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Pumping Activity (pumping + activity)
Selected AbstractsNew method for evaluation of lung lymph flow rate with intact lymphatics in anaesthetized sheepACTA PHYSIOLOGICA, Issue 2 2006T. Naito Abstract Aim:, Lung lymph has commonly been studied using a lymph fistula created by tube cannulation into the efferent duct of the caudal mediastinal node in sheep. In this method, the tail region of the caudal mediastinal node is resected and the diaphragm is cauterized to exclude systemic lymph contamination, and cannulation is performed into one of the multiple efferent ducts originating from the caudal mediastinal node. Moreover, the pumping activity of lymphatics might be diminished by cannulation. Therefore, the purpose of the study was to evaluate the flow rate of lung lymph with maintenance of intact lymphatic networks around the caudal mediastinal node to the thoracic duct in sheep. Methods:, An ultrasound transit-time flow meter was used to measure lung lymph flow. The thoracic duct was clamped just above the diaphragm and the flow probe was attached to the thoracic duct just after the last junction with an efferent duct from the caudal mediastinal node. The lung lymph flow rate was measured at baseline and under conditions of lung-oedema formation. Results:, The baseline lung lymph flow rate in our model was three- to sixfold greater than values obtained with the cannulation method. With oedema-formation, the lung lymph flow rate was the same as that measured using cannulation. Conclusion:, The lung lymph flow was unexpectedly large under the conditions of the study, and our data suggest that the drainage effect of lymphatics is significant as a safety factor against pulmonary oedema formation. [source] Poster Sessions CP07: Ions, Channels, Pumps and TransportersJOURNAL OF NEUROCHEMISTRY, Issue 2002A. A. Boldyrev Stationary level of reactive oxygen species (ROS) in cerebellum granule cells of 12-day-old-rats was measured using three fluorescent dyes characteristic of different location within the neuronal cell: BODIPY 581/591 (for LOO.radicals), DCF-DA (for H202) and DHR123 (OH-radicals in mitochondria). When the neurons were activated by N-methyl- d -aspartate (NMDA) a dose- and time-dependent rise of the fluorescent signal was registered with each of the three dyes; the former dye provided the smallest and the latter the largest response. 3-HPG, a ligand for metabotropic receptors decreases ROS fluorescence and suppressed the NMDA-induced effect. NMDA and kainic acid presented simultaneously cumulatively increased ROS levels. Ouabain, specific inhibitors of Na/K-pump induced a considerable increase in ROS fluorescence, which was decreased by 2.5,5 mm KCl, 50 mkM Vanadate or 10 mkM D-AP5, an inhibitor of NMDA-activated ionic channels. The K0.5 for activation of ROS generation by Ouabain was more than 250 mkM, which is much higher than that for inhibition of Na/K-ATPase or its rubidium pumping activity. The data show that the Na/K-pump protein regulates ROS production by NMDA-receptors and that the E1(Na) conformation of the Na/K-pump being less sensitive to ouabain may be responsible for the effects. The data illustrate functional interaction between ionotropic and metabotropic receptors and Na/K-ATPase. Acknowledgements:, Supported by DAAD, Grant 325-sm, Germany. [source] Decline in leaf growth under salt stress is due to an inhibition of H+ -pumping activity and increase in apoplastic pH of maize leavesJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 4 2009Britta Pitann Abstract In this study, salt-induced changes in the growth rate of maize (Zea mays L.) were investigated during the first phase of salt stress. Leaf growth was reduced in the presence of 100 mM NaCl, and effects were more pronounced for the salt-sensitive cv. Pioneer 3906 in comparison to the hybrid SR03. While hydrolytic activity of plasma membrane remained unaffected, H+ -pumping activity was reduced by 47% in Pioneer 3906, but was unchanged in SR03. Changes in apoplastic pH were detected by ratiometric fluorescence microscopy using the fluorescent dye fluorescein isothiocyanate-dextran (50 mM). Pioneer 3906 responded with an increase of 0.2 pH units in contrast to SR03 for which no apoplastic alkalization was found. With respect to the hypothesis that the apoplastic pH is influenced by salinity, it is suggested that salt resistance is partly achieved due to efficient H+ -ATPase proton pumping, which results in cell-wall acidification and loosening. [source] Protein,Protein Interaction of a Pharaonis Halorhodopsin Mutant Forming a Complex with Pharaonis Halobacterial Transducer Protein II Detected by Fourier-Transform Infrared Spectroscopy,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2008Yuji Furutani Pharaonis halorhodopsin (pHR) functions as a light-driven inward chloride ion pump in Natoronomonas pharaonis, while pharaonis phoborhodopsin (ppR; also called pharaonis sensory rhodopsin II, pSRII), is a light sensor for negative phototaxis. ppR forms a 2:2 complex with its cognate transducer protein (pHtrII) through intramembranous hydrogen bonds: Tyr199ppR,Asn74pHtrII and Thr189ppR,Glu43 pHtrII, Ser62pHtrII. It was reported that a pHR mutant (P240T/F250Y), which possesses the hydrogen-bonding sites, impairs its pumping activity upon complexation with pHtrII. In this study, effect of the complexation with pHtrII on the structural changes upon formation of the K, L1 and L2 intermediates of pHR was investigated by use of Fourier-transform infrared spectroscopy. The vibrational changes of Tyr250pHR and Asn74pHtrII were detected for the L1 and L2 intermediates, supporting that Tyr250pHR forms a hydrogen bond with Asn74pHtrII as similarly to Tyr199ppR. The conformational changes of the retinal chromophore were never affected by complexation with pHtrII, but amide-I vibrations were clearly different in the absence and presence of pHtrII. The molecular environment around Asp156pHR in helix D is also slightly affected. These additional structural changes are probably related to blocking of translocation of a chloride ion from the extracellular to the cytoplasmic side during the photocycle. [source] Adaptation of plasma membrane H+ -ATPase of rice roots to low pH as related to ammonium nutritionPLANT CELL & ENVIRONMENT, Issue 10 2009YIYONG ZHU ABSTRACT The preference of paddy rice for NH4+ rather than NO3 - is associated with its tolerance to low pH since a rhizosphere acidification occurs during NH4+ absorption. However, the adaptation of rice root to low pH has not been fully elucidated. This study investigated the acclimation of plasma membrane H+ -ATPase of rice root to low pH. Rice seedlings were grown either with NH4+ or NO3 - . For both nitrogen forms, the pH value of nutrient solutions was gradually adjusted to pH 6.5 or 3.0. After 4 d cultivation, hydrolytic H+ -ATPase activity, Vmax, Km, H+ -pumping activity, H+ permeability and pH gradient across the plasma membrane were significantly higher in rice roots grown at pH 3.0 than at 6.5, irrespective of the nitrogen forms supplied. The higher activity of plasma membrane H+ -ATPase of adapted rice roots was attributed to the increase in expression of OSA1, OSA3, OSA7, OSA8 and OSA9 genes, which resulted in an increase of H+ -ATPase protein concentration. In conclusion, a high regulation of various plasma membrane H+ -ATPase genes is responsible for the adaptation of rice roots to low pH. This mechanism may be partly responsible for the preference of rice plants to NH4+ nutrition. [source] | ||||||||||