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Evidence for nonclassical respiratory activity from oxygen gradient measurements in tissue slices
Journal article   Peer reviewed

Evidence for nonclassical respiratory activity from oxygen gradient measurements in tissue slices

Donald G. Buerk and Ian S. Longmuir
Microvascular research, v 13(3), pp 345-353
1977
DOI: https://doi.org/10.1016/0026-2862(77)90101-7
PMID: 875757

Abstract

Direct measurement of steady-state oxygen concentration gradients using oxygen-sensitive recessed microelectrodes (2- to 4-μm tip size) were obtained in brain and liver slices. Experimental observations were normalized to examine the deviation from a classical passive diffusion model with concentration-independent (zero-order) chemical reaction kinetics. Discrepancies were noted between gradients measured during inward or outward electrode movement, which can be attributed to tissue compression effects. Gradients obtained during outward electrode movement were therefore judged to be more accurate than gradients measured during inward movement. Concentration gradients from both tissue types demonstrated significant departures from the gradient predicted by classical respiratory activity. A tendency towards a greater departure from the classical model was observed for gradients obtained in liver. The shape of the observed normalized gradients indicates that oxygen diffuses further into the tissue than predicted by the classical model. Nonclassical models of respiratory activity must be formulated to account for the experimental results from brain and liver tissues observed in this study.

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