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At least 379 records · Page 21Linked to original sources
PubMed1996

Effect of length and contraction on coronary perfusion in isolated perfused papillary muscle of rat heart.

We studied the impeding effect of cardiac muscle contraction on coronary arterial inflow in six isolated, perfused papillary muscles of the rat. Special attention was given to the effect of changes in muscle length and contractility on flow impediment in systole. Contractility was changed by resumption of pacing after a quiescent period of 60-100 s or by doubling the calcium concentration in the perfusate and the superfusion fluid from 1 to 2 mM. The vascular bed was maximally dilated with adenosine, and perfusion pressure was kept constant at 69 +/- 3 cmH2O. We found that contractions impede arterial inflow by 29% [from 17.3 +/- 2.2 ml.min-1.g-1 during diastole to 12.4 +/- 1.8 (SE) ml.min-1.g-1 at peak systole, P < 0.001] while the muscle was kept at 90% of maximum muscle length (MLmax). When the muscle was stretched from 80 to 97% of MLmax, diastolic force increased from 0.5 +/- 0.3 to 11.1 +/- 1.2 mN/mm2, systolic force increased from 11.1 +/- 1.5 to 44.6 +/- 4.0 mN/mm2, diastolic flow decreased by 12% (from 18.2 +/- 2.3 to 15.9 +/- 1.9 ml.min-1.g-1, P < 0.05), and systolic flow decreased by 3% (12.4 +/- 2.3 to 12.0 +/- 1.6 ml.min-1.g-1, P = NS). Increased contractility by elevated [Ca2+] did not affect diastolic flow but increased systolic flow impediment from 29 to 39% (systolic flow decreased from 12.4 +/- 1.8 to 10.3 +/- 1.4 ml.min-1.g-1, P < 0.01). The results are qualitatively similar to findings in the intact heart. Limitations on quantitative comparison due to differences in muscle architecture and differences in force vectors in the papillary muscle and the left ventricle are discussed. The results show that ventricular pressure is not essential in systolic coronary arterial flow impediment. The findings are in agreement with the varying elastance concept where the flow impediment is predicted to depend on myocardial elastic properties.

Animals↗
PubMed1995

A new solution for life without blood. Asanguineous low-flow perfusion of a whole-body perfusate during 3 hours of cardiac arrest and profound hypothermia.

BACKGROUND: The benefits of hypothermia for preventing ischemic injury are well known, but its application in surgery to protect the whole body during procedures requiring circulatory arrest is currently limited to < 1 hour at 15 degrees C using 50% hemodilution. In a significant departure from previous methods, we have developed a technique of asanguineous blood substitution with low-flow perfusion and cardiac arrest at < 10 degrees C in a canine model. Our approach has been to design a hypothermic blood substitute that would protect the brain and visceral organs during several hours of bloodless perfusion. Two different solutions have been designed to fulfill separate requirements in the procedure. METHODS AND RESULTS: With the use of extracorporeal cardiac bypass, 14 adult dogs were exsanguinated during cooling; 11 dogs were blood substituted using in combination the "purge" and "maintenance" solutions (group 1), and 3 dogs were perfused throughout with the "purge" solution alone as controls (group 2). After cardiac arrest, the solutions were continuously circulated for 3 1/2 hours by the extracorporeal pump (flow rate, 40 to 85 mL.kg-1.min-1; mean arterial blood pressure, 25 to 40 mm Hg). The temperature was maintained at < 10 degrees C (nadir, 6.6 +/- 0.1 degrees C) for 3 hours, and the hematocrit was kept at < 1% before controlled rewarming and autotransfusion. In the experimental group, the heart always started spontaneously in the temperature range of 11 degrees C to 27 degrees C, and 8 animals have survived long-term (current range, 14 to 110 weeks) without any detectable neurological deficit. In contrast, two control animals survived after extensive and aggressive cardiac resuscitation efforts; after surgery they exhibited transient motor and sensory deficits for approximately 1 week. Evaluation of biochemical and hematological parameters showed only a transient and inconsequential elevation in enzymes (eg, brain, liver, cardiac) in group 1 compared with the markedly greater elevations in group 2. For example, immediate postoperative values (mean +/- SEM) for lactate dehydrogenase were 114 +/- 10 for group 1 versus 490 +/- 210 for group 2 (P < .03); for SGOT, values were 93 +/- 18 for group 1 versus 734 +/- 540 for group 2 (P < .05). On day 1 for creatine kinase (CK), the group 1 value was 7841 +/- 2307 versus 71,550 +/- 2658 for group 2 (P = .03), and for CK-BB, the group 1 value was 108 +/- 22 versus 617 +/- 154 for group 2 (P = .03). Neurological evaluation using deficit scores (NDS) was based on a modification of the Glasgow Coma Scale score: 0, normal; 1, minimal abnormality; 2, weakness; 3, paralysis; 4, coma; and 5, death. At days 1 and 2 after surgery, NDS (mean +/- SEM) were 0 +/- 0 for the experimental group versus 1.5 +/- 0.5 for the control group. At days 3 and 7 after surgery, NDS were 0 +/- 0 for group 1 versus 1.0 +/- 1.0 for group 2. CONCLUSIONS: The faster neurological recovery of dogs treated with the "intracellular-type" maintenance solution supports the biochemical data showing the benefits of this type of blood substitute for extending the safe limits of hypothermic cardiac arrest procedures to > 3 hours.

Animals↗
PubMed2005

Efficacy of repeat isolated limb perfusions with tumor necrosis factor alpha and melphalan for multiple in-transit metastases in patients with prior isolated limb perfusion failure.

BACKGROUND: Isolated limb perfusion (ILP) is an effective treatment modality for multiple in-transit melanoma metastases confined to the limb. Recurrences after ILP, however, occur in approximately 50% of patients and are a challenge for further treatment. The efficacy of repeat ILPs to prolong local control in this patient category is evaluated in this article. METHODS: We used a prospective database in a tertiary referral center. Out of 100 tumor necrosis factor (TNF)-based ILPs with TNF and melphalan (TM-ILPs) in melanoma patients between March 1991 and July 2003, 25 repeat ILP procedures were performed in 21 patients in whom prior ILP treatment failed. All patients had bulky and/or numerous lesions and were treated with mild hyperthermic TM-ILP by using 2 to 4 mg of TNF and 10 to 13 mg/L of limb volume for the leg and arm, respectively. RESULTS: The complete response rate was 76%, a partial response occurred in 20%, and no change was recorded in 4%. There was no difference in the complete response rate or local toxicity between first and repeat perfusions. Local recurrence occurred in 72%; the median time to local progression was 14 months. The 5-year survival rate was 47%, which compares favorably with known survival rates of stage IIIA/AB patients. The median follow-up of the patients was 26 months. CONCLUSIONS: Patients who experience treatment failure after previous ILP treatment respond very well to repeat perfusion, and prolonged local control can thus be obtained. The subgroup of patients qualifying for repeat ILP represents a relatively favorable biological behavior of the melanoma.

Adult↗
PubMed1993

The role of nitric oxide derived from L-arginine in the control of steroidogenesis, and perfusion medium flow rate in the isolated perfused rat adrenal gland.

The present studies were designed to investigate the role of nitric oxide (NO) in the regulation of adrenocortical function, using the intact rat adrenal gland in situ, perfused with medium (Hank's balanced salt solution) containing a range of concentrations of L-arginine, the substrate for NO production. In addition, the effects of NG-nitro-L-arginine methylester (L-NAME), an inhibitor of NO production, were investigated. Results showed that L-arginine caused a dose-dependent increase in the flow rate of the perfusion medium through the adrenal gland. This effect was specific, as neither D-arginine nor L-lysine had an effect. The presence of L-NAME (5 mmol/l) in perfusion medium containing L-arginine caused a decrease in flow rate to levels in the absence of L-arginine. In the presence of concentrations of L-arginine up to 500 mumol/l, corticosterone secretion rates were also stimulated in a dose-dependent manner. Further studies, investigating the effect of L-arginine on the response to ACTH(1-24) stimulation, found that the percentage increase in flow rate, aldosterone secretion and corticosterone secretion caused by ACTH were not significantly different using media containing 230 mumol L-arginine/l or in the absence of L-arginine. These results suggest a role for NO derived from L-arginine in the regulation of basal levels of adrenal vascular tone in the rat isolated adrenal gland preparation. They do not suggest an obligatory role for NO in either the vascular or steroidogenic response to ACTH stimulation.

Adrenal Cortex Hormones↗
PubMed1975

Renal transplantation in the rat. III. The effect of colloidal and non-colloidal perfusates on the clearing of blood from the in vitro perfused rat kidney.

Rat kidneys were perfused in vitro with Perfadex (Gelin's solution) and a modified Collins' C3-solution with or without colloids. When the same flow rate was used the presence of 5% dextran 40, 5% albumin, or 10% albumin did not alter the clearing of 51Cr-tagged red blood cells. The main difference between the experimental groups was a significant increase in perfusion pressure when colloids were excluded from the perfusate. Results concerning the regional distribution of 51Cr-activity within the kidney are discussed.

Albumins↗
PubMed1981

Effects of dietary protein or amino acids in the perfusion medium on amino acid metabolism in perfused adult rat liver.

To elucidate the response of amino acid metabolism in the liver to dietary protein and plasma amino acids, the livers of adult rats fed on diet containing 10% (control) or 3% (low-protein) egg protein for 3 weeks were perfused for 120 min with amino acid-free medium in Experiment 1 or medium containing an amino acid mixture simulating that in plasma in Experiment 2. During perfusion about 40% of the free amino acids were lost from the liver in Exp. 1, and about 30% in Exp. 2. During this period, in Exp. 1 the releases of free amino acids and urea into the medium were 140 mumol and 2.52 mg, respectively, in the control group and 207 mumol and 1.10 mg respectively, in the low-protein group. Thus release was greater than decrease in free amino acids in the liver. Essential amino acids, particularly lysine and branched chain amino acids, were released preferentially. The results suggest that the amount of breakdown of liver protein in the two groups was similar, but that the nitrogen was mainly released as free amino acids in the low-protein group, and as urea in the control group. On the contrary, in Exp. 2 the amount of nitrogen released from the liver was comparable to the decrease in amino acids in the liver, and the releases of urea were also less, being 1.83 mg in the control group and 0.54 mg in low-protein group. The results show that amino acid metabolism in the liver is greatly affected by the nutritional state of the animal and the amino acid content of the perfusion fluid.

Amino Acids↗
PubMed1992

Phosphate free perfusion prevents washout of tissue creatine in Langendorff perfused rabbit heart.

Rabbit hearts were perfused with Krebs-Henseleit bicarbonate buffer supplemented with 15 mM glucose and 10 mU/ml of insulin +/- Pi. At the end of 60 min the hearts were freeze-clamped and the content of ATP, creatine phosphate, creatine, lactate, pyruvate, DHAP and 3-P glycerate were determined enzymatically in neutralized perchloric acid tissue extracts. The free cytosolic ADP and Pi and the cytosolic NAD+ redox and phosphorylation potentials were calculated from the measured metabolite concentrations. Pi free perfusion resulted in increased creatine, free cytosolic ADP and cytosolic phosphorylation potential, decreased calculated free Pi and no change in cardiac ATP and creatine phosphate content. The increase in the cytosolic phosphorylation potential was due to the lowering of cytosolic free Pi. The increase in ADP was due to the increase in creatine. The increase in creatine appeared to be due to an inhibition of creatine efflux from the heart during Pi free perfusion which was mediated by an enhanced Na+ electrochemical gradient.

Adenosine Diphosphate↗
PubMedDate not supplied

Pulse oximetry and perfusion index measurement to assess uterine perfusion and viability.

This study was designed to establish if pulse oximetry (O2Sat) and perfusion index (PI) could be used to assess the contribution that uterine and ovarian vessels make to the overall perfusion of the uterus. During routine hysterectomies, the O2Sat and PI were measured over the right and left uterine cornu. These measurements were taken before any vessels were ligated (baseline), after only the ovarian vessels were clamped and then after the uterine vessels were clamped. Clamping the ovarian vessels alone decreased the uterine O2Sat and PI by a statistically significant amount. Subsequent clamping of the uterine vessels produced further significant decreases in O2Sat and PI. We concluded that both pairs of vessels contribute almost equally to uterine perfusion and that there may be a role, particularly for O2Sat and possibly for PI variables, in determining the success of uterine and ovarian vessel reanastomosis in uterine transplantation.

Female↗
PubMed1989

[Increase of perfusion pressure at constant perfusion rate caused by low pH values].

One hind leg each of 20 rats was perfused by a buffer-electrolyte mixture at a rate of 1.2 ml/min. When the pH of the solution was lowered from 7.4 to 7.0 and, thereafter, to around 6.0, the mean perfusion pressure increased by 1.6 to 3.4 and 2.5 to 12.4 kPa, respectively. The higher values were obtained when the perfusate contained 2.5% dextran (m.w. 40,000). Swelling of endothelial cells and vasoconstriction are discussed as possible effector mechanisms.

Animals↗
PubMed1989

Brain tissue pH, oxygen tension, and carbon dioxide tension in profoundly hypothermic cardiopulmonary bypass. Comparative study of circulatory arrest, nonpulsatile low-flow perfusion, and pulsatile low-flow perfusion.

The pH, oxygen tension, and carbon dioxide tension of canine brain tissue were experimentally examined during profoundly hypothermic cardiopulmonary bypass. After core cooling, a 60-minute period of circulatory arrest was performed in group 1 (n = 8), a 120-minute nonpulsatile low-flow perfusion (25 ml/kg/min) in group 2 (n = 8), and a 120-minute pulsatile low-flow perfusion (25 ml/kg/min) in group 3 (n = 8). When the animal was rewarmed, the core temperature was raised to 32 degrees C. Brain tissue pH kept decreasing in group 1, but it showed a delayed recovery in group 2 and a rapid recovery in group 3 during core rewarming. Brain tissue oxygen tension decreased significantly in group 1. Brain tissue carbon dioxide tension increased irreversibly in group 1, increased to about 100 mm Hg and recovered to 89.9 +/- 15.3 mm Hg in group 2, and reached a plateau of about 85 mm Hg and recovered to 55.4 +/- 6.7 mm Hg in group 3. We concluded that a 120-minute period of nonpulsatile low-flow perfusion provides more protection from brain damage than a 60-minute period of circulatory arrest. Furthermore, pulsatile flow will increase the safety margin of cardiopulmonary bypass even if the flow rate is reduced to 25 ml/kg/min.

Animals↗
PubMed1989

Vascular resistance vs. perfusate osmolarity: the short term microvascular effect of hypotonic and hypertonic perfusion in the isolated kidney.

Vascular resistance changes were measured in response to alteration in perfusate osmolarity in isolated rabbit kidneys perfused at 10 degrees C. The data obtained were found to fit a simple mathematical model of the vascular resistance of the microcirculation in which it was assumed that variation in this parameter depended solely upon osmotic alterations in the size of the cells within and around the blood vessel walls. The model predicts that the volumetric changes due to the different osmolarities are produced in a tissue layer whose thickness is 30% relative to a fixed outer radius. This result is compatible with the hypothesis that the effects are predominantly due to changes of endothelial cell volume and other perivascular capillary cells. The analysis illustrates the significance of perfusate osmolarity as a determinant of vascular resistance, can be used to investigate the hemodynamic effects that occur during the introduction and removal of cryoprotective agents, and is relevant to the interpretation of results obtained with hypertonic solutions in blood volume restoration after hypovolemic shock.

Animals↗
PubMed1985

[Small intestine perfusion. The authors' own method for the simultaneous performance of biopsy and perfusion of the human small intestine].

The analysis of advantages and disadvantages of the technique and principles of the methods of small intestinal perfusion, used by various authors in the studies on resorption processes, provided grounds the authors to develop their own method. The system for infusion and aspiration by a combined probe is described. Details about the composition of perfusion solution, the technique of the study and calculation of resorption rate are reported. The advantages of the method are as follows: simultaneous performance of small intestinal glucose perfusion and biopsy of small intestine, good tolerance by the patients and availability of the elements needed for the construction of the probe and system for infusion and aspiration. The mean glucose resorption rate was 814,07 mumol/min/30 cm in 9 subjects with no small intestinal diseases and with normal histomorphological picture of small intestinal mucosa.

Biopsy, Needle↗
PubMed1984

Blood leakage and melphalan leakage from the perfusion circuit during regional hyperthermic perfusion for malignant melanoma.

In regional hyperthermic perfusion with melphalan for patients with malignant melanoma of the leg, plasma leakage between the perfusion circuit and the systemic circulation was 4-7 ml X min-1. The melphalan concentration in the perfusate was biphasic, with half-lives of 8-12 mins for the initial phase and 19-28 mins for the second phase, after the first dose. After a second dose, the corresponding values were 11-13 and 26-34 mins. The highest concentration in general circulation was 0.38 micrograms X ml-1.

Chemotherapy, Cancer, Regional Perfusion↗
PubMed1999

Multislice perfusion and perfusion territory imaging in humans with separate label and image coils.

An arterial spin labeling technique using separate RF labeling and imaging coils was used to obtain multislice perfusion images of the human brain at 3 T. Continuous RF irradiation at a peak power of 0.3 W was applied to the carotid arteries to adiabatically invert spins. Labeling was achieved without producing magnetization transfer effects since the B1 field of the labeling coil did not extend into the imaging region or couple significant power into the imaging coil. Eliminating magnetization transfer allowed the acquisition of multislice perfusion images of arbitrary orientation. Combining surface coil labeling with a reduced RF duty cycle permitted significantly lower SAR than single coil approaches. The technique was also found to allow selective labeling of blood in either carotid, providing an assessment of the artery's perfusion territory. In normal subjects, these territories were well-defined and localized to the ipsilateral hemisphere.

Artifacts↗
PubMed1991

Regional cycles of perfusion and non-perfusion in the lung of the term fetal rabbit.

The spatial distribution of pulmonary blood flow and its change over time was investigated in term fetal rabbits, using the plasma tracer fluorescein-isothiocyanate-labeled bovine serum albumin (FITC-BSA). A tracer bolus was injected intravenously and allowed to circulate in vivo for increasing periods of time (2-30 minutes) prior to arrest of the circulation and tissue preparation. Initially, fluorescence was present in the vasculature of 43% of lung parenchymal tissue, disposed as discrete regions or "lobules." Interspersed regions of lung tissue received no tracer inflow. With increasing tracer circulation times (10, 20, and 30 minutes), a greater percentage of lung cross-sectional area contained vessels exhibiting tracer fluorescence (64, 96, and 100%, respectively). In the fetal lung, a high pulmonary vascular resistance (PVR) is maintained. Our studies indicate that, at any given moment, fetal pulmonary blood flow is distributed only to a proportion of discrete lung "lobules," while interspersed "lobules" receive no flow at all. The "lobules" alternate between these "high" and "low" vascular resistance states with a periodicity of approximately 35 minutes, comprising 22 minutes of non-perfusion followed by 13 minutes of perfusion. This circulatory pattern permits both the maintenance of high PVR and uniform lung development. Further, by directing flow to only a portion of the vasculature, greater microvascular flow rates are achieved and hence the risk of blood sludging and stasis is reduced. Recruitment of these "non-perfused" regions at birth could thus produce a significant reduction in PVR.

Animals↗
PubMed1984

Comparison of cytologic and biochemical properties between liver cells isolated from adult rats by trypsin perfusion and those isolated by collagenase perfusion.

Primary cultures of liver cells isolated from adult rats by trypsin and collagenase perfusion techniques were carried out to compare cytologic and biochemical properties between the differently prepared cells. Trypsin-dispersed cells consisted of comparatively smaller cells, whereas collagenase-dispersed cells consisted of larger cells. The cell attachment efficiency on culture day 1 was about twice as high in the liver cells prepared with collagenase than those prepared with trypsin. Mature hepatocytes isolated by collagenase perfusion could be maintained in the primary culture for a longer period than those isolated by trypsin perfusion. Epithelial-like clear cells started to grow much earlier in the primary culture of the trypsin-dispersed liver cells than in that of the collagenase-dispersed liver cells. Earlier proliferation of epithelial-like clear cells could not be induced by in vitro trypsinization of the collagenase-dispersed liver cells. Both kinds of enzymatically prepared liver cells showed albumin production and exhibited glucose 6-phosphatase (D-glucose-6-phosphate phosphohydrolase, EC 3.1.3.9, G6Pase) and tyrosine aminotransferase (L-tyrosine: 2-oxoglutarate amino-transferase, EC 2.6.1.5, TAT) activities for 1 week in the primary culture. Albumin production was higher in the liver cells prepared with collagenase than those prepared with trypsin, whereas G6Pase activity was almost the same between them. TAT activity up to culture day 2 was about 3-fold higher in the liver cells prepared with collagenase than in those prepared with trypsin. Combined supplementation of dexamethasone (1 X 10(-5)M) and insulin (10 micrograms/ml) consistently improved the cell attachment efficiency and was very effective in the maintenance of mature hepatocytes in both types. Furthermore, these hormones enhanced the albumin production and TAT activity in both types.

Albumins↗
PubMed2003

Monitoring of cerebral perfusion pressure during intracranial hypertension: a sufficient parameter of adequate cerebral perfusion and oxygenation?

OBJECTIVE: A cerebral perfusion pressure (CPP) oriented treatment is a widely accepted standard for patients with intracranial hypertension. In an animal model of controlled intracranial hypertension we investigated whether CPP is a reliable parameter of sufficient cerebral perfusion and oxygenation. Using near-infrared reflexion spectroscopy the effect of decreasing CPP due to increasing intracranial pressure (ICP) on cerebral tissue oxygenation was studied. METHODS: Ten rabbits were subjected to artificially elevated ICP using the cisterna-magna infusion technique. Regional cerebral O(2) saturation of hemoglobin (tiSO(2)), regional tissue concentration of hemoglobin (tiHb), and CPP were recorded continuously. CPP was investigated with respect to tiSO(2). Electrocortical activity was simultaneously recorded by two-channel EEG to determine the onset of ischemia. RESULTS: Reduced CPP due to increased ICP led to a continuous decrease in tiSO(2.) There was progressive suppression of EEG frequency and amplitude with decreasing CPP in all animals. Onset of EEG-silence due to elevated ICP was observed in a wide range of CPP-values between 9 and 42 mmHg. At the same time tiSO(2) varied merely between 0 and 5%. CONCLUSIONS: Regarding the EEG effects due to increased ICP (EEG silence), CPP values showed a wide interindividual variability, in contrast to tiSO(2). In our animal model the sole calculation of CPP did not reflect adequate cerebral perfusion.

Animals↗
PubMed2006

Stress-induced abnormalities in myocardial perfusion imaging that are not related to perfusion but are of diagnostic and prognostic importance.

INTRODUCTION: Certain stress-induced ancillary findings on myocardial perfusion scintigraphy increase the likelihood that the patient has coronary artery disease (CAD); furthermore, among CAD patients, they indicate more severe and extensive disease, placing these patients at higher risk for future cardiac events. Indeed, in studies with no obvious perfusion defect yet with serious CAD--for example, balanced ischemia--it can be these high-risk findings that necessitate invasive intervention. DISCUSSION: Besides reversible perfusion defects, such findings include increased pulmonary radiotracer uptake, transient cavity dilatation, increased end-diastolic or end-systolic volume, decreased post-stress ejection fraction, and increased right ventricular tracer uptake on stress images. The pathophysiology underlying these findings is clearly different as they do not always occur together, and each independently predicts more severe and extensive CAD. In the current review, these findings are defined and their significance in diagnosing patients with suspected or known CAD is discussed.

Cardiomyopathies↗