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PubMed1993

Effects of University of Wisconsin solution on endothelium-dependent coronary artery relaxation in the rat.

University of Wisconsin (UW) solution has been reported to enhance myocardial preservation in heart transplantation. To evaluate the effects of UW solution on coronary artery endothelial function, we designed experiments to compare UW solution with a standard crystalloid hyperkalemic cardioplegic solution (CHCS). Isolated rat hearts were studied in a modified Langendorff apparatus for coronary endothelial function. Groups 1 and 2 were perfused with 4 degrees C CHCS (24 mmol/L of KCl) and UW solution, respectively, for 10 minutes at a pressure of 80 cm H2O, whereas group 3 underwent warm ischemia for 10 minutes. Groups 4 and 5 were perfused with and stored for 4 hours in cold (4 degrees C) CHCS and UW solution, respectively. Group 6 underwent 4 hours of topical cooling (4 degrees C) without any cardioplegic perfusion. All groups had 6 hearts each. Endothelium-dependent relaxation and endothelium-independent relaxation of the coronary arteries were tested by infusing 5-hydroxytryptamine (5HT) (10(-6) mol/L) and sodium nitroprusside (10(-5) mol/L), respectively, before and after perfusion with and storage in one of the two cardioplegic solutions. The coronary vasodilatation induced by 5HT and sodium nitroprusside was not altered in hearts perfused with (group 1) or perfused with and stored in CHCS (group 4). Coronary flow increase after 5HT infusion was significantly decreased in hearts perfused with (group 2) (before, 35% +/- 10%; after, 13% +/- 10%; p < 0.01) or perfused with and stored in UW solution (group 5) (before, 34% +/- 5%; after, -5% +/- 12%), indicating severe endothelial dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1983

Comparative results of prolonged hypothermic storage of canine kidneys preserved with hyperosmolar colloid (TP-II) or crystalloid (Euro-Collins) solution.

The function of kidneys stored for 48 to 72 hours in hypertonic crystalloid, intracellular solution, Euro-Collins (360 mOsm./l.), was compared with those stored in a new hyperosmolar (520 mOsm./l.) colloid solution designated as TP-II. The TP-II solution contained less K2HPO4 (1.05 gm./l.) and KH2PO4 (317 gm./l.) and more glucose (40 gm./l.) than the Euro-Collins, and also had an albumin concentration of 4.3 gm./dl. Kidneys obtained from beagle dogs were flushed with either Euro-Collins or TP-II solution (4C). Hypothermic storage followed for either 48 or 72 hours, prior to autotransplantation into the iliac fossa and contralateral nephrectomy. Four experimental groups were transplanted as follows: group 1 (n = 8) and group 2 (n = 7) received kidneys that were flushed with 250 ml. of Euro-Collins or TP-II solution, respectively, prior to 48 hours hypothermic storage. Group 3 (n = 5) and group 4 (n = 5) received kidneys that were flushed in the same way as those in groups 1 and 2, respectively, but were stored for a 72-hour period. TP-II appears to be superior to Euro-Collins for hypothermic storage of kidneys for periods as long as 48 hours. When hypothermic storage times are extended to 72 hours, the number of kidneys with normal function after transplantation is reduced for both solutions, however, TP-II solution has a slight advantage over Euro-Collins solution. Further studies will hopefully clarify this issue and lead to the application of TP-II in the clinical setting.

Animals↗
PubMed2000

Swelling of the collagen-keratocyte matrix of the bovine corneal stroma ex vivo in various solutions and its relationship to tissue thickness.

AIM: The mammalian corneal stroma, like some other connective tissues, can absorb fluid, swell and become oedematous. Since studies on the corneal stroma have been carried out with different types of preparations and solutions, inter-study comparisons are very difficult. A study was thus undertaken on a standardised preparation to assess the relative magnitude of this swelling and its relationship to thickness of the preparations. METHODS: From selected recent post-mortem eyes of adult cattle, stroma preparations were cut from the central part of the cornea. These preparations were immersed in various solutions of known pH and osmolality, and the time-dependent changes in wet mass were assessed over 9 h at 37 degrees C. The relative rates and magnitude of the swelling of the tissue were then compared. RESULTS: A reference value for stromal swelling was obtained by incubation in a 35 mM bicarbonate-buffered mixed salts solution equilibrated with 5% CO2-air (pH 7.60) where a 3.39-fold increase in wet mass and a 4.58-fold increase in thickness was realised in 9 h, at an initial rate of 76 +/- 3%/h. The swelling was essentially the same in an organic buffer-mixed salt solution (pH 7.5) but progressively greater in phosphate-buffered saline (pH 7.5), a range of phosphate buffers (10-67 mM, pH 7.5), NaCl solutions (0.025-1%) and with gross swelling observed in water (where a 15.9-fold increase in wet mass occurred along with a 25-fold increase in thickness, at an initial rate of 643 +/- 62%/h). Overall, the wet mass changes were strongly related to thickness (P < 0.001). CONCLUSIONS: The results confirm that the selection of solution(s) for studies on corneal stromal swelling is critical. The swelling (oedema) is lower in a physiologically-relevant solution (similar to the aqueous humour of the eye). This indicates that the swelling tendency of the corneal stroma has been overestimated in the past, and that a similar discrepancy may also exist for studies on other connective tissues ex vivo when non-physiological experimental solutions are used.

Animals↗
PubMed2000

Effect of irrigating solution and irrigation temperature on the cornea and pupil during phacoemulsification.

PURPOSE: To evaluate the effect of irrigation solution and temperature on pupil diameter, corneal endothelium, and corneal pachymetry during and after phacoemulsification. SETTING: Klinik Dardenne, Bonn, Germany. METHODS: Eighty patients who had cataract surgery by phacoemulsification were assigned to 1 of 4 cross-classified groups and had intraoperative irrigation with room-temperature or refrigerated fortified balanced salt solution (BSS Plus) or modified Ringer's solution. Pupil diameters were recorded at different stages during the surgery. Epithelial cell counts and pachymetry were determined before and 1 day after surgery. RESULTS: The solution temperature did not affect any parameter. The type of solution did not influence endothelial cell loss; however, the solution had a significant effect on corneal pachymetry 1 day postoperatively. The corneas irrigated with BSS Plus were less swollen than the corneas irrigated with Ringer's solution. By day 14, corneal thickness was equal among all groups. CONCLUSION: Long-term results were equally favorable in all 4 groups. However BSS Plus induced less short-term corneal swelling than Ringer's solution. From these findings, it appears that BSS Plus may decrease corneal risk in cases with compromised corneas or prolonged surgery.

Adult↗
PubMed2003

Scanning electron microscopic study of cold-stored small bowel: comparison of Euro-Collins and Lactated Ringer's solutions.

The increasing use of the small bowel for transplantation necessitates the development of optimum preservation techniques. The aim of our study was to investigate time-related morphological changes of the rat small bowel during preservation of the organ in hypothermic Euro-Collins and Lactated Ringer's solutions. It is the only study comparing these widely used preservation solutions with scanning electron microscopy, which is especially suitable to show the intestinal mucosa, one of the tissues of the intestine most susceptible to ischemia. Small bowels were perfused with either Euro-Collins, Lactated Ringer's or physiological saline solution and placed in respective preservation solutions at 4 degrees C for 0, 3, 6 and 12 hours. Biopsy samples were prepared for examination at the light and scanning electron microscopic levels. According to the results of this study we conclude that, even Lactated Ringer's solution showed better tissue preservation than Euro-Collins solution, both preservation solutions are suitable for short term preservation of the small bowel and that further ameliorations of the preservation solutions and/or techniques are required for long term preservation.

Animals↗
PubMedDate not supplied

The use of frozen intravenous crystalloid solutions as the refrigerant for shipping blood.

The authors studied whether cooled sterile intravenous crystalloid solutions could be used to refrigerate red cells during shipment. Six 1000-ml bags of 0.9 percent normal saline and lactated Ringers (RL) solutions were supercooled and tested separately at temperatures ranging from 1 to -78 degrees C, with either 5 or 30 units of packed red cells (PRBCs). The PRBCs were shipped in a standard military container that permitted separation of the supercooled solutions from the PRBCs. Cooling RL solutions to 6 degrees C and to -22 degrees C maintained acceptable storage temperatures of the PRBC for 36 and 50 hours, respectively, and did not cause visible damage to the units. No significant changes were observed in various biochemical measurements of the cells and plasma. Cooling the RL solution to -78 degrees C caused a significant (p less than 0.05) increase in plasma potassium concentration. The effectiveness of the crystalloid solutions in refrigerating blood varied with the ratio of the number of PRBCs to the volume of cooled solutions and with the ambient temperature surrounding the container. The results of this study suggest that cooled intravenous crystalloid solutions can be used as refrigerants for PRBCs during shipment.

Blood Preservation↗
PubMed1998

Intestinal water absorption--implications for the formulation of rehydration solutions.

Absorption of ingested water and most solutes occurs in the proximal small intestine, therefore the rate at which beverages are emptied from the stomach is an important factor in determining the rate of water absorption. In the small intestine, water absorption is brought about by the creation of suitable osmotic gradients that promote net uptake of water from the intestinal lumen. The absorption of solute, especially that brought about by active carriers, are highly effective in creating the osmotic gradients that promote net water uptake. The activation of these transporters also increases the permeability of the mucosa which helps absorption. Moderate hypotonicity of the luminal contents potentiates solute-induced water absorption while hypertonicity slows fluid absorption. Dilute hypotonic glucose-sodium solutions are highly effective oral rehydration solutions, and the type of carbohydrate used does not appear to be important. The addition of other actively absorbed solutes gives little benefit in potentiating water uptake. The inclusion of sodium in rehydration solutions may not be required to stimulate water absorption but probably assists the overall rehydration process. The amount of glucose required to stimulate water absorption is relatively small and for rehydration purposes ingestion of an adequate amount of a dilute solution is more beneficial than drinking a smaller volume of a more concentrated beverage.

Biological Transport↗
PubMed1987

Effects of tonicities of saline solutions on pulmonary injury in drowning.

We studied the degree of pulmonary and hemodynamic compromise induced by six saline solutions of varying tonicities (0%, 0.225%, 0.45%, 0.9%, 2%, and 3%) instilled down the trachea. We also attempted to resuscitate the dogs after a simulated wet drowning in each of the solutions, with and without chlorine. A control study with similar degree of anoxia but no fluid in the lungs was also performed. For the pulmonary variables of alveolar-arterial oxygen pressure difference, intrapulmonary shunt fraction, and PaO2/fraction of inspired oxygen, the 0.225% NaCl solution was significantly (p less than .001) less injurious to the lungs, especially compared with sterile water. The 0.225% and 0.45% NaCl solutions were the least disruptive to pulmonary function; the pulmonary injury they produced was similar to injury in the control dogs. Chlorine in the solution at one to two parts per million did not influence the data. The 0.9% (isotonic, normal saline), 2%, and 3% NaCl drowning solutions showed little difference from one another in terms of pulmonary injury. They were significantly (p less than .05) better than sterile water and significantly (p less than .05) worse than the 0.225% and 0.45% NaCl solutions. Sterile water, whether chlorinated or not, was the most injurious to the lungs. The hemodynamic effects of the drowning solutions were explainable solely by the effects of anoxia.

Animals↗
PubMed1990

Examination of the role of the impermeants lactobionate and raffinose in a modified UW solution.

Rat liver transplants were performed in order to assess the importance of the impermeant anion lactobionate and the trisaccharide raffinose on the effectiveness of a simplified variant of UW solution for liver preservation by simple cold storage. Rat livers were stored at 4 degrees C for 18, 24, 30, or 40 hr in a modified UW solution or in one of three variants of UW in which one of these impermeants was replaced by another more permeable agent. Using modified UW solution (solution A), 50% (5/10) of rats receiving livers that had been preserved for 30 hr survived for more than 1 week; with solution B, which differs from A in the replacement of raffinose by glucose, the 1-week survival was 60% (6/10) after 30-hr preservation. Solution C, which is identical to A except for the replacement of lactobionate by gluconate, gave 20% (2/10) survival rate after 30-hr preservation. However, using solution D, which is identical to A except for substitution of chloride for lactobionate, none (0/8) of the rats receiving liver preserved for 30 hr survived. These results suggest that the inclusion of lactobionate as a major anion plays a crucial role in the effectiveness of UW solution, whereas raffinose can be replaced by more permeant glucose without deleterious effect.

Adenosine↗
PubMed1993

The role of preservation solutions in coronary endothelial damage during cold storage.

The effects of cold storage and type of preservation solution on coronary endothelial function are not well understood. Experiments were designed to evaluate coronary endothelial-dependent relaxation after a 4-hr cold (4 degrees C) storage in different preservation solutions. Isolated rat hearts were studied in the Langendorff apparatus for coronary endothelial function. After 30 min of stabilization, hearts were arrested with a 10-min perfusion of 4 degrees C crystalloid hyperkalemic cardioplegic solution (CHCS) containing 24 mmol/L of KCl and stored for 4 hr in the following preservation solutions: CHCS, Krebs-Ringer's solution (KR), 0.9% NaCl (NS), and University of Wisconsin solution (UW). A fifth group was perfused and stored in UW solution. Endothelial-dependent and independent coronary artery vasorelaxation were tested, respectively, by infusing 5-hydroxytryptamine (5-HT) (1 x 10(-6) mol/L) and sodium nitroprusside (SNP) (1 x 10(-5) mol/L) before and 30 min after the storage period. In hearts stored in CHCS and KR, the coronary artery flow increase to 5-HT and SNP infusion were not significantly affected. However, in hearts preserved with NS and UW solutions, 5-HT coronary response was significantly decreased, indicating endothelial dysfunction. In addition to these findings, coronary flow increase to SNP infusion was decreased in the group perfused and stored with UW, suggesting smooth muscle damage. These experiments suggest that 4-hr cold storage in NS or UW impairs endothelial-dependent coronary relaxation in the isolated rat heart model.

Adenosine↗
PubMed1992

Small bowel tissue high-energy phosphate alterations during hypothermic storage using different protecting solutions.

Since posttransplant function is closely related to energy status after the storage period, the aim of our study was to determine high-energy phosphates in rat small bowels after 21 h of simple ischemic cold storage using different storage solutions. We compared Eurocollins-solution, Bretschneiders-HTK-solution and a modified University of Wisconsin-solution. After flushing the small bowel both intravascularly and intraluminally with the protecting solution, segments of rat small bowel were stored in the same solution at 4 degrees C for 21 h. Determination of high-energy phosphates by high-performance liquid chromatography were done at indicated times. We found that small bowel stored in Eurocollins-solution produced the best graft viability after 21 h of cold storage by maintaining a sufficient level of high-energy phosphates. The high ATP levels were produced by the pronounced anaerobic glycolysis which was facilitated by the high concentration of glucose in the Eurocollins-solution.

Adenosine↗
PubMedDate not supplied

The use of different time/temperature combinations in the optimization of sterilization of Ringers/glucose infusion solution.

The effect of sterilization temperature and sterilization efficacy (F0) on the amount of 5-hydroxymethyl-2-furaldehyde (5-HMF) and glucose, number of particles generated and color of Ringers/glucose infusion solution is described. The infusion solution was a 5% glucose solution containing Ringer-type electrolytes. The solutions were autoclaved in a pilot scale autoclave using different temperature/time combinations to produce the target F0 values of 10, 15, 20 and 25 minutes. The amounts of 5-HMF and glucose were determined by HPLC. The use of the shortest possible sterilization cycle to yield the target F0 resulted in the lowest 5-HMF concentrations in the Ringers/glucose infusion solutions studied. The spectrochromatograms of the sterilized solutions showed that glucose is degraded into various degradation products in the presence of Ringer-type electrolytes. It was also demonstrated by SEM/EDX that a significant part of the particles result from the leaching of the silicon oil used in the manufacture of rubber stoppers for LVP solutions. The number of particles generated in different solutions and the particle size distributions were determined with a Coulter-Counter. The particle size distributions show no clear correlation between sterilization process conditions and the number of particles. The results show that it is possible to minimize the amount of 5-HMF generated even when the same F0 is used, by choosing the highest sterilization temperature possible. This also leads in practice to the shorter sterilization processes, saving both process time and energy.

Furaldehyde↗
PubMed1992

Superior qualities of University of Wisconsin solution for ex vivo preservation of the pig heart.

The components of the University of Wisconsin solution have the potential to enhance and extend heart preservation. We have evaluated University of Wisconsin solution by comparing it with St. Thomas' Hospital cardioplegic solution in the isolated pig heart subjected to 8 hours of ischemia at 4 degrees C (n = 6 in each). The hearts were perfused ex vivo with enriched autologous blood for the control and the postpreservation assessments. Morphologic, metabolic, and functional evaluations were performed. Left and right ventricular function as assessed by the slope values of systolic and diastolic pressure-volume relationships of isovolumically contracting isolated heart was better preserved by University of Wisconsin solution (percent reduction: left ventricular systolic, 52.4% +/- 5.5% versus 17.7% +/- 6.7% [p less than 0.001]; right ventricular systolic, 125.6% +/- 46.4% versus 65.5% +/- 31.4% [p less than 0.05]; right ventricular diastolic, 112.3% +/- 48.7% versus 40.2% +/- 31.3% [p less than 0.02] after St. Thomas' Hospital and University of Wisconsin preservation, respectively). Postischemic recovery of left ventricular rate of rise of pressure and myocardial oxygen consumption were significantly improved after University of Wisconsin preservation (percent reduction, rate of rise of pressure: St. Thomas' Hospital 39.3% +/- 8.1%; University of Wisconsin 18.1% +/- 4.6%; percent reduction, myocardial oxygen consumption St. Thomas' Hospital 55.1% +/- 6.9%, University of Wisconsin 24.8% +/- 6.7%; p less than 0.001). Microvascular functional integrity as assessed by coronary vascular resistance was well maintained throughout the postischemic period and was similar to the preischemic control value in the University of Wisconsin group. By contrast, a significant increase was found at the beginning of postpreservation reperfusion, with a progressive rise thereafter in the St. Thomas' Hospital group (p less than 0.001). Preservation of myocardial adenosine triphosphate was improved and energy charge was unchanged after 8 hours of ischemia and reperfusion in the University of Wisconsin-preserved hearts compared with the St. Thomas' Hospital-preserved hearts (p less than 0.01). Electron microscopic examination revealed substantially better preservation of the contractile apparatus after preservation with University of Wisconsin solution. Myocytes from hearts receiving University of Wisconsin solution, unlike those given St. Thomas' Hospital solution, showed relaxed myofibrils with prominent I-bands. We conclude that University of Wisconsin solution has the potential to improve the preservation of the heart and possibly prolong the ischemic period in clinical cardiac transplantation.

Adenosine↗
PubMed1992

Cardiac preservation by continuous perfusion of the University of Wisconsin solution.

Recent studies have shown that the University of Wisconsin (UW) solution may be superior to standard solutions in preserving the isolated heart before transplantation. The authors compared the UW solution with a modified Krebs-Henseleit solution in a continuous hypothermic coronary perfusion model. Hearts from mongrel dogs were rapidly excised after hyperkalemic arrest with standard cardioplegia and were mounted in a perfusion apparatus for 24 hours. Twelve hearts were perfused with the Belzer UW solution (group 1), and 15 hearts were perfused with a modified Krebs-Henseleit solution (group 2). The hearts were transplanted in a cross-circulation model, and parameters of function (developed pressure [dP] and rate of pressure development [+/- dP/dt]) were measured. Mean (+/- SEM) developed pressure was 80 +/- 7 mm Hg in group 1 and 56 +/- 9 mm Hg in group 2 (p less than 0.05). The +dP/dt was 1433 +/- 126 mm Hg/s in group 1 and 843 +/- 154 mm Hg/s in group 2 (p less than 0.005), and the -dP/dt was 958 +/- 110 mm Hg/s in group 1 and 676 +/- 106 mm Hg/s in group 2 (p less than 0.05). The UW-preserved hearts also required fewer defibrillations (0.75 +/- 0.13) to establish a stable rhythm than the control hearts (5.87 +/- 2.07, p less than or equal to 0.02). There were no significant differences in weight gain, coronary resistance or creatine phosphokinase levels between the two groups. The authors conclude that the UW solution provides better preservation of function than a modified Krebs-Henseleit solution for continuous coronary perfusion.

Adenosine↗
PubMed1991

Morphology of sickle cells produced in solutions of varying osmolarities.

The effect of varying osmolarities (0.6% to 1.5% NaCl solutions, 213 to 492 mOsm/kg H2O) on the morphology of deoxygenated sickle cells was studied quantitatively with a computer-assisted image analysis system. Discocyte-rich, less dense fractions of sickle cells (density less than or equal to 1.11) were suspended in buffered NaCl solutions (pH 7.4) of various osmolarities, deoxygenated at room temperature for up to 5 hours, and stained by Wright's solution. Microscopic images were analyzed by circular shape factor (CSF = 4 pi x [area]/[perimeter]2) and elliptical shape factor (ESF = [short axis]/[long axis]). Since these two parameters yield different values for elongated cells and for cells of other shapes, such as maple-leaf- or star-shaped cells, the morphologic changes of sickle cells can be analyzed numerically. We found that both the rate and the degree of deformation depended highly on the osmotic pressure of the media in which the cells were suspended. In hypertonic solution, most sickle cells assumed a maple-leaf shape. The deformation occurred quickly, but the degree of deformation (circular shape factor and elliptical shape factor) was lower than that found in isotonic and slightly hypotonic solutions. Although elongated cells were formed in hypotonic and isotonic solutions, deformation was slower in these solutions than in hypertonic solutions. These results indicate that the shape and the degree of deformation of deoxygenated sickle cells are highly dependent on the osmolarity of the suspending medium and that the rate of deformation is inversely related to osmolarity. The relationship between morphology of deoxygenated sickle cells and osmotic pressure of the suspending media is discussed.

Buffers↗
PubMed1994

Monoclonal antibody delivery to intraperitoneal tumors in rats: effects of route of administration and intraperitoneal solution osmolality.

Monoclonal antibody (MAb) transport in peritoneal tissue is dominated by convection, which is dependent on the net driving force of i.p. hydrostatic and osmotic pressure. To test the hypothesis that the i.p. osmolality has significant effects on IgG delivery to the tumor during the acute period after injection, solid tumors (FEMX-II) were transplanted into the anterior abdominal wall of nude rats. The wall is subject to well-defined pressure forces from the solution in the cavity. MAb 96.5, which specifically binds to FEMX-II cells, was simultaneously injected i.v. (111In-MAb 96.5 in Krebs Ringer solution) and i.p. (125I-MAb 96.5 in dialysis solution). Intraperitoneal hydrostatic pressure was held constant, and the osmolality of the i.p. solution was varied between isotonic and hypertonic (with the addition of 4% mannitol to an isotonic salt solution) in order to vary the direction of net convection. Plasma and peritoneal concentrations of both isotopes were measured at intervals over 200 min, and tissue concentration profiles in tumor and adjacent normal tissue were determined by dual-label quantitative autoradiography at 200 min. After i.v. administration, profiles were relatively flat and little affected by i.p. osmolality. After i.p. injection, profiles demonstrated steep concentration decreases from the peritoneal surface into the tissue for several hundred microns. Despite the change from the condition of water absorption from the cavity into the body (isotonic solution) to one of net volume gain by the cavity (hypertonic solution), tumor profiles were affected by i.p. osmolality only near the surface. Specific binding properties of the tumor were determined for the tumors studied and were consistent with high surface concentrations relative to normal tissue. Variation of the i.p. solution osmolality by changes in concentration of small molecules exerts only minor effects on the short-term MAb delivery from either systemic or regional administration to a target tumor in the anterior abdominal wall in the rat.

Abdominal Muscles↗
PubMed1993

[Effect of different solutions of preservatives on the endothelial function of coronary arteries in rats].

The effects of cold storage and type of preservation solution on coronary endothelial function are not well established. Experiments were designed to evaluate coronary endothelial-dependent relaxation after a 4-hour cold (4 degrees C) storage in different preservation solutions. Rat hearts, mounted in the Langendorff apparatus, were arrested with a 10-minute perfusion of 4 degrees C crystalloid hyperkaliemic cardioplegic solution (CHCS) (KCl 24 mEq/l) and stored for 4 hours in the following preservation solutions: CHCS (n = 6), Krebs-Ringer solution (KR) (n = 6), 0.9% NaCl (NS) (n = 6) and the University of Wisconsin solution (UW) (n = 6). A fifth group (n = 6) was perfused and stored in UW solution. Endothelium-dependent and independent coronary artery vasorelaxations were respectively tested by infusing 5-hydroxytryptamine (5-HT) (10(-6) mol/l) and sodium nitroprusside (SNP) (10(-5) mol/l) before and after the storage period. In hearts stored with CHCS or KR, coronary artery flow increase to 5-HT and SNP infusions were not significantly affected. However, in hearts preserved with NS or UW solutions, 5-HT coronary response was significantly decreased, indicating endothelial dysfunction. In addition to these findings, coronary flow increase to SNP infusion was decreased in the group perfused and stored with UW, suggesting smooth muscle dysfunction. These experiments suggest that 4-hour cold storage in NS or UW impairs endothelial-dependent coronary relaxation in the isolated rat heart model.

Adenosine↗
PubMedDate not supplied

Solubility of lead as lead (II) chloride in HEPES-Ringer and artificial seawater (Ca-ASW) solutions.

Total dissolved Pb was measured in a number of commonly used physiological solutions by electrothermal atomization atomic absorption spectrometry (ETA-AAS). In HEPES-buffered solutions (pH 7.30) the concentration of total Pb in solution ("measured" Pb) was only 77% of nominal Pb up to 20 microM added Pb, where experiments were undertaken at room temperature (22 +/- 1 degree C). However, test solutions equilibrated at 37 +/- 1 degree C contained 99% of added Pb up to 2 microM. Above this nominal concentration, percentage recoveries dropped to approximately 72% at a nominal concentration of 20 microM. Tris-buffered artificial seawater (CaASW) solutions (pH 7.60) contained more dissolved Pb compared to HEPES-buffered solutions at 22 degrees C. However, increasing the calcium concentration in ASW appeared to increase precipitation of PbCl2. Concentration-corrected dose-response relationships were plotted from previously published data on the effects of Pb on voltage-activated calcium channels of rat dorsal root ganglion (DRG) cells and Aplysia neurons. The plots suggest that the inhibitory effects of Pb on rat DRG cells may prevail at concentrations of Pb even lower than reported previously when measurements were made at 22 degrees C. However, increasing the temperature to 37 degrees C resulted in closer agreement between measured and nominal dose-response curves. The measured dose-response curves for the Tris-buffered ASW solutions closely followed those of the nominal up to 200 microM Pb. In ASW solutions containing 40 mM calcium, PbCl2 was precipitated at Pb concentrations greater than 200 microM.

Animals↗