David Poole

..g., exercise training and anti-inflammatory, antioxidant strategies, in particular) and hence patient exercise tolerance and quality of life are presented within their appropriate context of the O(2) transport pathway...

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..To determine whether the phosphorescent probe Oxyphor R2 (a palladium porphyrin dendrimer) becomes extravasated within normotensive skeletal muscle, R2 perfusion and washout studies were performed using a perfused rat hindlimb preparation...

..Moreover, our findings suggest that alterations in V(RBC) do not obligate proportional changes in Hct(CAP) within individual capillaries following muscle contractions...

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..Novel microcirculatory investigations reveal that elevated capillary-to-myocyte O2 flux in rat muscle is, in fact, initiated simultaneously with contractions...

..g. diabetes, CHF) and may help explain the compromised exercise tolerance present in aged individuals. Putative mechanistic insights are explored within the context of current knowledge and future investigative approaches...

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..This revision is essential if we are to understand the control of microcirculatory O(2) and substrate flux in health and resolve the mechanistic bases by which these processes are compromised in diseases such as chronic heart failure...

..This provides empirical evidence in support of one possible mechanism for respiratory muscle failure in emphysema...

..Knowledge of capillary function in healthy muscle is requisite for identification of pathology and efficient design of therapeutic treatments...

..Whereas muscle conductive O2 delivery and capillary hematocrit were unchanged, elevated VRBC reduces capillary RBC transit time and may impair the diffusive transport of O2 from blood to myocyte particularly under exercise conditions...

..These alterations likely contribute to the mechanisms responsible for the reduced exercise capacity commonly found in elderly populations...

..Thus CHF impairs diffusive and conductive O2 delivery across the rest-to-contractions transition in rat skeletal muscle, which may help explain the slowed O2 uptake on-kinetics manifested in CHF patients at exercise onset...

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..If these microcirculatory deficits are present during exercise, it may provide a basis for the reduced O(2) exchange characteristic of Type II diabetic patients...

..8 +/- 3.2 Torr; at 2 min of recovery: 25.0 +/- 1.4 Torr; P < 0.05). We conclude that LRC is not a prerequisite for achievement of Ve commensurate with maximal exercise or the pronounced hyperventilation during recovery...

..These results enhance our understanding of the role of NO-mediated circulatory control by demonstrating that nNOS does not appear to subserve an obligatory role in the exercising muscle hyperaemic response in the rat...

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..4 +/- 4.3 s; after, 15.6 +/- 2.7 s; P < 0.05). These results demonstrate that antioxidant supplementation significantly impacts the control of (Q(O(2)m/V(O(2)m)) in young rats at rest and during contractions...

..These data suggest that following high-intensity, though submaximal, muscle contractions, Pmvo(2) recovers much faster in the more oxidative mixed gastrocnemius than in the less oxidative white gastrocnemius...

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..Moreover, the greater degree of P(O)(2)mv on-off asymmetry in the aged muscle suggests a mechanistic link between impaired microvascular oxygenation and altered muscle metabolic responses during exercise transitions...

..These results may explain, in part, the slowed recovery kinetics (phosphocreatine and VO2) and pronounced fatigue following muscular work in CHF patients...

..g. more rapid increase in oxidative phosphorylation) may be responsible for the increased speed of P(O2,m) kinetics after prior contractions under these conditions...

..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...

..Compared with CON, this decreased PmvO2 across the transition to a higher metabolic rate in Type II diabetes would be expected to impair blood-muscle O2 exchange and contractile function...

..differences result from the lower resting Q in FT muscles...

..According to Fick's law, this scenario will decrease blood-myocyte O2 flux, thereby slowing Vo2 kinetics and exacerbating the O2 deficit generated at exercise onset...

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..prior to, exercise, lends important insights into the integrated nature of vascular control during exercise...

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..This phenomenon is qualitatively similar to that reported previously for healthy young and old rats...

..4 +/- 0.7; L-NAME, 4.7 +/- 1.2 L; P = 0.06). These data support the notion that NO contributes prominently to the oxidative enzyme inertia and thus the speed of V(O(2)) kinetics at the onset of moderate intensity exercise in the horse...

..The severe exercise intensity domain may be defined as that range of work rates over which .VO(2max) can be elicited during constant-load exercise. The purpose of this study was to help characterize the .VO(2) response within this domain...

..In conclusion, these data demonstrate that, despite similar increases in total hindlimb BF in Y and O rats during submaximal Ex, there is a profound BF redistribution from highly oxidative to highly glycolytic muscles...

..e., the mechanisms of altered microcirculatory control by transmission light microscopy)...

..These results revealed that the main determinant of CvO(2) (or O(2) extraction) kinetics was the dynamic interaction of Q (m) and V O(2m) kinetics during phase 1 of Q (m)...

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..Thus, in marked contrast to healthy humans, pronounced V-slope (increase VCO2/VO2) behavior occurs in TB concomitant with elevated PaCO2 and without evidence of a ventilatory threshold...

..In contrast to humans, LT is a poor analogue of Tge in the horse...

..slow-twitch muscle and 2) various patient populations, such as those with congestive heart failure and diabetes mellitus...

..01) indexes of heart failure. The present investigation suggests that slowed Pmv(O(2)) kinetics during recovery in CHF constitutes a mechanistic link between impaired circulatory and metabolic recovery after contractions in CHF...

..If such standardization is not feasible, it should be recognized that specific analysis protocols may exert a substantial effect upon the reported VO(2peak)...

..4+/-0.3 to 37.1+/-1.0 mmHg (P<0.05). These data indicate that the Asian elephant can endure at least short periods of LR without lowering arterial O(2) content...

..These results have significant implications for improving and refining exercise testing and experimental designs...

..e., reduced economy during contractions), which mechanistically may underlie, in part, the reduced exercise tolerance in conditions associated with oxidative stress...

..These data validate the powerful CS construct in the rat and identify that running above CS, relative to below CS, incurs disproportionate blood flow increases (indicative of recruitment) in predominantly highly glycolytic muscle fibres...

..This paper provides an overview of some of the factors which might contribute to both the fundamental and slow phases of the VO(2) kinetics and, in so doing, provides general background material for the more specific papers that follow...

..In conclusion, the dynamics of quadriceps microvascular oxygenation demonstrates substantial spatial heterogeneity that must arise from disparities in the relative kinetics of Vo(2) and O(2) delivery increase across the regions sampled...

..These results also indicate that the greater sustained P(mvO(2)) in Sol may be important for ensuring high blood-myocyte O(2) flux and therefore a greater oxidative contribution to energetic requirements...

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..p.m.; 29.4 +/- 2.8 ml min(-1) kg(-1) at 100 r.p.m., P < 0.05). We conclude that CP represents a specific metabolic rate (VO2) which can be achieved at different combinations of power outputs and pedalling frequencies...

..These findings provide a clear mandate for rejecting these secondary criteria as a means of validating VO(2max) on ramp exercise tests...

..e., H(+) concentration and [P(i)]), which have been associated with the fatigue process...

..In conclusion, in vivo quantitative analyses demonstrated that ECC contractions elevate [Ca2+]i significantly more than ISO contractions and that stretch-activated channels may play a permissive role in this response...

..e., a microvascular O(2) delivery-to-O(2) requirement mismatch or oxidative enzyme inertia...

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..These differences in skeletal metabolism and strength may help explain some of the skeletal changes associated with chronic obstructive pulmonary disease in humans...

..68, p<0.0001) and was in the rank order of type IIA > I > IIX > IIB. These data demonstrate that hamster skeletal muscle is predominantly composed of type IIB and IIX fibers...

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