Biomedical subjects

A Aminalai

Publications and source records attributed to A Aminalai.

5 recordsLinked to original sources

PubMed1993

Interrelations between electrical and biochemical processes in ischemic porcine livers at low temperature.

Recently it has been shown that during liver ischemia at 25 degrees C the presence of glycogen, by supporting glycolytic supply, not only retards ATP decay but also leads to a corresponding delay of the rise of the electrical impedance of the ischemic organ. A sudden rise of impedance during ischemia is supposed to indicate the closure of gap junctions. Although similar effects on energy state do exist at low temperature, the impact of glycogen on the electrical impedance under storage conditions has still to be evaluated. Therefore, in a model with protected porcine livers, we examined the intraischemic effects of a preischemic glucose and potassium feeding on impedance changes, lactate production and ATP-content at a storing temperature of 5 degrees C. Impedance was measured both in the low frequency alpha- and the higher frequency beta-dispersion range. In addition, the same parameters were determined in a group of unprotected livers. In this group all animals had received glucose and potassium orally prior to ischemia. Whereas in case of preischemic glucose feeding the rise of impedance in the range of the beta-dispersion (e.g. 5kHz) roughly coincided with the exhaustion of ATP, the corresponding impedance changes in the protected group without a glucose premedication only occurred when glycolysis had already stopped and ATP had reached basal values for some hours. In contrast, in the alpha-dispersion range the impedance changes in the latter group just began at the time when ATP became exhausted and lactate production ceased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗

PubMed1992

Morphological investigation of the porcine liver directly following preservation with Euro-Collins, University of Wisconsin and Bretschneider's HTK solution.

In order to study perfusion effects of different liver preservation methods on liver structure, porcine livers were perfused with either Bretschneider's HTK (Histidine Tryptophane Ketoglutarat) solution, Euro-Collins (EC) solution or University of Wisconsin solution (UW) according to the respective recommended protocols. Subsequently, together with a group of unprotected livers, all organs were examined by light and electron microscopy including computer assisted morphometry. The width of the space of Disse, the continuity of endothelial cells and the ultrastructure of the hepatocytes were not impaired after cold perfusion with any of the 3 solutions. However, we found considerable differences between the groups with respect to removal of blood cells from liver sinusoids. Livers flushed according to the HTK-protocol had the lowest residual blood cell content followed by the livers of the EC- and the UW-group. Centrilobular regions of the liver lobules were generally better washed free of blood than periportal zones. Computer assisted morphometry did not reveal any significant difference between the size of hepatocytes of EC-, UW- and HTK livers. Only the hepatocytes of normothermic control livers (biopsy samples) were 10% larger than hepatocytes of cold flushed groups. None of the protective perfusion protocols showed structural signs of perfusion injury.

Adenosine↗

PubMed1991

Influence of tissue acidification and halothane anesthesia on hepatic electrical and biochemical properties during ischemia.

In order to further corroborate the recent findings on liver ischemia after perfusion with solutions containing an additive of heptanol, that the intraischemic loss of cell-to-cell communication in protected livers can be detected by electrical impedance measurement (1), we tried to induce uncoupling in porcine liver by tissue acidification applying acidified protective solutions. Moreover, the effects of preischemic inhaling of high concentrations of the decoupling anesthetic halothane were examined in unprotected ischemic livers (2-5). Electrical impedance, biochemical analyses, and pH measurements were applied in parallel. In addition, typical time courses of impedance parameters of unprotected liver and skeletal muscle were compared, because the latter is devoid of gap junctions. In spite of overlapping side-effects of the respective uncoupling measure, the results suggest that the loss of cell-to-cell communication in the liver is associated with measureable effects on the electrical impedance.

Acid-Base Equilibrium↗

PubMed1990

Heptanol effects on protected livers.

Heptanol, an agent known for inducing closure of gap junctions in a variety of organs, was used to evaluate the influence of uncoupling on the electrical impedance of livers during ischemia. Heptanol was added to a modified HTK solution or to Belzer's UW-CSS solution. Livers of swine were then perfused for 8 min with either one of the solutions containing heptanol or a solution devoid of this additive. During the following ischemia the phase angle of impedance at 5 kHz, pH and different biochemical parameters were determined. Heptanol fundamentally changed the time course of impedance and made the otherwise characteristic fast increase of the phase angle of impedance disappear. Already early during ischemia the phase angle was raised in a dose-dependent manner up to even highest values at the beginning of the whole observation period in case of a fully developed effect. Heptanol also stimulated anaerobic energy turnover. The results suggest that, besides unspecific effects, heptanol induces uncoupling which is detectable by electrical impedance measurement.

Alcohols↗

PubMed1990

Glycogen effects on energy state and passive electric properties of liver during protection.

In order to evaluate the importance of glycogen for the hepatic tolerance to ischemia, livers of swine fed a glucose-potassium solution for premedication were perfused with either Bretschneider's HTK-solution (histidine-tryptophan-ketoglutarate) or with Euro-Collins-solution (EC) prior to subsequent ischemia at 25 and 5 degrees C. During ischemia, in regular intervals or continuously, energy rich phosphates, lactate, intrahepatic pH and the electrical impedance of liver tissue were determined. The results were compared with corresponding data from swine which had starved for 48 h. Corresponding to the higher glycogen content, energy supply during ischemia was markedly improved by the premedication. Despite high amounts of glucose in the EC-solution, energy supply after glucose-potassium premedication was no better with EC-solution than with HTK-solution. Moreover, glucose uptake led to concomitant cellular water uptake. Electrical impedance measurements during ischemia mirrored improved energetical protection by the glucose-potassium premedication.

Acid-Base Equilibrium↗