Multiexponential analysis of diffusion exchange times reveals a distinct exchange process associated with metabolic activity

Contrary to prevailing views, recent work suggests that steady-state water exchange between the intra- and extracellular space is driven, in part, by active metabolic processes. To support these findings, we investigate whether exchange exhibits multiexponential behavior consistent with distinct exchange processes. We find a bimodal distribution of exchange times in live neural tissue, with only the faster peak being reduced upon the introduction of a sodium-potassium pump inhibitor, thus supporting the existence of active exchange. Furthermore, we describe a time-efficient method of isolating exchange and fitting multiexponential exchange times using diffusion exchange spectroscopy, paving the way for future studies.