Effects of Type II diabetes on muscle microvascular oxygen pressures

We tested the hypothesis that muscle microvascular O-2 pressure (P-mvO2; reflecting the O-2 delivery (Q(O2)) to O-2 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, P-mvO2 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 P-mvO2 than CON (i.e., time constant (tau); CON: 16 +/- 4; GK: 6 +/- 12 s; P < 0.05). In contrast to the monoexponential fall in P-mvO2 to the steady-state level seen in CON, GK rats exhibited a biphasic P-mvO2 response that included a blunted (or non-existent) P-mvO2, decrease followed by recovery to a steady-state P-mvO2 that was at, or slightly above, resting values. Compared with CON, this decreased P-mvO2 across the transition to a higher metabolic rate in Type II diabetes would be expected to impair blood-muscle 02 exchange and contractile function. (c) 2006 Elsevier B.V All rights reserved.