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Contribution of lymphatic drainage through stomata to albumin removal from pleural space
No full textThe contribution of lymphatic drainage through the stomata of parietal mesothelium to the overall removal of labeled albumin from the pleural space was found 89% in sheep with very large hydrothoraces (10 ml/kg), a condition involving a approximately 20 times increase in lymphatic drainage [Broaddus et al., J. Appl. Physiol. 64 (1988) 384]. We determined this contribution in anesthetized rabbits with small (0.12 ml/kg) and large (2.4 ml/kg) hydrothoraces of Ringer-albumin with labeled albumin and labeled dextran-2000 kDa. This dextran was used as marker of liquid removal through the stomata because it should essentially leave the pleural space through the stomata only, owing to its size. The removal of labeled albumin by lymphatic drainage through the stomata was 39% of the overall removal in the small hydrothoraces, and 64% in the large ones. Hence, lymphatic drainage through the stomata does not contribute most of protein and liquid removal from the pleural space under physiological conditions, as it has been maintained. It markedly increases with the increase in pleural liquid volume
Albumin transcytosis from the pleural space
No full textOccurrence of transcytosis in pleural mesothelium was verified by measuring removal of labeled macromolecules from pleural liquid in experiments without and with nocodazole. To this end, we injected 0.3 ml of Ringer-albumin with 750 microg of albumin-Texas red or with 600 microg of dextran 70-Texas red in the right pleural space of anesthetized rabbits, and after 3 h we measured pleural liquid volume, labeled macromolecule concentration, and, hence, labeled macromolecule quantity in the liquid of this space. Labeled albumin left was 318 +/- 28 microg in control and 419 +/- 17 microg in nocodazole experiments (means +/- SE); hence, whereas ventilation was similar its removal was greater (P < 0.01) in control experiments. Labeled dextran left was 283 +/- 10 microg in control and 381 +/- 21 microg in nocodazole experiments; hence, whereas ventilation was similar its removal was greater (P < 0.01) in control experiments. These findings indicate occurrence of transcytosis from the pleural space. Liquid removed by transcytosis was 0.05 ml/h. This amount times unlabeled albumin concentration under physiological conditions (10 mg/ml) times lumen-vesicle partition coefficient for albumin (0.78) provides fluid-phase albumin transcytosis: approximately 203 microg. h(-1) kg(-2/3). Transcytosis might contribute a relevant part of protein and liquid removal from the pleural spac
Macromolecule transfer through mesothelium and connective tissue
No full textDiffusional permeability (P) to inulin, albumin, and dextrans was determined in specimens of parietal pericardium of rabbits, which may be obtained with less damage than pleura. Pin, Palb, Pdx,70, Pdx,150, Pdx,550 and Pdx,2000 were (x 10-5 cm / s): 0.51 ± 0.06 (SE); 0.18 ± 0.03; 0.097 ± 0.021; 0. 047 ± 0.011; 0.025 ± 0.004 and 0.021 ± 0.005, respectively. Pin, Palb, and Pdx,70 of connective tissue, obtained after having removed mesothelium from specimens, were (x 10-5 cm / s): 10.3 ± 1.42; 2.97 ± 0.38 and 2.31 ± 0.16, respectively. Hence, Pin, Palb, and Pdx,70 of mesothelium were (x 10-5 cm / s): 0.54; 0.20 and 0.10, respectively. Inulin (like small solutes) fitted the relationship P - solute radius for restricted diffusion with 6 nm “pore” radius, whereas macromolecules were much above it. Hence, macromolecule transfer mainly occurs through “large pores” and / or transcytosis. In line with this, addition of phospholipids on luminal side (which decreases “pore” radius to 1.5 nm) halved Pin, but did not change Palb and Pdx,70. Pin is roughly similar in mesothelium and capillary endothelium, whereas P to macromolecules is greater in mesothelium. Albumin diffusion coefficient through connective tissue was 17 % of that in water. Mesothelium provides 92 % of resistance to albumin diffusion through pericardium
Labeled albumin in plasma and removal paths from pleural space in control and increased ventilation
No full textIncreased ventilation was shown to markedly increase lymphatic drainage and plasma content of labeled proteins injected into pleural space relative to control ventilation. These proteins reach plasma by lymphatic drainage: directly through parietal pleura stomata, and indirectly from pleural interstitium, reached by diffusion, convection and transcytosis. Increased drainage from interstitium should not involve a comparable increase in protein removal from pleural space by these transports, while increased drainage through stomata involves a comparable increase in protein removal. Hence, relative increase in labeled protein removal from pleural space caused by increased ventilation should be marked only if drainage through stomata contributed most of this removal, whereas relative increase of labeled proteins in plasma should be marked in either case. We injected 3 ml of albumin–Ringer with albumin–Texas red into the pleural space of three groups of anesthetized rabbits: control, CO2-, or muscle stimulation-increased ventilation. Increased ventilation for 3 h (78 and 61%, respectively) increased (P<0.01) labeled albumin in plasma by 132 and 106%, respectively, but did not significantly increase its removal. Hence, lymphatic drainage through stomata should not contribute most of liquid and protein removal from pleural space
Equivalent radius of paracellular “pores” of the mesothelium
No full textDiffusional permeability (P) to H2O, Cl- and mannitol was determined in specimens of rabbit parietal pericardium without and with phospholipids added on luminal side, as previously done with sucrose and Na+. P to above molecules and to Na+ was also determined after having scraped away mesothelium from specimens. Pw, PCl-, PNa+ and Pman of connective tissue were: (x 10-5 cm / s) 73.1 ± 7.3 (SE); 59.5 ± 4.5; 41.7 ± 3.4; 23.4 ± 2.4. From these and corresponding data on integer pericardium Pw, PCl-, PNa+ and Pman of mesothelium were computed. They were: (x 10-5 cm / s) 206; 17.9; 9.52; 3.93, and 90.2; 14.4; 4.34; 1.75, without and with phospholipids, respectively. As previously found for Psuc, P to solutes is smaller in mesothelium than in connective tissue, though the latter is about 35-fold thicker; instead, Pw is higher in mesothelium, suggesting marked water diffusion through cell membrane. Equivalent radius of paracellular “pores” of mesothelium was computed with 2 approaches, disregarding Pw. The former, a graphical analysis on P - molecular radius diagram, yielded 6.0 and 1.7 nm without and with phospholipids, respectively. The latter, based on Pman, Psuc and function for restricted diffusion, yielded 7.8 and 1.1 nm, respectively
Albumin transcytosis in mesothelium
No full textApparent permeability to albumin (P(alb)) was measured with (125)I-albumin in specimens of rabbit parietal pericardium from lumen to interstitium (L-I) and from interstitium to lumen (I-L). With albumin concentration (C(alb)) 0.5%, P(alb) (x 10(-5) cm/s) L-I at 37 degrees C was 0.172 +/- 0.019 SE; it decreased to 0.092 +/- 0.022 I-L at 37 degrees C, 0.089 +/- 0.021 L-I at 12 degrees C, and 0.084 +/- 0.018 I-L at 12 degrees C. These findings provide evidence for an active transport L-I, likely transcytosis. With C(alb) 2.5%, 0.05%, and 0.005%, P(alb) L-I at 37 degrees C was 0.188 +/- 0.023, 0.156 +/- 0.021, and 0.090 +/- 0.021, respectively; at 12 degrees C it was 0.089 +/- 0.017, 0.083 +/- 0.019, and 0.087 +/- 0.026, respectively. Hence, active albumin transport ceases with C(alb) 0.005%; P(alb) values I-L at 12 degrees C and with C(alb) 0.005% are similar and provide diffusional permeability. With physiological C(alb) (approximately 1%), active albumin flux was approximately 5 x 10(-4) micromol x h(-1) x cm(-2). Apparent permeability to FITC-dextran 70 (P(dx)) was also measured. P(dx) (x 10(-5) cm/s) L-I at 37 degrees C with C(alb) 0.5% was 0.095 +/- 0.018; it decreased to 0.026 +/- 0.004 I-L (37 degrees C, C(alb) 0.5%), 0.038 +/- 0.007 at 12 degrees C (L-I, C(alb) 0.5%), 0.030 +/- 0.009 with C(alb) 0.005% (L-I, 37 degrees C), and 0.032 +/- 0.011 with nocodazole (L-I, 37 degrees C, C(alb) 0.5%). These findings provide evidence for transcytosis and confirm conclusions drawn from P(alb). Vesicular liquid flow, computed from vesicular dextran flux (fluid-phase only), was approximately 3.5 microl x h(-1) x cm(-2). Transcytosis seems a relevant mechanism, removing protein and liquid from serous cavities
Pleural mesothelium lubrication after hyaluronidase, neuraminidase or pronase treatment
No full textCoefficient of kinetic friction (μ) of pleural mesothelium has been found to increase markedly after mesothelial blotting and rewetting. This increase disappeared after addition of a solution with hyaluronan or sialomucin, though previous morphological studies showed that only sialomucin occurs in mesothelial glycocalyx. In this research we investigated whether μ of rabbit pleural mesothelium increased after hyaluronidase, neuraminidase or pronase treatment. Hyaluronidase and neuraminidase did not increase μ, though neuraminidase cleaved sialic acid from mesothelial glycocalyx of diaphragm specimens, and removed hystochemical stain of sialic acid from glycocalyx. Sialomucin treated with neuraminidase lowered μ of blotted mesothelium, though less than untreated sialomucin; this feature plus lubrication provided by other molecules could explain why μ did not increase after neuraminidase. Short pronase treatment (in order to affect only glycocalyx proteins) increased μ; this increase was removed by hyaluronan or sialomucin. After pronase treatment μ decreased with increase in sliding velocity, indicating a regime of mixed lubrication, as in blotted mesotheliu
Fisiologia umana
No full textLa quindicesima edizione di Fisiologia Umana continua la tradizione delle precedenti, presentando la fisiologia umana in modo ancora più attuale, leggibile e orientato agli studenti. La veste grafica è stata completamente rifatta, per rendere tutte le figure più accurate, chiare, vivaci e leggibili. Basta una sola occhiata per apprezzare la bellezza dell’iconografia. Un elemento pedagogico aggiunto è un riquadro che appare in molte figure e che serve ad aiutare gli studenti a meglio integrare i processi cellulari e molecolari con le loro posizioni negli organi del corpo. La terminologia è stata aggiornata per essere coerente con quella utilizzata dai professionisti del settore e per essere conforme a Terminologia Anatomica, Terminologia Istologica, Terminologia Embriologica, Nomenclatura di Chimica Organica IUPAC e Nomenclatura dei Principi Chimici IUPAC. Tutti capitoli sono stati aggiornati per essere in linea con le ultime ricerche e sono presentati in modo ampio e approfondito, adatto allo studente universitario di fisiologia umana
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