Transmembrane potential measurements as an indicator of heterogeneous distribution of nutritive blood flow in skeletal muscle during shock.

Abstract

AbstractThe heterogeneity of nutritive skeletal muscle blood flow during shock was studied in terms of cellular transmembrane potential variations. Shock was induced in dogs by exteriorization of the small intestine for 3 h, whereafter the intestine was replaced and the dogs were studied for another 3–4 h. Transmembrane potentials of single skeletal muscle cells were recorded by the use of modified Ling‐Gerard microelectrodes. The mean resting transmembrane potential in control animals was ‐90.4 mV ± 0.7. The variation in transmembrane potential between adjacent fibers was small. During shock there was a significant decrease in the mean transmembrane potential and at the same time there was an increasing variation of up to 29 mV in the values between adjacent fibers. To exclude metabolic differences between red and white fibers as the main reason for this increasing heterogeneity of transmembrane potentials of adjacent fibers, complete tourniquet ischemia was also studied. The total tissue ischemia resulted in a marked reduction of the transmembrane potential in all cells with only small differences between adjacent fibers. After release of the tourniquet a marked spread of resting membrane potentials, with variations of 17–25 mV between adjacent fibers, occurred. This variation was similar to that observed during shock. It is concluded that repeated transmembrane potential registrations may reveal the variable state of adjacent cells subjected to a heterogeneous nutritive blood flow in shock.