CLOSED PELVIC PERFUSION: ISOLATION PERFUSION OF THE PELVIS WITHOUT CELIOTOMY.
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Catheterization↗
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Effect of plasma from essential hypertensives on vascular tone of aortic strips, isolated perfused mesentery and isolated perfused kidney.
Different vascular models of normotensive Wistar rats, including aortic strips, isolated perfused mesentery and isolated perfused kidney, were used to study hemodynamic effects of plasma fractions obtained by gel filtration from the blood of essential hypertensive and normotensive subjects. Plasma fractions from essential hypertensives studied had been shown to increase blood pressure after intravenous injection in rats. In the aortic strips, 50 microliters of a hypertensive fraction (HF) elicited a calcium-dependent contraction of 0.14 +/- 0.035 mN (n = 20, p less than 0.05), which was inhibited by nifedipine, whereas tension of the strips was not significantly changed by normotensive fractions (NF) (n = 17). In the isolated perfused mesentery preparation, no significant change of perfusion pressure by HF or NF could be demonstrated (n = 10). In the isolated perfused kidney, a transient increase of perfusion pressure was induced by HF (19.5 +/- 16.6 mm Hg, n = 40, P less than 0.001) but not by NF. This increase was abolished in calcium-free, 2 mmol/l EGTA containing perfusion medium. The response was diminished, but not abolished by nifedipine. These data demonstrate vasopressor properties of plasma from essential hypertensives, which might be the consequence of a circulating vasoconstrictor substance in the blood of essential hypertensives.
Adult↗
The isolated perfused porcine liver: assessment of viability during and after six hours of perfusion.
Isolated liver perfusion was developed for the study of liver physiology and preservation. The recent development of new perfusion devices and appropriate liver preservation solutions prompted us to reconsider liver perfusion for the specific purpose of evaluating viability in terms of biochemical changes, paying special attention to modifications in the histological ultrastructure. Twenty-two isolated pig livers were perfused with autologous blood. Arterio-portal perfusions were carried out using an extracorporeal perfusion circuit with a hollow fibre membrane oxygenator. Four groups of pig livers were studied using three different liver flushing solutions [Ringer's lactate, ELOHES, and University of Wisconsin (UW)] and two different oxygenation modalities. Liver function tests and histological studies were done. Our results revealed that a high partial oxygen pressure (PO2) level was deleterious to the ultrastructural elements of hepatocytes, in particular to the mitochondria. It was also associated with deficient metabolic performance, i.e., poor bile production and lack of aerobic metabolism. Normal blood gas values could be obtained with the use of air for liver oxygenation. Flushing of the liver with Ringer's lactate or a macromolecular solution such as ELOHES was associated with severe liver cell injuries, as reflected by a marked rise in liver enzymes and histological lesions. Satisfactory results were obtained when UW solution was used for liver harvesting. We conclude that an appropriate liver preservation solution, normal blood gas values, and normal physiological arterio-portal pressure and blood flow are essential for appropriate liver function with preservation of liver architecture and of hepatocyte ultrastructures. Total bilirubin in bile and Factor V are sensitive indicators of good liver function.
Animals↗
Serial fluorometric assessments of skin perfusion in isolated perfused human skin flaps.
The applicability of serial skin surface fluorometry for repeated assessments of skin flap perfusion was investigated using the isolated perfused human transverse paraumbilical (TP) skin flap model. The flow rate, perfusion pressure and skin surface temperature were kept constant in seven human TP skin flaps and a low dose of fluorescein (3 x 10(-5) M) was used for each assessment. It was observed that the mean values for total dye fluorescence measured by a fluorometer and the maximum distance of perfusion estimated by dye fluorescein index remained consistent in five repeated assessments at 15 min interval. The variation in the maximum distance of perfusion within each TP skin flap over 5 repeated assessments was also relatively small, as judged by the mean coefficient of variation (6.1%; SEM 0.4%). Furthermore, a highly significant correlation between microsphere (15 microns) radioactivity index and dye fluorescence index was observed at corresponding locations in these seven TP skin flaps (r = 0.81; p < 0.001, n = 75). Taken together, these observations indicate that serial skin surface fluorometry provided consistent repeated assessments of skin perfusion in human skin flaps in vitro and the dye fluorescence index provided a consistent assessment of skin perfusion distance along the length of the TP skin flap. These observations lead us to speculate that critical (threshold) dye fluorescence index determined at various postoperative time points should be useful for prediction of skin viability in clinical skin flaps; thus, a clinical investigation is recommended.
Acetylcholine↗
Development and evaluation of a new apparatus for continuous perfusion of isolated perfused pig heart.
To develop a better model of isolated perfused heart, a new apparatus of coronary artery cannula- fixed-in-aortic tube was developed for continuous normothermic perfusion and compared to the Casalis apparatus with cold ischemia. Eight mongrel pigs with the body weight of 18 to 24 kg were divided half into two groups. All the continuous perfusion experimental hearts resumed a spontaneous heart beat and stabilized earlier than the control hearts without the need of defibrillator or pacemaker, indicating no reperfusion injury on the heart. All the experimental hearts did not show fibrillation nor stopped beating during the entire experiment, whereas the control hearts fibrillated. Two control hearts stopped beating, and only one of the two survived with the help of pacemaker.The coronary systolic, diastolic, and mean pressures were more stable with low variation in the experimental hearts than the cold ischemic control hearts. The experimental hearts consumed more oxygen than the control hearts, indicating more cardiac output. According to these results, the continuous normothermic perfusion method by the new cannula, even though with a short-period of hypothermic perfusion, provided better myocardial protection than the cold ischemia.
Animals↗
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↗
Cholyl-lysylfluorescein: synthesis, biliary excretion in vivo and during single-pass perfusion of isolated perfused rat liver.
A fluorescent bile salt, cholyl-lysylfluorescein (cholyl-lys-F), was synthesised so that it retained both an intact steroid ring and a side chain structure with an unblocked carboxyl group. Its biliary kinetics and hepatic extraction were studied in Wistar rats and in the isolated perfused rat liver, respectively. The synthetic method used excess N-epsilon-CBZ-l-lysine methyl ester hydrochloride (7 mmol) and cholic acid (5 mmol) via EEDQ with a yield of 94% for cholyl-lys. Cholyl-lys-F was synthesized employing equimolar amounts of cholyl-lys (sodium salt) and fluorescein isothiocyanate (FITC) in bicarbonate buffer (pH 9.5) over 16 h at room temperature (21 degrees C) with a yield of 70%. The fluorescent property of cholyl-lys-F was similar to fluorescein with a strong apple-green fluorescence. In bile-fistula rats under pentobarbital anaesthesia, the cumulative 20 min biliary excretion as a percentage of injected dose were as follows: cholyl-lys-F, 94.4 +/- 0.3%, [14C]cholylglycine (CG), 93.1 +/- 1.2% and fluorescein (F), 34.8 +/- 0.5. Furthermore the single-pass hepatic extraction of cholyl-lys-F was 64.1 +/- 3.9%, [14C]CG was 66.1 +/- 1.2% and F was 16.5 +/- 2%. The similarity in biliary output and hepatic extraction of cholyl-lys-F to that of the natural bile acid cholylglycine suggest that both compounds are handled in a similar fashion. The greater biliary excretion and hepatic extraction of cholyl-lys-F relative to free fluorescein further suggest that conjugation with a bile salt may be an efficient way of targeting compounds to the liver.
Animals↗
Effect of spontaneous diabetes on hormone release in BB/Phi rats: comparison between the isolated perfused pancreas/stomach/duodenum/spleen and the isolated perfused pancreas.
We have studied the effects of spontaneous diabetes in BB/Phi rats on hormone release in response to amino acids (15 mM) and to amino acids (15 mM) plus glucose (10 mM) from isolated perfused pancreas/stomach/duodenum/spleen (PSDS) and from isolated perfused pancreas (P) preparations. In the PSDS preparation, diabetes reduced total integrated insulin output by 97% (from 1146 +/- 198 to 40 +/- 24 ng/65 min, P less than 0.001), and glucagon output by about 50% (from 51.6 +/- 13.1 to 24.0 +/- 3.7 ng/65 min, P less than 0.05), whereas somatostatin output did not change (105.5 +/- 48.1 to 110.1 +/- 36.9 ng/65 min). In the P preparation, integrated glucagon output fell by 91% (from 97.9 +/- 26.8 to 8.6 +/- 4.8 ng/65 min, P less than 0.01) whereas integrated somatostatin output more than doubled (from 28.1 +/- 7.5 to 69.6 +/- 14.2 ng/65 min, P less than 0.05). Intestinal glucagon and somatostatin contributions were estimated by comparing hormone release from the PSDS with that from the P preparations. We conclude that in our nondiabetic BB/Phi rats, the pancreas was the only source for the release of glucagon and that the intestinal tract secreted more somatostatin than the pancreas. In the diabetic BB/Phi rats, pancreatic glucagon and insulin release was virtually abolished while glucagon secretion from the intestinal tract increased and somatostatin secretion decreased.
Animals↗
Studies on the morphology of the isolated perfused rabbit ovary. I. Effect of long-term perfusion.
Isolated ovaries from untreated, sexually mature rabbits were introduced into an in vitro perfusion system and perfused with a chemically defined medium containing albumin. The ovaries were perfused for up to 15 h (mean 11.5 h) and then processed for morphological investigation. Both at the light- and electron-microscopical levels, most of the ovaries exhibited a normal structure comparable with ovaries in situ. In two cases, however, marked accumulations of bacteria were found, although not inside the follicles. Since ovulation in the rabbit normally occurs between 9.5-13 h after mating or human chorionic gonadotrophin treatment, this model seems adequate for studies of ovulation in vitro. It is, however, important to study the ovaries microscopically after the perfusion to detect artifacts, e.g., bacterial infection, that may have influence on the process of ovulation.
Animals↗
[COMPARATIVE STUDIES ON THE DISTRUBITION OF ALBUCID FOLLOWING ITS INTRA-ARTERIAL INFUSION AND ISOLATION PERFUSION OF ISOLATED PELVIC ORGANS UNDER EXPERIMENTAL CONDITIONS].
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Antineoplastic Agents↗
Effects of stroma-free hemoglobin solutions on isolated perfused rabbit hearts and isolated perfused rat kidneys.
"Stroma-free" hemoglobin solutions (SFH) cause hemodynamic alterations indicative of vasoconstriction. We studied vasoconstrictor activity in isolated rabbit hearts and rat kidneys of unmodified SFH and of SFH modified by pyridoxylation or glyoxylation, with or without glutaraldehyde cross-linking. The purity and chemical composition of the solutions, all prepared by other laboratories, were not characterized by us. In isolated hearts SFH prepared by conventional methods had potent vasoconstrictor activity. Pyridoxylation or purification by ion exchange chromatography did not alter the constrictor activity. Decreased constrictor activity was observed with human SFH cross-linked by glutaraldehyde treatment, or purified by affinity chromatography, and with bovine SFH purified by ultrafiltration and preparative HPLC. In isolated kidneys modified and unmodified SFH increased renal vascular resistance and decreased glomerular filtration rate with no morphologic evidence of tubular damage.
Animals↗
Influence of anabolic hormones on protein metabolism in the isolated perfused rat hind limb: a technique for cyclic cross-perfusion of isolated limb and liver.
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Animals↗
Biliary excretion of apolipoprotein B by the isolated perfused rat liver. Relationship to receptor-mediated uptake of human low-density lipoprotein and biliary lipid secretion.
Since we previously reported that apolipoproteins, the lipid transport proteins of lipoproteins, are present in human bile, we tested the hypothesis that apolipoproteins in bile are derived from circulating lipoproteins and that they are involved in the biliary excretion of lipids. We perfused isolated rat livers with lipoprotein-free solutions and collected bile before and after addition of human low and high density lipoproteins. When human low density lipoprotein was added to solutions perfusing livers isolated from rats previously treated with ethinyl estradiol, a hormone that increases receptor-mediated uptake of low density lipoproteins by hepatocytes, the concentrations in bile of cholesterol and phospholipid, but not bile acids, increased by approximately 25% together with the appearance of small amounts (approximately 1% of the amount perfused) of a metabolized form of human apolipoprotein B in bile. Acetylation of low density lipoprotein, a procedure that prevents this lipoprotein from binding to its receptor on hepatocytes, both abolished the appearance of immunoreactive apolipoprotein B in bile and blocked the increase in biliary cholesterol and phospholipid concentrations. Whereas the addition of a high density lipoprotein to solutions perfusing isolated livers of normal rats was associated with the appearance of small amounts (approximately 1% of the amount perfused) of apolipoproteins A-I and A-II in bile, there were no accompanying changes in the concentrations of biliary lipids. These results suggest that apolipoproteins or their fragments in bile are derived from circulating lipoproteins; in the case of apolipoprotein B, biliary excretion is dependent upon receptor-mediated uptake of low density lipoprotein by the hepatocyte. Our data are also consistent with the hypothesis that certain apolipoproteins may be involved in biliary lipid secretion, although in an as yet unclear manner.
Animals↗
Phalloidin uptake by the liver of cholestatic rats in vivo, in isolated perfused liver and isolated hepatocytes.
Rats made cholestatic by bile duct ligation survive phalloidin poisoning. This protection against phalloidin poisoning is correlated with the rate of the toxin uptake by the liver. [3H]demethylphalloin was used as a tracer for uptake studies. This is justified because there is no significant difference in the rate of uptake of the phallotoxins used. Within 4 h after bile duct ligation phalloidin uptake is reduced to about 25% and after 24 h to about 15% of controls. Isolated perfused livers and isolated hepatocytes from cholestatic rats bind less phalloidin than normal controls. Besides morphological changes serum factors may account for the decreased rate of phallotoxin uptake in cholestatic cells.
Alkaloids↗
Vasoreactivity of Fluosol perfluorocarbon emulsion vs. Earl's balanced salt/albumin perfusates in the isolated perfused rat lung.
We compare the vasoreactive responses of Fluosol perfluorocarbon emulsion versus Earl's balanced salt+albumin solution as perfusates in an isolated perfused rat lung. Comparisons were made with three separate vasoconstrictive stimuli: norepinephrine, and prostaglandin F2 alpha dose-response analysis, and generation of hypoxic pulmonary vasoconstriction. The hypoxia experiments were also performed with N-nitro-arginine added to the perfusates to block production of endogenous nitric oxide prior to the application of hypoxic ventilation challenge. The vasoconstrictive effects of norepinephrine, PGF2 alpha and hypoxia were significantly depressed in the perfluorocarbon perfused versus salt/albumin solution perfused lungs. With the addition of NNA to the perfusates, hypoxic pulmonary vasoconstriction is enhanced in both Earl's/albumin perfused as well as in the fluorocarbon perfused lungs. We can conclude that the pulmonary vasoconstrictive effects of norepinephrine, PGF2 alpha, and hypoxia are depressed in perfluorocarbon emulsion perfused, compared to salt-albumin solution perfused lungs. It is possible that perfluorocarbon emulsions interfere with normal endothelial function. As such, these compounds may be useful in examination of normal and abnormal endothelial function in various research applications.
Albumins↗
Oxyntomodulin (glicentin-(33-69)): pharmacokinetics, binding to liver cell membranes, effects on isolated perfused pig pancreas, and secretion from isolated perfused lower small intestine of pigs.
The pharmacokinetics of purified synthetic oxyntomodulin were studied after infusing it into euglycaemic pigs at two rates. The elimination of the peptide from plasma was characterized by two components, a fast one (t1/2 7.2 +/- 0.6 min) and a slow one (t1/2 20.4 +/- 3.8 min) (mean +/- S.E.M., n = 7). The metabolic clearance rate was independent of infusion rate (6.96 +/- 0.99 vs 7.44 +/- 0.98 ml/kg . min (mean +/- S.E.M., n = 7). The synthetic peptide bound to pig hepatic glucagon receptors, but with approximately 2% of the affinity of glucagon, and showed insulinotropic and somatostatinotropic effects when infused into isolated perfused pig pancreases at concentrations higher than 10(-10) M. A dose-dependent increase was also shown for pancreatic glucagon output. A naturally occurring peptide, identified as oxyntomodulin by gel filtration and HPLC, was released into the circulation from the pig lower small intestinal mucosa upon intraluminal administration of glucose, and represented 25 +/- 3.8% of the secreted glucagon-like immunoreactivity. 11 +/- 2.3% of the secreted glucagon-like immunoreactivity was indistinguishable from glucagon itself upon gel filtration; thus at least 36% of the glucagon-like immunoreactivity secreted from the intestinal mucosa is already in an active form.
Animals↗
Effects of atrial natriuretic peptides on metabolism of arginine vasopressin by isolated perfused rat kidney.
Atrial natriuretic peptide (ANP) antagonizes the release and action of arginine vasopressin (AVP) both in vivo and in vitro. We have reported that ANP increases the urinary and metabolic clearances of AVP in normal subjects (A. M. Moses et al. J. Clin. Endocrinol. Metab. 70: 222-229, 1990). To clarify this effect, we perfused isolated rat kidneys in vitro and measured the clearances of AVP for 30 min after the addition of rat ANP [rANP-(1-28), 10(-7) M]. In the perfused kidney, rANP increased the urinary clearance of AVP (UCAVP) from 321 +/- 19 to 417 +/- 20 microliters/min (P less than 0.01) and increased the glomerular filtration rate (GFR) from 558 +/- 28 to 696 +/- 28 microliters/min (P less than 0.01). Fractional excretion of AVP was unchanged. Rates of AVP reabsorption were directly related to filtered AVP, and this relationship was not altered by ANP. ANP did not affect the total organ clearance or the renal metabolic clearance of AVP. The increase in GFR was associated with increases in renal vascular resistance (P less than 0.05), filtration fraction (P less than 0.01), and sodium excretion (P less than 0.001). UCAVP also increased when GFR was raised without ANP by perfusing at higher pressures. The rat ANP clearance receptor agonist [cANP- (4-23), 10(-7) M] did not change GFR or UCAVP. ANP increases UCAVP in the isolated perfused rat kidney. This appears to be a hemodynamic effect of ANP, acting through its biological receptor and not the clearance receptor.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
The isolated perfused lung--a critical evaluation.
Recent refinement and application of the technique of perfusing isolated intact lung preparations from suitable experimental animal has enhanced our knowledge of the non-respiratory functions of the lung. The technique consists of perfusion with whole blood or constituted media via pulmonary artery or artificially ventilated lungs. Such preparations have been known to be especially useful for studies of uptake, metabolism and disposition of exogenous and endogenous substances. Recent advances in unilateral, split-lung perfusion in which left and right lungs are unilaterally perfused simultaneously have enabled investigators to maintain paired controls during perfusion. Such techniques are useful in the study of the interactions of endogenous and exogenous chemicals in the lung tissue. Differences between subcellular or lung slice preparations and intact lung perfusion are to be expected on the basis of distorting natural vascular and extra-vascular barriers in the case of in vitro preparations. Areas in which perfused lungs have not been extensively used include uptake and disposition of gases, solvents and vapors, effects of toxic chemicals on respiratory and non-respiratory functions of the lung and alteration of pulmonary mechanisms and hemodynamics in the presence of interacting chemical or physical stimuli. With suitable modifications, application of isolated perfused lung preparations for these investigations should be technically feasible in the future.
Animals↗