Histamine-induced pulmonary edema distal to pulmonary arterial occlusion

Histological studies provide evidence that the bronchial veins are a site of leakage in histamine-induced pulmonary edema, but the physiological importance of this finding is not known. To determine if a lung perfused by only the bronchial arteries could develop pulmonary edema, we infused histamine for 2 h in anesthetized sheep with no pulmonary arterial blood flow to the right lung. In control sheep the postmortem extravascular lung water volume (EVLW) in both the right (occluded) and left (perfused) lung was 3.7 +/- 0.4 ml X g dry lung wt-1. Following histamine infusion, EVLW increased to 4.4 +/- 0.7 ml X g dry lung wt-1 in the right (occluded) lung (P less than 0.01) and to 5.3 +/- 1.0 ml X g dry wt-1 in the left (perfused) lung (P less than 0.01). Biopsies from the right (occluded) lungs scored for the presence of edema showed a significantly higher score in the lungs that received histamine (P less than 0.02). Some leakage from the pulmonary circulation of the right lung, perfused via anastomoses from the bronchial circulation, cannot be excluded but should be modest considering the low pressures in the pulmonary circulation following occlusion of the right pulmonary artery. These data show that perfusion via the pulmonary arteries is not a requirement for the production of histamine-induced pulmonary edema.     

Effects of the removal of adherent and phagocytic cells on the spleen cell lymphoproliferative response of tumor-bearing mice

Summary Cell-mediated immunity was investigated in two BALB/c mouse tumor systems using the lymphoblastogenesis test with phytohemagglutinin as the mitogen. This lymphoproliferative response was quantitated using the Stimulation Index (SI). There was little evidence for suppressor cell activity in cell mixing experiments in which spleen cells from #51 cell-injected mice were mixed with spleen cells from normal mice. Following macrophage removal by Sephadex G-10 columns and carbonyl iron ingestion, there were no significant changes in the SI values for spleen cells from the #51 cell-injected mice. In contrast, spleen cells from mice injected with H238 cells, a herpes virus-transformed cell line, had a significantly lower SI value than that of normal mice. Suppressor cell activity was demonstrated in cell mixing experiments in which spleen cells from H238 cell-injected mice were mixed with normal spleen cells. Removal of adherent cells from spleen cells from H238 cell-injected mice by Sephadex G-10 columns restored the SI value to that of normal mice. An increased SI value was also seen after removal of phagocytic cells by carbonyl iron. These results suggested that cells with the functional properties of macrophages played an important part in the immunosuppression observed in the H238 tumor system. Comparison of the two macrophage depletion methods suggested that another cell population was also involved in the suppressive effect. Results of immunofluorescent techniques with anti-Lyt-1 and anti-Lyt-2 monoclonal antibodies show these cells to be Ly 1^–, Ly 2,3⁺ phenotypes of T-lymphocytes.     

Saturation transfer EPR spectroscopy on spin-labeled muscle fibers using a loop-gap resonator.

Previously, saturation transfer (ST-EPR) studies of biomolecular dynamics have involved the use of a resonant cavity and the V'2 display (absorption, second harmonic, out of phase). In the present study, we replaced the resonant cavity with a loop-gap resonator and used the U'1 display (dispersion, first harmonic, out of phase) to study spin-labeled muscle fibers. The new resonator and display showed several advantages over those previously used. It produced virtually noiseless U'1 spectra on a 0.4 microliter sample using a 4 min scan; previous U'1 experiments on spin-labeled muscle, using a conventional rectangular cavity, resulted in an unacceptably low signal-to-noise ratio. The high filling factor of the resonator facilitated the study of these extremely small fiber bundles and permitted high microwave field intensities to be achieved at much lower incident microwave power levels, thus greatly enhancing the signal-to-noise ratio in U'1 experiments. This reduction in the noise level made it possible to benefit from the other advantages of U'1 over V'2, such as stronger signals, simpler line shapes, and simpler data analysis. For these muscle fiber samples, the resulting sensitivity (signal/noise/sample volume) of the U'1 signals was greater than 100 times that of V'2 signals obtained in a conventional cavity. Another advantage of the U'1 display is that signals from weakly immobilized probes, i.e., probes that have nanosecond rotational mobility relative to the labeled protein (myosin), are greatly suppressed relative to strongly immobilized probes. This reduces the ambiguity of spectral analysis, and eliminates the need for chemical treatments [e.g., using K3Fe(CN)6] that were previously required in muscle fibers and other systems. Further suppression of this weakly immobilized component was achieved in U'1 spectra by increasing the microwave power and decreasing the field modulation frequency.     

Effect of Na+, K+, ouabain,amiloride and ethacrynic acid on the transepithelial potential across Malpighian tubules of Locusta

A transepithelial potential of +8.74±0.29 mV (n = 85) has been recorded across the Malpighian tubules of Locusta. The effect of varying the Na⁺ and K⁺ concentration in the bathing medium on the transepithelial potential has been determined. The data show that the transepithelial potential does not obey the Nernst equation for K⁺. Ouabain, ethacrynic acid and amiloride all inhibit the transepithelial potential. The results are discussed in relation to the nature of the mechanisms of cation transport across the Malpighian tubules.     

Absence of adrenergic red cell pH and oxygen content regulation in American eel (Anguilla rostrata) during hypercapnic acidosis in vivo and in vitro

Summary American eels (Anguilla rostrata) were exposed to acute (30 min) external hypercapnia (1% CO₂ or 5% CO₂ in air) in order to assess the involvement of circulating catecholamines in regulating red blood cell (RBC) pH and oxygen content during whole blood acidosis. Plasma adrenaline levels increased approximately 5-fold during severe hypercapnia yet absolute levels remained below 1.0 nM; plasma noradrenaline levels were unchanged. Both RBC pH and oxygen bound to haemoglobin ([O₂]/[Hb]) conformed to in vitro relationships with whole blood pH (pHe) indicating absence of regulation during hypercapnia in vivo. Pre-treatment of eels with - or -adrenoceptor antagonists, phentolamine or propranolol was without effect on RBC pH or [O₂]/[Hb] during hypercapnia. Further, intra-arterial injection of adrenaline (final plasma concentration=134 nM) or noradrenaline (final plasma concentration = 34 nM) into hypercapnic eels 5 min prior to blood sampling did not modify any measured blood variable RBC nucleoside triphosphate (NTP) levels, RBC pH and [O₂]/[Hb]. In vitro, the application of adrenaline or noradrenaline to eel RBC's during graded normoxic hypercapnia or hypoxic hypercapnia (noradrenaline only) did not affect RBC pH significantly. RBC NTP levels were depressed by noradrenaline in vitro but only during hypoxic hypercapnia.The results demonstrate adrenergic insensitivity of eel RBC's in vivo even under conditions (acidosis, hypoxemia) known to enhance catecholamine-mediated RBC responses in other species. We conclude that the American eel has no capacity to regulate RBC pH during hypercapnia and consequently [O₂]/[Hb] is reduced in accordance with the in vitro Root effect.     

Altered function of pulmonary surfactant in fatty acid lung injury

To determine whether acute fatty acid lung injury impairs pulmonary surfactant function, we studied anesthetized ventilated rabbits given oleic acid (55 mg/kg iv, n = 11) or an equivalent volume of saline (n = 8). Measurements of pulmonary mechanics indicated a decrease in dynamic compliance within 5 min of injury and a decrease in lung volume that was disproportionately large at low pressures, consistent with diminished surfactant activity in vivo. Bronchoalveolar lavage fluid obtained 1 h after injury had significantly increased erythrocytes and total leukocytes, largely polymorphonuclear cells. The phospholipid content and composition of the cell-free fraction had only minor changes from those of controls, but the protein content was increased 35-fold. Measurements of lavage surface activity in vitro showed an increase in average minimum surface tension from 1.3 +/- 0.4 (SE) dyn/cm in controls to 20.2 +/- 3.9 dyn/cm in injured animals. The alterations in static pressure-volume curves and decrease in lavage surface activity suggest a severe alteration of surfactant function in this form of lung injury that occurs despite the presence of normal amounts of surfactant phospholipids.     

Age and hypohydration independently influence the peripheral vascular response to heat stress

Seven young (Y, 22-28 yr) and seven middle-aged (MA, 49-60 yr) normotensive men of similar body size, fatness, and maximal oxygen uptake (VO2max) were exposed to a heat challenge in an environmental chamber (48 degrees C, 15% relative humidity). Tests were performed in two hydration states: hydrated (H, 25 ml water/kg body wt 1 h before the test, 2.5 h before exercise) and hypohydrated (Hypo, after 18-20 h of water deprivation). Each test began with a 90-min rest period during which the transiently increased plasma volume and decreased osmolality after drinking in the H condition returned to base line. This period was followed by 30 min of cycle exercise at a mean intensity of 43% VO2max and a 60-min resting recovery period with water ad libitum. Although prior drinking caused no sustained changes in plasma osmolality, Hypo increased plasma osmolality by 7-10 mosmol/kg in both groups. There were no significant age differences in water intake, urine output or osmolality, overall change in body weight, or sweating rate. In the H state, the percent change in plasma volume was less (P less than 0.01) during exercise for the Y group (-5.9 +/- 0.7%) than for the MA group (-9.4 +/- 0.6%). Esophageal temperature (Tes) was higher in the Hypo condition for both groups with no age-related differences. Throughout the 3-h period, mean skin temperature was higher in the Y group and significantly so (P less than 0.05) in the Hypo condition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anonymous nuclear DNA markers in the American oyster and their implications for the heterozygote deficiency phenomenon in marine bivalves

A puzzling population-genetic phenomenon widely reported in allozyme surveys of marine bivalves is the occurrence of heterozygote deficits relative to Hardy-Weinberg expectations. Possible explanations for this pattern are categorized with respect to whether the effects should be confined to protein-level assays or are genomically pervasive and expected to be registered in both protein- and DNA-level assays. Anonymous nuclear DNA markers from the American oyster were employed to reexamine the phenomenon. In assays based on the polymerase chain reaction (PCR), two DNA-level processes were encountered that can lead to artifactual genotypic scorings: (a) differential amplification of alleles at a target locus and (b) amplification from multiple paralogous loci. We describe symptoms of these complications and prescribe methods that should generally help to ameliorate them. When artifactual scorings at two anonymous DNA loci in the American oyster were corrected, Hardy-Weinberg deviations registered in preliminary population assays decreased to nonsignificant values. Implications of these findings for the heterozygote-deficit phenomenon in marine bivalves, and for the general development and use of PCR-based assays, are discussed.