Red blood cell derived extracellular vesicles during the process of autologous blood doping

The purpose of this pilot study was to investigate the effects of the transfusion of one erythrocyte concentrate on the number of circulating red blood cell extracellular vesicles (RBC-EVs) and their clearance time. Six, healthy volunteers donated their blood and were transfused with their RBC concentrate after 35-36 days of storage. One K₂ EDTA and one serum sample were collected before donation, at four timepoints after donation and at another six timepoints after transfusion. RBC-EVs were analyzed on a Cytek Aurora flow cytometer. A highly significant increase (p < 0.001) of RBC-EVs from an average of 60.1 ± 19.8 (10³ /μL) at baseline to 179.3 ± 84.7 (10³ /μL) in the first 1-3 h after transfusion could be observed. Individual differences in the response to transfusion became apparent with one volunteer showing no increase and another an increased concentration at one timepoint after donation due to an influenza infection. We concluded that in an individualized passport approach, increased RBC-EVs might be considered as additional evidence when interpreting suspicious Athletes Biological Passport (ABPs) but for this additional research related to sample collection and transport processes as well as method development and harmonization would be necessary.

Effect of hypoxia on intracellular pH of glomus cells cultured from cat and rat carotid bodies

To test the hypothesis that hypoxia may induce cellular acidification during chemotransduction in the carotid body, we compared the effects of hypoxia and of extracellular acidosis on intracellular pH (pHi) of glomus cells cultured from rat and cat carotid bodies. The cells were prepared and cultured for 2-7 days. The plated cells were loaded with a pH-sensitive fluorescent probe, SNARF-1-acetoxymethyl ester, and were placed in a closed chamber and superfused. The effects of lowering PO2 and pH in the superfusion medium containing CO2-HCO3- buffer on the glomus cell pHi were measured at 37 degrees C. The pHi was measured in a single or a few isolated cells with single excitation at 540 nm and dual emission at 590 and 640 nm, after the exposure to different PO2 levels from 132 to 43, 14, and 1-2 Torr for 10-12 min in the closed chamber. The resting pHi values were 7.263 +/- 0.008 for rat and 7.175 +/- 0.004 for cat carotid body glomus cells. For a decrease of PO2 from 132 Torr to 14 Torr, the change in pHi values, on average, for cat and rat glomus cells was 0.034 lower, and with PO2 decrease to 1-2 Torr for the cat glomus cells, the change in pHi values was 0.051 lower. On the other hand, when the perfusate pH values were decreased from 7.4 to 6.9 during normoxia, the reduction of change in pHi values were 0.327 for the rat and 0.397 for the cat. Thus glomus cell pHi change due to low PO2 exposure was not significant and was not commensurate with the large increases in the chemosensory activity.

Nuclear magnetic resonance investigations of calcium antagonist drugs. II: Conformational and dynamic features of verapamil in [2H6]DMSO

Conformational features of verapamil in [2H6]DMSO have been delineated by measuring 13C and 1H NMR parameters. Spin-lattice relaxation rates were interpreted within the frame of an extended alkane chain with segmental motions hampered by the aromatic substituents at both ends. The effective correlation times were all evaluated in the range 0.16-0.22 ns at 293 K. The aromatic rings were found to lie somewhat out-of-plane with the alkane chain. The NMR data were used to construct a Dreiding model of the most probable spatial arrangement and a molecular modeling system was utilized to represent the "preferred" conformation of verapamil in solution.