Increased plasma O2 solubility improves O2 uptake of in situ dog muscle working maximally

Abstract

A perfluorocarbon emulsion [formulation containing 90% wt/vol perflubron (perfluorooctylbromide); Alliance Pharmaceutical] was used to increase O2 solubility in the plasma compartment during hyperoxic low hemoglobin concentration ([Hb]) perfusion of a maximally working dog muscle in situ. Our hypothesis was that the increased plasma O2 solubility would increase the muscle O2 diffusing capacity (DO2) by augmenting the capillary surface area in contact with high [O2]. Oxygen uptake (VO2) was measured in isolated in situ canine gastrocnemius (n = 4) while working for 6 min at a maximal stimulation rate of 1 Hz (isometric tetanic contractions) on three to four separate occasions for each muscle. On each occasion, the last 4 min of the 6-min work period was split into 2 min of a control treatment (only emulsifying agent mixed into blood) and 2 min of perflubron treatment (6 g/kg body wt), reversing the order for each subsequent work bout. Before contractions, the [Hb] of the dog was decreased to 8-9 g/100 ml and arterial PO2 was increased to 500-600 Torr by having the dog breathe 100% O2 to maximize the effect of the perflubron. Muscle blood flow was held constant between the two experimental conditions. Plasma O2 solubility was almost doubled to 0.005 ml O2 x 100 ml blood-1 x Torr-1 by the addition of the perflubron. Muscle O2 delivery and maximal VO2 were significantly improved (at the same blood flow and [Hb]) by 11 and 12.6%, respectively (P < 0.05), during the perflubron treatment compared with the control. O2 extraction by the muscle remained the same between the two treatments, as did the estimate of DO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of single and combined Mycoplasma gallisepticum vaccinations on blood electrolytes and acid-base balance in commercial egg-laying hens

“…Significant increases in the levels of arterial pO 2 , along with concomitant decreases in pCO 2 , have been reported in pneumocystis-infected mice (Qureshi et al, 2003) and also, more recently, in MG-inoculated layers (Olanrewaju et al, 2009). An increase in mixed venous pO 2 levels is suggestive of an improvement in global oxygenation status (Hogan et al, 1992). Conversely, high pCO 2 has been reported to suppress the immune response in various human peritoneal cells (Kopernik et al, 1998).…”

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“…oxygen bypassing the microcirculation). This view is substantiated by a study that demonstrated an increase of oxygen consumption in a maximally working, in-situ gastrocnemius muscle preparation in anesthetized and haemodiluted dogs after Oxygent administration [12]. It is also substantiated by the fact that increases in mixed venous oxygen partial pressure are generally associated with an Oxygent-dependent improvement in tissue oxygenation, as demonstrated in the heart, brain, muscle, gut and liver [13,14].…”

“…An increase in mixed venous oxygen partial pressure indicates improvement in global oxygenation status [12], rather than shunting of oxygen from arterioles directly into venules (i.e. oxygen bypassing the microcirculation).…”

Oxygent™ as a Top Load to Colloid and Hyperoxia Is More Effective in Resuscitation From Hemorrhagic Shock Than Colloid and Hyperoxia Alone

“…Today, it is believed that under normoxia, red cells resemble distinct O 2 sources within the microcirculation, and that plasma acts primarily as a diffusion barrier (26,27). This becomes even more pronounced during profound dilutional anemia, when the longitudinal distance between red cells is increased within the microvessels and the diffusive resistance of the larger plasma layer increases (7,28). This explains why it is highly desirable to increase the amount of physically dissolved O 2 in plasma: it makes O 2 independent from distinct O 2 sources (i.e., red cells) and changes plasma from a primary diffusion barrier into a ubiquitous source of O 2 .…”

“…administration. PFCs are excellent gas solvents and therefore increase the O 2 plasma solubility approximately 20-fold (7). The relationship between O 2 partial pressure and O 2 content in a PFC is linear and obeys Henry's law (8).…”