Normal effect of insulin to stimulate leg blood flow in NIDDM

Premature lactic acidosis during exercise in patients with chronic obstructive pulmonary disease (COPD) may play a role in exercise intolerance. In this study, we evaluated whether the early exercise-induced lactic acidosis in these individuals can be explained by changes in peripheral O2 delivery (D˙o 2). Measurements of leg blood flow by thermodilution and of arterial and femoral venous blood gases, pH, and lactate were obtained during a standard incremental exercise test to capacity in eight patients with severe COPD and in eight age-matched controls. No significant difference was found between the two groups in leg blood flow at rest or during exercise at the same power outputs. Blood lactate concentrations and lactate release from the lower limb were greater in COPD patients at all submaximal exercise levels (all P < 0.05). LegD˙o 2at a given power output was not significantly different between the two groups, and no significant correlation was found between this parameter and blood lactate concentrations. COPD patients had lower arterial and venous pH at submaximal exercise, and there was a significant positive correlation between venous pH at 40 W and the peak O2 uptake ( r = 0.91, P < 0.0001). The correlation between venous pH and peak O2 uptake suggests that early muscle acidosis may be involved in early exercise termination in COPD patients. The early lactate release from the lower limb during exercise could not be accounted for by changes in peripheralD˙o 2. The present results point to skeletal muscle dysfunction as being responsible for the early onset of lactic acidosis in COPD.

Download Full-text

Oxygen transport to exercising leg in chronic hypoxia

Journal of Applied Physiology ◽

10.1152/jappl.1988.65.6.2592 ◽

1988 ◽

Vol 65 (6) ◽

pp. 2592-2597 ◽

Cited By ~ 74

Author(s):

P. R. Bender ◽

B. M. Groves ◽

R. E. McCullough ◽

R. G. McCullough ◽

S. Y. Huang ◽

...

Keyword(s):

Blood Flow ◽

Sea Level ◽

Chronic Hypoxia ◽

Peripheral Resistance ◽

Hemoglobin Concentration ◽

Barometric Pressure ◽

Ambient Air ◽

Leg Blood Flow ◽

State Cycle ◽

O2 Delivery

Residence at high altitude could be accompanied by adaptations that alter the mechanisms of O2 delivery to exercising muscle. Seven sea level resident males, aged 22 +/- 1 yr, performed moderate to near-maximal steady-state cycle exercise at sea level in normoxia [inspired PO2 (PIO2) 150 Torr] and acute hypobaric hypoxia (barometric pressure, 445 Torr; PIO2, 83 Torr), and after 18 days' residence on Pikes Peak (4,300 m) while breathing ambient air (PIO2, 86 Torr) and air similar to that at sea level (35% O2, PIO2, 144 Torr). In both hypoxia and normoxia, after acclimatization the femoral arterial-iliac venous O2 content difference, hemoglobin concentration, and arterial O2 content, were higher than before acclimatization, but the venous PO2 (PVO2) was unchanged. Thermodilution leg blood flow was lower but calculated arterial O2 delivery and leg VO2 similar in hypoxia after vs. before acclimatization. Mean arterial pressure (MAP) and total peripheral resistance in hypoxia were greater after, than before, acclimatization. We concluded that acclimatization did not increase O2 delivery but rather maintained delivery via increased arterial oxygenation and decreased leg blood flow. The maintenance of PVO2 and the higher MAP after acclimatization suggested matching of O2 delivery to tissue O2 demands, with vasoconstriction possibly contributing to the decreased flow.

Download Full-text

Exercise training enhances leg vasodilatory capacity of 65-yr-old men and women

Journal of Applied Physiology ◽

10.1152/jappl.1990.69.5.1804 ◽

1990 ◽

Vol 69 (5) ◽

pp. 1804-1809 ◽

Cited By ~ 62

Author(s):

W. H. Martin ◽

W. M. Kohrt ◽

M. T. Malley ◽

E. Korte ◽

S. Stoltz

Keyword(s):

Blood Flow ◽

Body Weight ◽

Exercise Training ◽

Oxygen Uptake ◽

Endurance Exercise ◽

Maximal Oxygen Uptake ◽

Statistical Significance ◽

Tissue Loss ◽

Leg Blood Flow ◽

Endurance Exercise Training

To determine whether extremity vasodilatory capacity may be augmented in older persons by endurance exercise training, lower leg blood flow and conductance were characterized plethysmographically at rest and during maximal hyperemia in 9 men and 10 women aged 64 +/- 3 (SD) yr before and after 31 +/- 6 wk of walking and jogging at 70-90% of maximal oxygen uptake for 45 min 3-5 days/wk. Maximal oxygen uptake expressed as milliliters per kilogram per minute improved 25% in men and 21% in women (P less than 0.01). Maximal leg blood flow and conductance increased in all nine men by an average of 39 +/- 33 (P less than 0.001) and 42 +/- 44% (P less than 0.004), respectively. Results were more variable in women and achieved unequivocal statistical significance only for maximal blood flow (+33 +/- 54% for blood flow and +29 +/- 55% for conductance; P less than 0.02 and P = 0.05, respectively). Body weight and skinfold adiposity declined in both sexes (P less than 0.05). Enhancement of vasodilatory capacity was related to weight loss in men and adipose tissue loss in women (r = 0.61 and 0.51, respectively; P less than 0.05). There were no significant changes in exercise capacity, body weight, or maximal blood flow in four male and three female controls aged 66 +/- 4 yr. Thus adaptability of the lower limb circulation to endurance exercise training is retained to at least age 65 yr.

Download Full-text