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In this report, we present a rapid method for producing high-quality micrographs suitable for determining the size distributions of particles in concentrated samples of postprandial chylomicrons and chylomicron remnants. The procedure consists of mixing particles with osmium tetroxide in water to stabilize the lipids of the particles. These fixed and positively stained particles are then negatively stained with phosphotungstate in the presence of dilute sucrose. This dual staining procedure prevents the fusion and clustering of chylomicrons during processing for electron microscopy and is effective with particles of different lipid compositions. In addition, this procedure is simple and rapid, adding only one mixing step and 5 min to the preparation time required for conventional negative stains.

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Studies have been made on the content of catecholamines (norepinephrine, adrenaline, dihydroxyphenylalanine) in the wall of the thoracic lymphatic duct of puppies during their first 3 months of postnatal life. It was found that within this period, the content of norepinephrine increases, that of adrenaline remains unchanged, whereas dihydroxyphenylalanine is detected only in animals of the first month. The increase in norepinephrine content indicates gradual maturation of the adrenergic innervation in the wall of the lymphatic duct.

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The importance of antibodies to cholera toxin (CT) versus desensitization of intestinal adenylate cyclase for protection against experimental cholera in the rat was investigated. Animals were immunized five times with CT either perorally or intravenously; antitoxic antibodies were measured in both serum and bile, and intestinal anti-CT-containing plasma cells (ACC) as well as eosinophilic leucocytes were counted. Both peroral and intravenous immunizations induced high levels of serum antibodies, while antibodies in bile appeared only after peroral immunization. The number of eosinophilic leucocytes in the intestinal mucosa increased in response to peroral immunization. CT-induced stimulation of intestinal adenylate cyclase was significantly suppressed, i.e., desensitized, after peroral immunization, but was equally stimulated in intravenous immunized and in control animals. A constant and long-lasting protection against CT-induced secretion was obtained after peroral immunization. This protection correlated neither to the concentrations of antitoxic antibodies in serum, nor to those in bile, nor to the number of ACC, but did correlate to the desensitization of adenylate cyclase.

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The composition of lymph draining the sheep caudal mediastinal lymph node is believed to reflect the composition of lung interstitial fluid. Although long-term lymph fistulas have been extensively utilized in studies related to lung microvascular fluid and protein flux, attention has thus far not been focused on lipoproteins as they might appear in lung interstitial space. We therefore characterized the lipoprotein distributions and measured triglyceride and cholesterol concentrations of lung lymph and plasma in nine unanesthetized sheep with long-term embedded instrumentation. We also measured triglyceride and cholesterol concentrations in prefemoral and thoracic duct lymph. The plasma LDL concentration was 55.3 +/- 20.2 mg/dl and HDL concentration was 99.9 +/- 27.2 mg/dl. By comparison, the lung lymph LDL concentration was 27.7 +/- 3.0 mg/dl and the HDL concentration was 45.4 +/- 11 mg/dl. The major sheep lipoprotein classes (LDL, HDL), although low in concentration compared to humans, are present in lung lymph in relative proportions similar to those of plasma. Analytical ultracentrifugation revealed the presence of a fast-floating component in lung lymph HDL that was not present in plasma. Electron microscopy showed two sizes of particles in lung lymph HDL, 135A and 97A, which probably correspond to the fast-floating and slow-floating components, respectively; plasma HDL contained only 94 A particles. Changes in the physical properties of HDL present in lung lymph suggest modification of the HDL either in the endothelial barrier or interstitial fluid of the lung.

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Only little is known about the activity of the fibrinolytic factors outside the vascular space. Therefore fibrinolytic activity was measured in blood and thoracic duct lymph of dogs. The results are summarised as follows: With regards to the fibrinolytic rates, the extravascular spaces take on a special position: There is a profibrinolytical total constellation.

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The sites of origin of renal lymph were studied by analysis of simultaneously collected samples of lymph and plasma. The samples included renal hilar (HL) and capsular lymph (CL), thoracic duct lymph (TD), renal venous (RVP) and arterial plasma (AP), and were analyzed for Na+, Cl-, K+, urea, glucose, inulin, and PAH concentrations. The glucose concentrations of HL (76 mg/100 ml, SE +/- 1.9), and CL (92 mg/100 ml, SE +/- 2.5) were significantly different (P less than 0.01) from that of RVP (86 mg/100 ml, SE +/- 2.2). Concentrations of both inulin and PAH in CL and HL fell between the AP and RVP values. The concentration of inulin in CL (CL/RVP = 1.27) exceeded that in HL (HL/RVP = 1.10), but no such difference was detected for PAH. The Na+ (152 meq/liter) and Cl- (129 meq/liter) concentrations in HL were significantly (P less than 0.01) higher than those in CL (Na+ = 148 meq/liter; Cl- = 120 meq/liter), in TD (Na+ = 146 meq/liter; Cl- = 121 meq/liter), and in RVP (Na+ = 144 meq/liter; Cl- = 114 meq/liter. These differences remained highly significant when the electrolyte concentrations were converted to milliequivalents per kilogram H2O. In contrast, no significant differences were detected between the concentrations of urea in the various fluids sampled. It is concluded that CL and HL do not drain a perfectly homogeneous intrarenal pool, and that they do not equilibrate with RVP or AP within the kidney. The results also indicate that CL and HL derive a small component from tubular reabsorbate; that for CL stemming from the cortex, and that for HL from the deeper cortex and outer medulla.

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