Effects of preservation conditions and temperature on tissue acidification in canine kidneys.

The influence of temperature (5, 15, 25, and 35 degrees C) on the degree of tissue acidification was examined using 74 canine kidneys with simple ischemia or after protection of the kidneys with Euro-Collins solution or with the HTK-solution of Bretschneider. At an incubation temperature of 5 degrees C, the intrarenal pH value in HTK-protected kidneys is continuously higher than 7.3 during 36 hr of ischemia. In Euro-Collins kidneys the pH value decreases to a pH of 6.4 during this time. In simple ischemic kidneys pH is 6.3 after 36 hr. At 15 degrees C the pH value falls to a lower level in Euro-Collins kidneys than in purely ischemic kidneys, but the pH in HTK-protected kidneys is higher than 6.9 for 24 hr. At 25 degrees C, and especially at 35 degrees C the intrarenal acidosis in Euro-Collins kidneys is much stronger than in unprotected kidneys, and the pH in HTK-protected kidneys does not decrease below 6.7. The lactate production in simple ischemic kidneys and in HTK-protected kidneys is nearly the same (80-100 mumol/gdw), although Euro-Collins kidneys have a steeper increase and reach higher lactate levels (330 mumol/gdw). The HTK solution guarantees satisfactory protection against damaging acidosis over the whole temperature range (5-35 degrees C), but the Euro-Collins solution leads to a stronger and more dangerous acidosis the higher the temperature.

Glucose content and efficiency of glycolysis in protected ischemic kidneys of different species.

In ischemic canine kidneys protected by Bretschneider's HTK solution the glycolytic lactate production is limited by a low renal substrate content. However, for anaerobic energy supply ischemic organs depend on glycolysis. To evaluate the role of glycolysis in renal protection, the relationship between lactate production and anaerobic energy supply was examined in protected kidneys of dogs, sheep, and swine. Additionally, in canine kidneys an attempt was made to improve anaerobic energy provision by adding glucose to the protective solution. The results were as follows: (1) According to increasing lactate production from swine to dog to sheep, intraischemic ATP decay was delayed least in swine and most in sheep. (2) Glucose addition (10 mM) to the HTK solution roughly doubled the time for ATP to fall to 1 mumol/g dry wt (tATP) in dogs. (3) The greater the lactate production in all three species, the lower the decrease in SAN (ATP + ADP + AMP) from 5 to 120 min of ischemia. (4) A glucose additive in the protective solution led to a significant (p less than .005) increase of SAN in dogs at 120 min of ischemia. A sufficient substrate supply seems to be an essential component of a reliable renal protection.

[Clinical use of the Bretschneider HTK cardioplegic solution for in situ protection of the kidney]. / Klinische Anwendung der kardioplegischen Lösung HTK nach Bretschneider zur in-situ-Protektion der Niere.

The first clinical use of Bretschneider's HTK-solution for in-situ-protection of the kidney in mild hypothermia is reported. By means of this protective method renal surgery can be performed in a bloodless field without permanent loss of renal function. After initial protective perfusion of the kidney no repeated perfusions or additional surface cooling must be done. There are no systemic side effects when the HTK-solution is applied appropriately.

[Kidney function parameters following ischemia stress using the Euro-Collins solution or the Bretschneider cardioplegic HTK solution]. / Nierenfunktionsparameter nach Ischämiebelastung unter der Euro-Collins-Lösung oder unter der kardioplegischen Lösung HTK nach Bretschneider.

Protection-methods, for an improvement of ischemic tolerance of the kidney, can be investigated by intraischemic analysis of metabolism and structure. A definite proof for the effectiveness of a protection method is only postischemic function in combination with postischemic structure-regeneration. For this reason postischemic function was chosen for examination of the protective ability of the Euro-Collins-solution and the HTK-solution during a two-hour reperfusion period. We perfused 57 dog kidneys either with the Euro-Collins- or with the HTK-solution prior to ischemia. Ischemia was 7, 60, 90 and 120 min after Euro-Collins-perfusion and 7, 120, 150 and 180 min after HTK-protection. The protected and ischemic kidneys were left in-situ; the mean ischemic temperature was therefore 20-25 degrees C for the shorter ischemic times and 30-34 degrees C for the longer ischemic times. We compared the protected and ischemic kidneys with 14 untreated kidneys (control). Postischemic renal blood flow (RBF) was measured by an electromagnetic flow probe; renal oxygen consumption (V02/min) was calculated by arterio-venous oxygen content difference and the renal blood flow. If urine could be collected, the glomerular filtration rate (GFR) was measured by an endogenous creatinine clearance. In Euro-Collins-protected kidneys after 60-120 min ischemia the RBF was after 15 min of reperfusion between 20 and 100 ml/min/100 g. After 30 min we got values of 100-200 ml/min/100 g. The V02/min, which was in the control kidneys between 5-6 ml/min/100 g, was about 2 ml/min/100 g.(ABSTRACT TRUNCATED AT 250 WORDS)

[Measuring electric impedance of organs--methodologic principles]. / Messung der elektrischen Impedanz von Organen--Methodische Grundlagen.

Ischemia causes changes in organ tissue (e.g. during operation or transplantation) which may finally lead to irreversible injury, so that the organ can no longer be resuscitated. To the extent that these changes affect the electrical properties of the tissue they are manifested in the impedance spectrum. As an example, the course of impedance of a HTK-protected porcine liver is presented in the frequency range of 0.1 Hz to 10 MHz, which includes two dispersion--alpha- and beta-dispersion. Using a suitable electrical equivalent circuit analogue to the structure of the liver, the behavior of the alpha- and beta-dispersion is explained on the basis of gap junction closure and narrowing of the extracellular space due to cell swelling.

Postischemic diagnostic localization of tubular lesions.

Several functional parameters were applied in an experimental model of ischemia to test the ability to localize the distribution of tubular lesions. Canine kidneys were perfused with protective solutions and rendered ischemic for definite periods. Renal function was determined during a subsequent 3-h reperfusion. The pattern and the extent of renal injury were influenced by varying the duration of ischemia and by modifying the protective solution used. The results suggest that by employing an appropriate selection of parameters it is possible to allocate renal injury to definite sections of the tubules. According to such an evaluation, under protection with HTK-solution, the proximal tubule limits the tolerance of renal ischemia. The thick ascending limb shows some vulnerability that is aggravated by disadvantageous modifications of the protective solution and that may become more pronounced in the course of reperfusion. In contrast, more distal parts of the nephron retain a remarkable reserve transport capacity after a tolerable level of ischemia.

Urinary LDH-release for evaluation of postischemic renal function.

Following renal ischemia under protection, the perfusion of the tubular system increases concomitant to the rise of GFR. The transport into urine of enzymes entering the tubular lumen due to ischemic injury is dependent on tubular flow. Thus, we examined if in the early postischemic phase urinary enzyme determinations can contribute to the evaluation of the ischemic injury despite the interference of a changing tubular washout. Canine kidneys were perfused with different protective solutions and subsequently rendered ischemic. From the beginning of reperfusion the endogenous creatinine clearance, the urine minute volume and the urinary LDH-concentration were determined. The urinary LDH-concentration allowed only a rough assessment of renal ischemic damage. The adjustment of the urinary LDH amounts to the GFR resulted in a better graduation according to the ischemic stress. With such a standardized LDH parameter the urinary LDH release was somewhat lower on the average when L-aspartate was added to the HTK solution in place of chloride. In conclusion, during the early postischemic recovery after renal protection the examination of the urinary enzyme release may be a useful diagnostic means for the assessment of the extent of the ischemic injury if an appropriate frame of reference is applied.

Contribution of amino acids in protective solutions to postischemic functional recovery of canine kidneys.

Amino acids are known to increase glomerular filtration rate (GFR). There is also an early resumption of filtration following 2-h renal ischemic stress under protection by histidine-buffered histidine-tryptophan-ketoglutarate solution (HTK), possibly due in part to an amino acid effect. Hence, we have examined the possibility of further enhancing the postischemic GFR by adding 32 (ASP I; 4 mM Mg2+) or 36 (ASP II; 6 mM Mg2+) mM L-aspartate (asp) or 32 mM DL-aspartate (ASP III) to the HTK solution in place of chloride. After infusion of 500 ml 5% glucose, canine kidneys were protected by an 8-min perfusion with HTK (n = 5), ASP I (n = 4), ASP II (n = 5) or ASP III-solution (n = 3). The subsequent ischemia lasted for 2 h at 27-31 degrees C. During reperfusion, both GFR and filtration fraction (FF) were higher in kidneys protected by L-aspartate-containing solutions. ASP III showed no improvement against HTK. An additional preischemic intra-aortal application of HTK or ASP I solution just above the exit of the renal arteries prior to the intrinsic protective perfusion further raised the postischemic GFR. The present results suggest that L-aspartate but also histidine may have favorable amino acid effects in renal protective solutions in addition to known positive effects of histidine.

Intraischemic metabolic effects of different disaccharides on protected canine kidneys.

The addition of the disaccharides maltose (10, 20, 30 mM) and sucrose (30, 60 mM) to Bretschneider's organ protective HTK solution was evaluated to improve renal protection by an enhanced glycolytic energy supply. Canine kidneys were perfused for 8 min with either HTK solution or HTK solution containing additional disaccharides. After nephrectomy the kidneys were incubated at 25 degrees C and metabolic parameters were determined at regular intervals. Maltose and sucrose are slowly cleaved during renal ischemia but maltose distinctly faster than sucrose. Maltose increases intraischemic ATP supply. However, 30 mM maltose was no better than 10 mM. 60 mM sucrose was about as effective for glycolysis as 10 mM maltose. However, possibly due to fructose release there was an accelerated decrease of adenine nucleotides with sucrose. Although fructose enters glycolysis it seems to have negative side-effects. Hence, probably neither sucrose nor fructose are appropriate for renal substrate supply during ischemia.

Postischaemic interrelations between energy metabolism and functional recovery of protected canine kidneys.

Following renal ischaemia under effective protection glomerular filtration starts at a time when renal high-energy phosphates are resynthesized. The present investigation was carried out to examine the interdependence of the two processes. Therefore, canine kidneys were protected with sodium poor and nominally Ca2+ free buffered solutions. After different times of ischaemia and reperfusion the glomerular filtration rates (GFR) were determined and afterwards tissue specimens were excised for the determination of high-energy phosphates. Both the GFR and the renal energy content were higher with shorter ischaemia periods or longer reperfusion. As a rule there was a correlation between GFR and ATP, both probably mainly signifying the degree of preservation of proximal nephron sites, as the interrelation between the GFR and the renal SAN (ATP + ADP + AMP) content also signifies. However, with the addition of aspartate to the protective solution it could be demonstrated that the GFR also can rise without a concomitant increase of ATP. Under certain conditions an increase of GFR can even be associated with a lowering of the renal ATP content.

["Imperative indication" for organ-preserving kidney tumor surgery]. / "Imperative Indikation" zur organerhaltenden Nierentumorchirurgie.

Imperative indications for organ-sparing surgery of renal tumors are given mainly in existing or imminent restriction of renal function. Organ-sparing excision of renal tumors under in-situ protection with HTK-solution compared with operations without protection have the following advantages: 1. reduced blood loss, 2. longer ischemia, 3. better tissue differentiation with benefit for radicality, 4. shorter hospital stay.

Unusual negative side effects of non-steroidal anti-inflammatory drugs in the proximal colon.

Two cases of uncommon side effects of non-steroidal anti-inflammatory drugs (NSAID) are presented which show that in special cases NSAID lesions can be located predominantly in the proximal colon, that NSAID-caused lesions may present themselves as diaphragm-like strictures and that alterations by NSAID in this part of the bowel may bring enormous problems for the differential diagnosis.

Influence of glycogen content, temperature, and Euro Collins solution on membrane potential and sodium activity of superfused porcine liver slices.

The influence of glycogen content, temperature, and Euro Collins (EC) solution on membrane potential (Vm) and intracellular sodium activity (aNai) were measured in cells of superfused porcine liver slices by means of double-barrelled ion-sensitive microelectrodes. Vm was -26.1mV in fasted pigs and -20.6mV after glucose feeding, when measured in HEPES-buffered solution (P less than 0.0001). aNai was not measurably affected by glucose feeding. During superfusion with Tyrode solution, lowering the temperature from 35.5 degrees C to 15.5 degrees C led to a fast Vm decrease of roughly 2mV followed by an increase of 1-3mV. At the same time, aNai increased from 12.8 to 18.2mM within 10 min. Superfusion with EC solution for 10 min caused comparable changes in fed and fasted pigs. Vm depolarized at either temperature by about 16mV. At 35.5 degrees C the initial aNai of 17.5mM was roughly halved, whereas at 15.5 degrees C it decreased from 21.0 to 14.3mM. The results suggest that the nutritional state markedly affects the electric properties of liver. However, the effect on membrane potential of high-potassium organ-protective solutions seems to be distinctly more pronounced. Moreover, cellular Na+ activity decreases in consequence of an extracellular Na+ reduction with protective solutions, which might be balanced to some extent by a simultaneous temperature decrease.

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.

The role of prostaglandines in peristalsis of the human colon.

Prostaglandines (PG) of the E and F series cause peristaltic activity in isolated longitudinal muscle strips of the human colon. As this phasic motor reaction can be varied by acetyl choline and adrenaline it was supposed, that prostaglandines contribute to peristalsis. The role of PG E and F in the human colon was studied by inhibiting the prostaglandine synthesis and by antagonizing the prostaglandine-effects. Indomethacin proved to be a suitable inhibitor. HR 546 was found a powerful antagonist. The effect of Pentagastrin and Cholecystokinin (CCK) on peristaltic activity were suppressed by Indomethacin and HR 546. The inhibition of peristalsis by Indomethacin and HR 546 was removed by high doses of PG E and F. On the basis of these results the role of PG for the motility of the gut is discussed.

Construction and experimental application of a catheter for selective arterial kidney perfusion in situ.

In order to improve dog kidney perfusion in situ with a protective solution, a perfusion catheter was constructed which allowed continuous pressure measurement in the center of the catheter tip during perfusion. Using this catheter, the equilibration of the extracellular space with a protective solution (HTK solution) was found to be pressure dependent. Continuous pressure and resistance control is therefore a prerequisite for reliable organ protection.

Post-ischemic renal function after kidney protection with the HTK-solution of Bretschneider.

The cardioplegic solution HTK of Bretschneider was used for canine kidney protection. The kidneys were perfused with this solution for 6-10 min prior to the induction of ischemia. The kidneys were left in-situ for 60, 90, 120 and 135 min ischemia time at a temperature of 25-34 degrees C (n = 13). As a control group we used unilateral nephrectomized dogs (n = 9). After unilateral nephrectomy an elevated plasma creatinine in comparison to preoperative values was observed. After 60 and 90 min under HTK-protection the postoperative plasma creatinine was not elevated compared to the control group. After 120 min of ischemia creatinine level was slightly increased to an average of 2.1 mg% on the first and second postoperative day. These experiments indicate the protective effect of the cardioplegic solution for canine kidney preservation in situ.

Short-term perfusion and "equilibration" of canine kidneys with protective solutions.

Kidneys were perfused either with Euro-Collins-solution or with HTK-solution of Bretschneider. The perfusion pressure as well as the perfusion flow were measured during a six-minute perfusion. The perfusion resistance was higher in Euro-Collins-kidneys than during HTK-perfusion. The venous outflow of the kidney as well as the ureteral outflow was measured during each minute of the perfusion and has analysed for osmolality, and for sodium and potassium concentrations. In Euro-Collins-kidneys a complete "equilibration" of the extracellular space was not achieved, while during HTK-perfusion concentrations in the venous as in the tubular outflow, similar to those in the HTK-solution itself, could be reached. At the end of the different perfusions, tissue was analysed for biochemical parameters such as ATP, ADP, AMP and lactate as well as for morphological features. Lactate had increased and ATP had decreased during perfusion with Euro-Collins-solution, while ATP had not changed and lactate had decreased during perfusion with HTK-solution. Normal glomerular, tubular and dilated vascular structures can be seen after HTK-perfusion, while a glomerular and vascular contraction takes place during Euro-Collins-perfusion.