Oxygen dependence of respiration in coupled and uncoupled endothelial cells
- 1 December 1996
- journal article
- research article
- Published by American Physiological Society in American Journal of Physiology-Cell Physiology
- Vol. 271 (6) , C2053-C2061
- https://doi.org/10.1152/ajpcell.1996.271.6.c2053
Abstract
We studied the oxygen dependence of respiration in cultured human umbilical vein endothelial cells by use of high-resolution respirometry. The rate of oxygen consumption varied from 30 to 50 pmol O2.s-1.(10(6) cells)-1 over a sixfold range of cell densities. Respiration was stimulated up to 3.5-fold by uncoupling with carbonyl cyanide p-trifluoromethoxyphenylhydrazone or 2,4-dinitrophenol, and the PO2 at half-maximal respiration (P50) increased from 0.05 to 0.12 kPa (0.3 to 0.9 Torr) with respiratory rate. P50 decreased to a minimum of 0.02 kPa when uncoupled cells were inhibited to control levels. Differences in cell size explained a variation of approximately 0.015 kPa in P50 at similar respiratory rates per cell. Oxygen diffusion to mitochondria contributed maximally 30% to the regulation of P50 in coupled cells, as deduced from the shallow slope of the flux dependence of P50 in uncoupled-inhibited cells compared with the slope in coupled cells. Therefore 70% of the flux dependence of P50 in coupled cells was caused by changes in metabolic state, which correlated with respiratory rate.Keywords
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