Effects of Type II diabetes on muscle microvascular oxygen pressures

We tested the hypothesis that muscle microvascular O2 pressure (PmvO2PmvO2; reflecting the O2 delivery (Q˙O2) to O2 uptake (V˙O2) ratio) would be lowered in the spinotrapezius muscle of Goto–Kakizaki (GK) Type II diabetic rats (n = 7) at rest and during twitch contractions when compared to control (CON; n = 5) rats. At rest, PmvO2PmvO2 was lower in GK versus CON rats (CON: 29 ± 2; GK: 18 ± 2 Torr; P < 0.05). At the onset of contractions, GK rats evidenced a faster change in PmvO2PmvO2 than CON (i.e., time constant (τ); CON: 16 ± 4; GK: 6 ± 2 s; P < 0.05). In contrast to the monoexponential fall in PmvO2PmvO2 to the steady-state level seen in CON, GK rats exhibited a biphasic PmvO2PmvO2 response that included a blunted (or non-existent) PmvO2PmvO2 decrease followed by recovery to a steady-state PmvO2PmvO2 that was at, or slightly above, resting values. Compared with CON, this decreased PmvO2PmvO2 across the transition to a higher metabolic rate in Type II diabetes would be expected to impair blood-muscle O2 exchange and contractile function.