Download Plasma Oxygen during Cardiopulmonary Bypass

I
Clinical Science ( 1997) 94, I (Printed in Great Britain)
Comment
Plasma oxygen during cardiopulmonary bypass
The paper by Petyaev et al. in this issue [l] draws
attention to an important but underestimated potential source of oxygen delivery to tissues, i.e. oxygen
associated with plasma lipids. Oxygen is more
soluble in lipids than in aqueous solution, but the
relative importance of plasma lipids for oxygen
transport has been unrecognized because of a lack
of suitable analytical techniques. Earlier this year
the same group published a chemical method for
measurement of lipid-associated oxygen [2] and have
now examined changes in the oxygen associated with
whole blood and lipid content of plasma before,
during and after cardiac surgery. They conclude that
monitoring lipid-associated oxygen may prove a better alternative to current methods of measuring oxygen status, although the relevance of measurements
has yet to be fully explored. What is clear is that
they have highlighted an important pool of circulating oxygen which may play significant roles in tissue
physiology and pathophysiology.
One possibility is that this oxygen associated with
lipids may predispose the lipids and lipoproteins to
oxidative degeneration by lipid peroxidation in the
presence of an appropriate source of reactive freeradical species. An alternative is that this lipidassociated oxygen may be an unrecognized source of
oxygen for tissues, transfer being facilitated by the
accessibility of blood lipids to tissues. The implications of these findings for the widespread use of
plasma-lipid lowering drugs will also require careful
consideration. Petyaev et al. [l]clearly show that the
oxygen in plasma has a linear correlation with total
plasma cholesterol levels. The question of whether
effective lipid-lowering programmes might lead to a
reduced availability of oxygen to tissues under certain conditions is therefore a relevant question
which will require further research.
M. J. Jackson
Department of Medicine, University Clinical
Depaments, Duncan BuiMing,
Dawby Street, Liverpool L69 3GA, U.K.
(ON BEHALF OF THE EDITORIAL BOARD)
REFERENCES
I. Petyaev IM, Vuylsteke A, Behtune DW,Hunt JV. P
m
l oxygen during
cardiopulmoMly bypass: a comparison of blood oxygen Mr with oxygen present
in plasma lipid. Clin. Sci 1998 94: 35-41.
2. Petyaev IM, Hunt JV. Micellar acceleration of oxygerrdependent reMions and its
potential use in the study of human low densii lipoprotein. Biochim Biophys &a
1997; I345 293-305.