Dynamics of microvascular oxygen pressure during rest-contraction transition in skeletal muscle of diabetic rats.
Type I diabetes reduces dramatically the capacity of skeletal muscle to receive oxygen (QO(2)). In control (C; n = 6) and streptozotocin-induced diabetic (D: n = 6, plasma glucose = 25.3 +/- 3.9 mmol/l and C: 8.3 +/- 0.5 mmol/l) rats, phosphorescence quenching was used to test the hypothesis that, in D rats, the decline in microvascular PO(2) [Pm(O(2)), which reflects the dynamic balance between O(2) utilization (VO(2)) and QO(2)] of the spinotrapezius muscle after the onset of electrical stimulation (1 Hz) would be faster compared with that of C rats. Pm(O(2)) data were fit with a one or two exponential process (contingent on the presence of an undershoot) with independent time delays using least-squares regression analysis. In D rats, Pm(O(2)) at rest was lower (C: 31.2 +/- 3.2 mmHg; D: 24.3 +/- 1.3 mmHg, P < 0.05) and at the onset of contractions decreased after a shorter delay (C: 13.5 +/- 1.8 s; D: 7.6 +/- 2.1 s, P < 0.05) and with a reduced mean response time (C: 31.4 +/- 3.3 s; D: 23.9 +/- 3.1 s, P < 0.05). Pm(O(2)) exhibited a marked undershoot of the end-stimulation response in D muscles (D: 3.3 +/- 1.1 mmHg, P < 0.05), which was absent in C muscles. These results indicate an altered VO(2)-to-QO(2) matching across the rest-exercise transition in muscles of D rats.
Department of Kinesiology, Kansas State University, Manhattan, Kansas 66506-5802, USA.
Bradley J
BJ
Behnke
Casey A
CA
Kindig
Paul
P
McDonough
David C
DC
Poole
William L
WL
Sexton
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D005260:Female; D008833:Microcirculation / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology*; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012146:Rest / Q000502:physiology
D010100:Oxygen