isolated electrically-driven rabbit hearts (Langendorff, constant perfusion pressure: 70 cm H2O, Tyrode solution, Ca++ 1.8 mmol/l, 37 degrees, 200 beats/min.). Acute regional myocardial ischaemia was induced by ligature of a circumflex artery branch and quantified from epicardial NADH-fluorescence photography. RESULTS: The left ventricular pressure was similarly enhanced by levosimendan 10(-7) M or 5 x 10(-6) M (+15%) (P < 0.05). The global coronary flow was increased more markedly by levosimendan 5 x 10(-6) M (+35-50%) compared to 10(-7) M (+25%) (P < 0.05). The relative coronary flow (= global coronary flow/pressure-rate-product) was significantly enhanced only by levosimendan 5 x 10(-6) M (+20-35%) (P < 0.05), but not by levosimendan 10(-7) M (+10-15%) (P > 0.05). Epicardial NADH-fluorescence area and intensity were significantly diminished by levosimendan (-20%) (P < 0.05), and there was no significant difference between myocardial ischaemia reduction by levosimendan 10(-7) M and 5 x 10(-6) M (P > 0.05). CONCLUSION: Levosimendan is an inotrope with coronary dilator activity, showing antiischaemic effects in isolated rabbit hearts. These may be caused by (1) phosphodiesterase-inhibition and improvement of myocardial perfusion and/or (2) by oxygen-sparing effects, related to calcium sensitization of myofilaments, particularly at lower concentrations associated with a lower coronary dilator activity.

Animals↗

PubMedDate not supplied

Anti-infective catheters: novel strategies to prevent nosocomial infections in oncology.

Intravenous access contributes significantly to the therapeutical success and to the comfort of oncologic patients. The highest risk for bloodstream infections, however, is vascular catheter-mediated. In oncology high mortality is associated with Pseudomonas aeruginosa, Candida albicans and Staphylococcus aureus sepsis. Besides established hygienic measures, the coupling or incorporation of antimicrobial substances to or into catheter materials may be a suitable way to prevent the development of catheter-associated infections. Here we present a risk- benefit evaluation of different models of antimicrobial catheter coated with silver, antiseptics or antibiotics. The controversial reports on clinical efficacy and the potential of adverse reactions due to silver and antiseptic coated catheters are discussed. The microbiological, pharmaceutical and physicochemical backgrounds of different types of coating are discussed in detail. Incorporation of antimicrobial agents into long-term silicon catheters providing a slow release of those substances through the external and internal surfaces of catheters may be the most effective technological innovation for reducing biomaterial-mediated nosocomial infections.

Anti-Infective Agents↗