Erythrocyte‐shape evolution recorded with fast‐measurement NMR diffusion–diffraction

Abstract

To monitor red blood cell (RBC) shape evolution by (1)H(2)O diffusion-diffraction NMR in time steps comparable to those required for the acquisition of a (31)P NMR spectrum; thus, to correlate RBC mean diameter with ATP concentration after poisoning with NaF. Pulsed-field gradient-stimulated echo (PFGSTE) diffusion experiments were recorded on (1)H(2)O in RBC suspensions. Under conditions of restricted diffusion, q-space experiments report on mean RBC diameter. To decrease experiment time, the phase cycling of radiofrequency (RF) pulses was cut to two transients by using unbalanced pairs of gradient pulses. Data processing used a recent digital filter. Differential interference contrast (DIC) light microscopy also recorded shape changes. (31)P NMR spectroscopy gave estimates of mean ATP concentration. NaF caused RBC-shape evolution from discocytes, through various forms of echinocytes, to spherocytes, over approximately 6 h and approximately 10 h at 37 degrees C and 25 degrees C, respectively. ATP declined to approximately 0.5 its normal concentration before the first stage of discocyte transformation; the concentration was 0.0 after approximately 1.5 h and 3.0 h, respectively, at the two temperatures. RBC shape was readily monitored by NMR with a temporal resolution that was useful for correlations with both DIC microscopy and (31)P NMR spectra.