Application of a quantitative spectrophotometric endotoxin assay on lymph and plasma from the rat

A quantitative spectrophotometric assay for endotoxin, utilizing Limulus amebocyte lysate and a chromogenic peptide substrate, was standardized for the application on lymph and plasma from the rat. The influence of inhibitors and unspecific amidolytic activity, the optimal incubation times, the adhesion of endotoxin to platelets and glass surface, the variation in endotoxin standard as well as the effects of cold storage on endotoxin activity were settled. In vitro added as well as endogenously derived endotoxin was studied. The method was found to be reliable when in practical use on these media.

Secretion of apolipoproteins in the suckling rat. Absence of low-molecular-weight apolipoprotein B of hepatic origin

Synthesis of apolipoprotein B in the intestine and liver in suckling rats whose duodena had been infused with [3H]lysine was estimated by measuring the radioactivity in the mesenteric lymph and blood serum. Apolipoprotein B synthesized in the suckling rat intestine was an exclusively low-molecular-weight form. In the serum d less than 1.21 g/ml fraction obtained from the lymph-diverted rats, apolipoprotein B of high molecular weight was only labeled with [3H]lysine in suckling rats, whereas both forms of apolipoprotein B were labeled in the adult rats. These results suggest developmental changes in hepatic apolipoprotein B synthesis and secretion.

Relationship of increased lung serotonin levels to endotoxin-induced pulmonary hypertension in sheep. Effect of a serotonin antagonist

A persistent pulmonary artery hypertension, increased airways resistance, increased vascular permeability to protein, and hypoxia are characteristic of sepsis-induced ARDS in humans and are present in the late phase injury response seen in sheep after endotoxin. Our purpose was to determine the role of serotonin, 5-HT, in the steady-state pulmonary hypertension and decreased arterial oxygen tension seen beginning approximately 3 h after Escherichia coli endotoxin injury (2 micrograms/kg) in the adult sheep. Plasma 5-HT levels remained constant, whereas lung lymph values increased from a baseline of 60 +/- 40 to 180 +/- 70 and 270 +/- 90 ng/ml at 1-h and at 3- to 5-h periods, respectively, after endotoxin. Platelet count decreased significantly only at the 3-h time period. Ketanserin, a 5-HT antagonist, was infused (0.15 mg/kg/h) in 7 sheep during endotoxin injury. The degree of early pulmonary hypertension and hypoxia was not affected by ketanserin. Mean values for pulmonary artery pressure and arterial oxygen tension were 40 +/- 8 mmHg and 70 +/- 8 torr for endotoxin alone and 38 +/- 7 mmHg and 72 +/- 7 torr for the ketanserin group. Steady-state, protein-rich pulmonary perfusion was also not altered, being increased 3-fold in both groups. Pulmonary hypertension and hypoxia were significantly attenuated, however, at the 3- to 5-h period with ketanserin, compared with endotoxin alone, the pulmonary artery pressure decreasing from 29 +/- 5 to 22 +/- 4 mmHg and the PaO2 increasing from 75 +/- 4 to 83 +/- 5 torr.(ABSTRACT TRUNCATED AT 250 WORDS)

Fractionation of chylomicrons by heparin-sepharose chromatography. Characterization of two heparin-binding proteins

Rat lymph chylomicrons were separated into two fractions using heparin-Sepharose chromatography: a major fraction which elutes from the column with the void volume at 0.05 M NaCl, and a smaller fraction which binds to the column at 0.05 M NaCl and elutes at 0.3 M NaCl. These two fractions differ in mean particle size, and lipid and protein compositions. Both fractions share apolipoproteins B, A-IV, E, A-I, and C, but the fraction which binds to heparin-Sepharose contains two additional proteins: protein I (Mr = 6.0 X 10(4)), and protein II (Mr = 8.0 X 10(4)). Both proteins are also present in the lipoprotein-free fraction of rat serum. Proteins I and II bind to heparin-Sepharose, and are highly amphiphilic: they bind with high affinity to phospholipid surfaces and form stable monolayers at the air-water interface. The molecular weight, amino acid composition, heparin binding, and amphiphilicity of protein I resemble that of beta 2-glycoprotein I; in addition, protein I from rat lymph chylomicrons cross-reacts with rabbit antiserum to human beta 2-glycoprotein I, suggesting that these two proteins are homologous. Protein II appears to be a previously undescribed protein. The possible functions of these two proteins are discussed.

The pulmonary hypertension of sclerosing agents is prevented by cyclooxygenase inhibitors

Sodium morrhuate and sodium tetradecylsulfate are injected during endoscopic sclerotherapy to control variceal bleeding. When administered to sheep they cause transient pulmonary hypertension and increase protein poor lung lymph flow. To determine the etiology of these alterations, we studied three groups of sheep after establishing acute lung lymph fistulas. In Group 1, indomethacin or ibuprofen was infused. In Group 2, 2.5 cc of sodium morrhuate was injected alone (2A) or after indomethacin or ibuprofen pretreatment (2B). In Group 3, 2.5 cc of sodium tetradecylsulfate was given intravenously either alone (3A) or after indomethacin or ibuprofen (3B). When sclerosing agents were given alone (Group 2A and 3A) pulmonary artery pressures increased three-fold at 30 seconds postinjection to 37 +/- 4.4 and 39 +/- 5.7 mmHg respectively with a slow return to baseline over two hours. Lymph flow increased significantly from 1.3 +/- 1.5 to 2.7 +/- 1.5 cc/30 minutes after sodium morrhuate and from 1.2 +/- .62 to 2.7 +/- 1.7 cc/30 mins at 30 minutes after sodium tetradecylsulfate and the lymph/plasma albumin ratio fell. Increased lymph flow persisted through 120 minutes. In those animals receiving a sclerosing agent after indomethacin or ibuprofen (2B and 3B) there was no change in pulmonary artery pressure, lymph flow, lymph plasma albumin ratio, or lung wet weight to dry weight ratios. We conclude that the pulmonary hypertension and increased protein poor lymph flow are mediated by prostaglandins.

High performance liquid chromatographic determination of cyclosporin A in body fluids

A sensitive, specific and reproducible high performance liquid chromatographic assay method for the determination of a new immunosuppressant, cyclosporin A (CsA), in the biological samples such as human blood, rat plasma and rat lymph has been developed. CsA was extracted with diethyl ether followed by being cleaned up with liquid-liquid extraction procedure using carbon tetrachloride-methanol system, and was chromatographed on a microparticulate CN column with UV detection at 212 nm. The lower detection limit is 100 ng/ml in human blood (from 1.0 ml) and 500 ng/ml in the rat plasma or lymph (from 0.2 ml). This method is sensitive enough for monitoring CsA concentrations in the renal transplant patients in the therapeutic dose range, and is also applicable to the determination of CsA in the rat plasma and lymph samples for the purpose of pharmacokinetic evaluation of several CsA dosage forms in the rats.

[Rate of lymph flow and the protein-electrolyte composition of the lymph from the thoracic duct in experimental acholia]

Experimental acholia was reproduced by applying a biliary fistula to the choledochus in cats for 20 days. It was established that acholia was accompanied by considerable changes in the lymph flow and in the protein-electrolyte composition of the lymph. The rate of the lymph flow in animals with acholia was more than 2 times as decreased as compared with control. The electrolyte and protein shifts in the lymph during acholia were manifested by the reduction in the lymph protein and K+ content.

Lymph flow, lymph protein concentration, and protein output from rat small intestine

Lymph flow (JL), lymph protein concentration (CL), and protein output (JP) from the main intestinal lymph duct were determined. The basal JL from the mesenteric pedicle alone was the same as that from the mesenteric pedicle attached with a segment of the nonabsorbing intestine, indicating that the basal JL does not originate from the intestine but is totally from the region of the mesenteric pedicle. The basal CL was 3.5-3.8 g/100 ml. When the intestine was absorbing water, JL increased and CL decreased, but JP increased above the basal JP in the initial 20 min of water absorption and then decreased progressively with time. Furthermore, it was estimated that CL in the "excess lymph" (formed during water absorption) was 1.4 +/- 0.2 g/100 ml in the initial 10 min of water absorption and was zero or nearly so in the later periods. From this and other evidence, it is concluded that under various conditions without net water absorption rat small intestine does not produce lymph and that during water absorption there is no significant increase in capillary permeability or capillary filtration. Therefore, the excess lymph could be mostly derived from the fluid absorbed from the lumen of the intestine.

Intestinal absorption of 1,25-dihydroxyvitamin D3 in the rat

Intestinal absorption of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] from in vivo jejunal sacs was studied in rats with thoracic duct and bile duct cannulas. In 6 h 86.5% of the administered 1,25(OH)2D3 was absorbed, but only 7.3% was recovered in thoracic duct lymph. Appearance in plasma of [3H]-1,25(OH)2D3 after intrajejunal administration was identical in rats with and without diverting lymph cannulas, indicating that the 1,25(OH)2D3 is absorbed almost entirely via portal blood. When 1,25(OH)2D3 was instilled into the jejunum in a fat suspension without bile salts rather than a mixed micellar solution, less was recovered in lymph, but total intestinal absorption was unchanged. High-pressure liquid chromatography of a lymph extract demonstrated that 1,25(OH)2D3 was present only as the unchanged secosteroid. In lymph, only 4.1% of the 1,25(OH)2D3 was in the chylomicrons, with the remainder bound to the plasma protein fraction of lymph. Treatment of rats with cycloheximide to block chylomicron synthesis did not decrease absorption of 1,25(OH)2D3. These results indicate that intestinal absorption of 1,25(OH)2D3 is effective and not very dependent on luminal bile salts. Almost all 1,25(OH)2D3 is released from the intestine directly into portal blood and does not require packaging in chylomicrons for transport into intestine lymph.

Peripheral lymph flow in sheep with bacterial peritonitis: evidence for increased peripheral microvascular permeability accompanying systemic sepsis

We studied the effects of systemic sepsis on peripheral microcirculatory fluid exchange by examining changes in flow (Qlymph) and lymph-to-plasma [L/P] total protein and albumin ratios from lymph draining, the efferent duct of a prefemoral lymph node in sheep, before and during surgically-induced peritonitis. After baseline study, peritonitis was produced by cecal ligation, perforation, and devascularization. By 24 hours blood cultures revealed a polymicrobial bacteremia. The hemodynamic response to the septic insult during the 72-hour study period was characterized by an increase in heart rate and an initial fall in stroke volume index; yet, the mean blood pressure remained unchanged from baseline levels throughout the study protocol. The intrapulmonary shunt fraction increased (p less than 0.05) by 48 hours, as did both the Qlymph (2.6 +/- 1.9 ml/hr to 6.8 +/- 4.6 ml/hr; p less than 0.05) and the calculated lymph albumin clearance (1.6 +/- 1.2 ml/hr to 3.1 +/- 1.7 ml/hr; p less than 0.05). Although the calculated serum to interstitial colloid osmotic pressure gradient fell (F = 4.37; p less than 0.04), both the [L/P] total protein and albumin ratios were unchanged from baseline throughout 72 hours of study. Further, [L/P] total protein ratios were unrelated to Qlymph (r = -0.20); as Qlymph (experimental/baseline) increased with sepsis, [L/P] total protein ratio (experimental/baseline) did not fall (r = +0.62). We therefore conclude that systemic sepsis, as represented by this model of bacterial peritonitis, results in increased peripheral microcirculatory fluid flux that is primarily a consequence of an increase in permeability of the peripheral microvascular exchanging membrane.

[Studies on the biotransformation and anti-ulcer effects of 2-(nicotinoylaminoethanesulfonylamino)pyridine]

Investigations were made of 2-(nicotinoylaminoethanesulfonylamino)pyridine (NTP), a new compound with anti-ulcer effects, to clarify the relationship between its biotransformation and pharmacological effects. The effect of NTP was investigated by using two types of experimental gastric ulcer models in rats. The anti-ulcer effect was revealed to be an action of NTP itself. In order to study the biotransformation of NTP, a quantitative analysis method by HPLC was established. When NTP was orally administered to rabbits, 2-(aminoethanesulfonylamino)pyridine (TP), which is a metabolite of NTP, appeared in plasma and lymph. When NTP was orally administered to rabbits to investigate its distribution in organs, a massive amount of NTP and TP appeared in various organs within 7 hr after administration. We conclude that the pharmacological effect of NTP appears to be associated mainly with the unchanged substance.

[Pharmacokinetic and pharmacological studies on cetraxate, an anti-ulcer agent]

Cetraxate hydrochloride was administered either orally or intravenously to rabbits, and its concentration in body fluids was determined by using the HPLC method. Cetraxate was easily hydrolyzed in the gastrointestinal tract and blood, and it was metabolized to p-hydroxyphenylpropionic acid (PHPA) and a new metabolite, p-hydroxybenzoic acid (PHBA). After oral administration of cetraxate hydrochloride, a large amount of unchanged drug was distributed to the gastric wall. PHPA was distributed in all the organs examined, excluding the brain. To determine whether or not the anti-ulcer action of cetraxate hydrochloride was due to the unchanged drug, PHPA, or tranexamic acid, studies with aspirin and water-immersion -induced gastric ulcers in rats were performed. As a result, it was found that tranexamic acid had an anti-ulcer action similar to that of cetraxate hydrochloride.

Effect of endotoxemia on hypoxic pulmonary vasoconstriction in unanesthetized sheep

This study examined the effect of acute endotoxemia on hypoxic pulmonary vasoconstriction (HPV) in awake sheep. Thirteen sheep were chronically instrumented with Silastic catheters in the pulmonary artery, left atrium, jugular vein, and carotid artery; with a Swan-Ganz catheter in the main pulmonary artery; with a chronic lung lymph fistula; and with a tracheostomy. Base-line HPV was determined by measuring the change in pulmonary vascular resistance (PVR) while sheep breathed 12% O2 for 7 min. Concentrations of immunoreactive 6-keto-PGF1 alpha and thromboxane B2 (TXB2) were measured in lung lymph during the hypoxic challenge. Escherichia coli endotoxin (0.2-0.5 micrograms/kg) was infused intravenously. Four hours after endotoxemia, HPV was measured. In five sheep, meclofenamate was infused at 4.5 h after endotoxemia and HPV measured again. During the base-line hypoxic challenge, PVR increased by 36 +/- 9% (mean +/- SE). There was no significant change in lung lymph 6-keto-PGF1 alpha or TXB2 levels with hypoxia. Twelve of the 13 sheep showed a decrease in HPV 4 h after endotoxemia; the mean change in PVR with hypoxia was -8 +/- 5%, which was significantly (P less than 0.05) reduced compared with base-line HPV. The infusion of meclofenamate at 4.5 h after endotoxin did not restore HPV.

Potentiation of lung vascular response to endotoxin by superoxide dismutase

We studied the effects of superoxide dismutase (SOD), an enzyme that converts superoxide into peroxide, on the cardiopulmonary response to endotoxin in sheep. Sheep (n = 18) were prepared for chronic measurement of cardiopulmonary variables, including lung lymph flow, by surgically implanting catheters under halothane anesthesia. Nine of the animals were studied before and after the administration of endotoxin (0.75 microgram/kg) with and without SOD. An additional nine animals received SOD without the lipopolysaccharide. Endotoxin produced an increase in lung lymph flow that was initially associated with a marked pulmonary arterial (PA) hypertension and reduced lymph-to-plasma protein ratio (L/P). The lymph flow remained elevated later in the response, but there was only a mild increase in PA pressure, and the L/P was normal. There was also a fall in blood neutrophils and in cardiac index. SOD increased this secondary elevation in lung lymph flow, and the corresponding L/P was greater than the preendotoxin value. The fall in neutrophil count, cardiac output, and the elevation in PA pressure seen with endotoxin were not affected by SOD. When administered in the absence of endotoxin, SOD produced no perceptible change in the cardiopulmonary and lymph values. We conclude that peroxide, hydroxyl ion, and/or other free radicals formed by the action of SOD must be responsible for a portion of the endotoxin response rather than superoxide itself.

Cholesterol absorption and turnover in hypercholesterolemic dogs

Cholesterol absorption was measured in chronically hypercholesterolemic dogs by four methods: the fecal recovery method of Borgström (1969, J. Lipid Res. 10: 331-337), the dual isotope method of Zilversmit and Hughes (1974, J. Lipid Res. 15: 465-473), the recovery of cholesterol in thoracic duct lymph collected continuously for 16 hr after a meal, and the recovery of isotopic cholesterol from the liver and plasma 24 hr after the animals consumed an isotope-containing meal. The four methods showed excellent agreement and indicated that dogs fed a cholesterol-rich synthetic diet absorb 5.2 +/- 0.5 g (mean +/- SD) of cholesterol per day and that cholesterol absorption is reasonably constant from week to week in these animals. Separate estimates of cholesterol excretion indicated that these dogs excreted 4.7 +/- 0.5 g of cholesterol per day, and thus were at or near the steady-state with regard to cholesterol input-output. These data, taken together with a previous report (1981, J. Lipid Res. 22: 598-609), indicate that the canine liver can clear up to 300 mg of chylomicron cholesterol/hr, and support the concept that chylomicron remnants do not contribute significantly to the hypercholesterolemia in these animals.

Effects of dopamine and vasopressin on histamine-induced increases in macromolecular permeability in the canine forelimb

Local intra-arterial infusions of histamine, 16 micrograms base/min, for 60 minutes produced increases in lymph flow, lymph total protein concentration, the lymph/plasma total protein ratio, and weight in canine forelimbs perfused at constant flow. The weight gains were far greater than can be accounted for by an increase in vascular volume, and must, therefore, be attributed to edema formation. Treatment with dopamine (2, 4, or 8 micrograms base/min) or arginine vasopressin (AVP) initially produced an increase in perfusion pressure reflecting constriction of the forelimb vasculature. AVP prevented the histamine-induced increase in lymph flow, lymph total protein concentration, the L/P total protein ratio, and weight gain. In contrast, treatment with DA at three different dose levels failed to affect the histamine response. The increases in lymph flow, lymph total protein concentration, lymph/plasma total protein ratio, and weight were comparable to that produced by histamine in the absence of DA. These data fail to provide evidence for DA mediated regulation of macromolecular permeability, and suggest that endothelial cells either do not contain DA receptors, or that their activation does not affect macromolecular permeability.

Surfactants identified in lung lymph and their ability to act as abhesives

Phospholipid has been extracted from pulmonary lymph collected from 10 dogs. Thin-layer chromatography was used to identify phosphatidylcholine (PC) 55.6 +/- 2.9%, sphingomyelin 21.3 +/- 1.7%, phosphatidylethanolamine 11.2 +/- 4.9%, and lysophosphatidylcholine 5.9 +/- 0.8%. All extracts proved highly surface active, reducing the surface tension of saline to 27.7 +/- 0.7 dyn/cm upon 80% film compression and increasing the maximum contact angle on glass (theta) from 7 +/- 1 to 47.4 +/- 1.4 degrees. The hydrophobic properties induced on glass were further demonstrated by the ability to cause saline to withdraw and expose a dry surface. A standard adhesion test was used to measure the "tack" produced by the major proteins in lymph. However, when the surface energy of the hydrophilic glass surfaces was reduced by a monolayer of lymph phospholipid extract or an equivalent mixture of synthetic surfactants, the adhesive force was reduced by 79 +/- 4% for albumin and 55 +/- 4% for globulin. As a 0.1% liposomal suspension, PC gave 55% release with albumin. Reversible bonding of the lumen of lymph vessels by the "tacky" proteins present is discussed as a possible factor contributing to the large changes in flow resistance known to occur in the pulmonary lymphatic system.

Pulmonary dysfunction secondary to soft-tissue endotoxin

Our purpose was to determine whether peripheral soft tissues produce and release prostanoids in response to local sepsis, and whether this mediator release can produce pulmonary dysfunction. Escherichia coli endotoxin (2 micrograms/kg in 100 mL of saline) was injected below the hide of the flank in seven unanesthetized sheep. In three additional sheep, ibuprofen (12.5 mg/kg of body weight) was injected with the endotoxin. Thromboxane B2 and 6-keto-PGF1 alpha (prostacyclin) levels were measured in tissue lymph draining the flank, lung lymph, pulmonary artery (Ppa), and aortic plasma. One hour after endotoxin administration, mean PaO2 decreased from 90 to 74 mm Hg and Ppa increased from 22 to 35 mm Hg. Lung lymph flow (QL) increased only 50% with QL being protein poor. No increase in lung or peripheral soft-tissue vascular permeability was noted. Tissue lymph (TxB2) increased from 220 +/- 114 to greater than 10,000 pg/mL with levels in Ppa plasma increasing from 300 +/- 128 to 595 +/- 124 pg/mL and aortic plasma from 270 +/- 141 to 410 +/- 104 pg/mL. Lung lymph TxB2 paralleled aortic values. Peak levels of 6-keto-PGF1 alpha in systemic lymph exceeded 2,000 pg/mL while levels in lung lymph remained relatively constant. The pulmonary injury and the increase in TxB2 was prevented by ibuprofen. We conclude that the response of soft tissue to local endotoxin is to release thromboxane in quantities sufficient to raise plasma levels and to produce hypoxia and pulmonary hypertension. The lung dysfunction is not produced by an increase in lung water or vascular permeability.

Distribution of apolipoproteins A-I and B among intestinal lipoproteins

Chylomicrons and very low density lipoproteins (VLDL) are produced by the intestine and these nascent particles are thought to be similar to their counterparts in intestinal lymph. To study the relationship between these lipoproteins within the cell and those secreted into the lamina propria and lymph, we have isolated enterocytes, lamina propria, and mesenteric lymph from rats while fasted and after corn oil feeding. Apolipoprotein A-I and B content were measured by radioimmunoassay in cell, lamina propria, and lymph fractions separated by Sepharose 6B and 10% agarose chromatography, and by KBr isopycnic density centrifugation. ApoA-I in the cell and the underlying lamina propria was found partly in those fractions in which chylomicron and very low density lipoproteins (chylo-VLDL) and high density lipoproteins (HDL) elute, but more abundantly where unassociated 125I-labeled apoA-I was eluted. In the lymph, however, 74% of apoA-I eluted in the HDL region and no peak of free apoA-I was found. ApoB and apoC-III within the enterocyte were found distributed in the position of particles eluting not only with chylomicrons and VLDL, but also in the regions corresponding to LDL and HDL. In the lamina propria and lymph, on the other hand, most of the apoB was found in the region of VLDL and chylomicrons. These results indicate that the patterns in lymph lipoproteins and the lamina propria do not exactly mirror the distribution of apoA-I and B among lipoproteins inside the cell. This may be because intracellular apoproteins may be unassociated with lipoproteins, or they could be associated with lipoproteins in various stages of assembly of protein with lipids. Furthermore, the apoprotein composition of intestinal lipoproteins is altered after secretion from the enterocyte. Finally, not all apoproteins seem to be secreted in association with identifiable lipoprotein particles from the enterocyte.

Lymph, pancreatic and gastrointestinal hormones in response to feeding in the conscious pig

Concentrations of several gastrointestinal hormonal peptides were measured in lymph from the cisterna chyli and in arterial plasma; in healthy, conscious pigs during ingestion of a meal. Lymph concentrations of the pancreatic hormones insulin, glucagon and pancreatic polypeptide were small compared with plasma concentrations, although postprandial increments were significant. In contrast lymph concentrations of gastrin, cholecystokinin, motilin and gastric inhibitory peptide (GIP) from the foregut showed a more marked postprandial rise than the pancreatic hormones. Indeed the total integrated responses of these peptides in lymph reached about 50% of those seen in arterial plasma. It would appear unlikely that the lymphatics constitute an important transport mechanisms for these regulatory peptides. However, lymph concentrations of hormones may reflect levels in interstitial fluid better than plasma and may be of value in assessing putative physiological actions within a target tissue.

Collateral arterial formation. Lymph draining ischemic kidneys contains a neovascular stimulating agent of high molecular weight

An agent has been identified in lymph from rat kidneys rendered ischemic by partial renal artery occlusion that induces a striking neovascular response in a hamster cheek-pouch assay system. The factor has a high molecular weight, cannot be identified in lymph from normal kidneys, and is associated with a marked increase in vascularity and in endothelial cell turnover in the cheek pouch employed for assay. This factor may play an important role in the production of the collateral arterial circulation found in the presence of renal artery stenosis and renal ischemia.

[Amino acid composition of the lymph and blood in allergic transformations of the body]

The time-course of changes in the content of free amino acids and total protein in lymph of the thoracic duct and peripheral blood was studied in dogs during sensitization and anaphylactic shock (AS). Allergic rearrangement of the body during AS was accompanied by considerable disorders in redistribution of free amino acids in body fluids (blood, interstitial fluid and lymph). It is assumed that changes in the quantitative ratios occurring between individual amino acids during metabolic processes under sensitization are likely to cause protein biosynthesis disorders in the body experiencing allergic rearrangement.