Physiological characteristics of skeletal muscles of dogs and cats

Maxwell, L. C.; Barclay, J. K.; Mohrman, David E.; Faulkner, John A.

doi:10.1152/ajpcell.1977.233.1.c14

Cited by 113 publications

(62 citation statements)

References 20 publications

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“…1) The contraction pattern was obviously unphysiological (see above). 2) Fiber type composition of dog gastrocnemius muscle [predominantly constituted by type I and type IIa fibers (22)] is different compared with that of human muscle 5although the difference is small if endurance athletes are considered [e.g., see the review by Saltin and Gollnick (28)]6. 3) Resting Q to muscle, in control conditions, was 6-to 10-fold higher than those observed in humans (e.g., see Ref.…”

Section: Discussionmentioning

confidence: 99%

Faster adjustment of O₂delivery does not affect V˙o ₂ on-kinetics in isolated in situ canine muscle

Grassi

Gladden

Samaja

et al. 1998

Journal of Applied Physiology

222

267

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Grassi, Bruno, L. Bruce Gladden, Michele Samaja, Creed M. Stary, and Michael C. Hogan. Faster adjustment of O 2 delivery does not affect V O 2 on-kinetics in isolated in situ canine muscle. J. Appl. Physiol. 85(4): 1394-1403, 1998.-The mechanism(s) limiting muscle O 2 uptake (V O 2 ) kinetics was investigated in isolated canine gastrocnemius muscles (n ϭ 7) during transitions from rest to 3 min of electrically stimulated isometric tetanic contractions (200-ms trains, 50 Hz; 1 contraction/2 s; 60-70% of peak V O 2 ). Two conditions were mainly compared: 1) spontaneous adjustment of blood flow (Q ) [control, spontaneous Q (C Spont)]; and 2) pump-perfused Q , adjusted ϳ15 s before contractions at a constant level corresponding to the steady-state value during contractions in C Spont [faster adjustment of O 2 delivery (Fast O 2 Delivery)]. During Fast O 2 Delivery, 1-2 ml/min of 10 Ϫ2 M adenosine were infused intra-arterially to prevent inordinate pressure increases with the elevated Q . The purpose of the study was to determine whether a faster adjustment of O 2 delivery would affect V O 2 kinetics. Q was measured continuously; arterial (Ca O 2 ) and popliteal venous (Cv O 2 ) O 2 contents were determined at rest and at 5-to 7-s intervals during contractions; O 2 delivery was calculated as Q ·Ca O 2 , and V O 2 was calculated as Q · arteriovenous O 2 content difference. Times to reach 63% of the difference between baseline and steady-state V O 2 during contractions were 23.8 Ϯ 2.0 (SE) s in C Spont and 21.8 Ϯ 0.9 s in Fast O 2 Delivery (not significant). In the present experimental model, elimination of any delay in O 2 delivery during the rest-tocontraction transition did not affect muscle V O 2 kinetics, which suggests that this kinetics was mainly set by an intrinsic inertia of oxidative metabolism. gas exchange kinetics; muscle oxidative metabolism; submaximal exercise IT HAS BEEN KNOWN FOR DECADES that on a step transition from rest to exercise, or from a lower to a higher workload, O 2 uptake (V O 2 ) lags behind the power output increase (12), following a time course usually termed V O 2 on-kinetics. The mechanism(s) determining this kinetics has been a matter of considerable debate, mainly between those who consider it mainly related to the rate of adjustment of O 2 delivery to the exercising muscles (13-15) and those who support the concept that V O 2 on-kinetics is mainly set by an inertia of intramuscular oxidative metabolism (3, 32).An experimental approach to discriminate between the two conflicting hypotheses would be to increase the rate of adjustment of O 2 delivery to muscles and then determine whether the V O 2 on-kinetics becomes faster or not. Unfortunately, previous studies conducted following this approach yielded conflicting results. Hughson and co-workers (14), for example, described a significantly faster V O 2 on-kinetics when their subjects cycled in a supine position during the application of lower body negative pressure, which presumably enhanced the rate of O 2 delivery to the exercis...

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Section: Discussionmentioning

confidence: 99%

Faster adjustment of O₂delivery does not affect V˙o ₂ on-kinetics in isolated in situ canine muscle

Grassi

Gladden

Samaja

et al. 1998

Journal of Applied Physiology

222

267

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“…All excised muscle tissue was immediately frozen (Ͻ2 s) by submersion in liquid nitrogen. Biochemical and histochemical analyses have shown that the canine gracilis muscle (typically weighing ϳ25 g in a 1-yr-old beagle dog) has a fiber type composition of ϳ40% type I and ϳ60% type IIa fibers (22). The canine gracilis muscle is comparable in fiber type composition to human skeletal muscle, and the model used here allows multiple biopsy sampling without a severe detriment to contractile function (27, 28, 34 -36).…”

Section: Methodsmentioning

confidence: 99%

Acetyl-CoA provision and the acetyl group deficit at the onset of contraction in ischemic canine skeletal muscle

Roberts

Loxham²,

Poucher³

et al. 2005

American Journal of Physiology-Endocrinology and Metabolism

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-We examined the effects of increasing acetylcarnitine and acetyl-CoA availability at rest, independent of pyruvate dehydrogenase complex (PDC) activation, on energy production and tension development during the rest-to-work transition in canine skeletal muscle. We aimed to elucidate whether the lag in PDC-derived acetyl-CoA delivery toward the TCA cycle at the onset of exercise can be overcome by increasing acetyl group availability independently of PDC activation or is intimately dependent on PDCderived acetyl-CoA. Gracilis muscle pretreated with saline or sodium acetate (360 mg/kg body mass) (both n ϭ 6) was sampled repeatedly during 5 min of ischemic contraction. Acetate increased acetylcarnitine and acetyl-CoA availability (both P Ͻ 0.01) above control at rest and throughout contraction (P Ͻ 0.05), independently of differences in resting PDC activation between treatments. Acetate reduced oxygen-independent ATP resynthesis ϳ40% (P Ͻ 0.05) during the first minute of contraction. No difference in oxygen-independent ATP resynthesis existed between treatments from 1 to 3 min of contraction; however, energy production via this route increased ϳ25% (P Ͻ 0.05) above control in the acetate-treated group during the final 2 min of contraction. Tension development was ϳ20% greater after 5-min contraction after acetate treatment than in control (P Ͻ 0.05). In conclusion, at the immediate onset of contraction, when PDC was largely inactive, increasing cellular acetyl group availability overcame inertia in mitochondrial ATP regeneration. However, after the first minute, when PDC was near maximally activated in both groups, it appears that PDC-derived acetyl-CoA, rather than increased cellular acetyl group availability per se, dictated mitochondrial ATP resynthesis.acetylcarnitine; oxygen deficit; oxidative phosphorylation; phosphocreatine; sodium acetate THE READJUSTMENT of oxidative (mitochondrial) ATP production to meet the increase in muscular energy demand during the transition from rest to exercise, or the step increase from one workload to another, is delayed and follows an approximately exponential time course (for review, see Ref. 37). During this period of latency, the transient shortfall in mitochondrial ATP production, classically termed the "oxygen deficit" (21, 30), is supplemented by ATP resynthesis from non-oxygen-dependent routes [i.e., ATP and phosphocreatine (PCr) breakdown and glycolysis]. Although ATP production from oxygen-independent routes enables rapid rates of ATP turnover to be achieved, it has only a finite capacity and also results in the accumulation of metabolic byproducts that are deleterious to muscular contractile function (hydrogen ions, lactate ions, and inorganic phosphate; see Ref. 8). Indeed, without the progressive increase in mitochondrial ATP production at the onset of contraction, the onset of muscular fatigue would be markedly accelerated. Classically, the lag in oxidative ATP production and resulting oxygen deficit have been attributed to a lag in muscle blood flow and thereby m...

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“…The goal of this study was to determine whether a 33-electrode spiral cuff could be used to selectively collect the sensory information from the sciatic nerve of a dog. In particular, we wanted to know if an ENG could be recorded selectively from nerve fibers within superficial regions of a dog's sciatic nerve innervating mainly muscle spindles and Golgi tendon organs of the tibialis anterior (TA) and gastrocnemius (GM) muscles [19].…”

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confidence: 99%

Selective Recording of Electroneurograms from the Sciatic Nerve of a Dog with Multi-Electrode Spiral Cuffs.

Rozman

Zorko²,

Bunc³

2000

JJP

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Physiological characteristics of skeletal muscles of dogs and cats

Cited by 113 publications

References 20 publications

Faster adjustment of O₂delivery does not affect V˙o ₂ on-kinetics in isolated in situ canine muscle

Faster adjustment of O₂delivery does not affect V˙o ₂ on-kinetics in isolated in situ canine muscle

Acetyl-CoA provision and the acetyl group deficit at the onset of contraction in ischemic canine skeletal muscle

Selective Recording of Electroneurograms from the Sciatic Nerve of a Dog with Multi-Electrode Spiral Cuffs.

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Physiological characteristics of skeletal muscles of dogs and cats

Cited by 113 publications

References 20 publications

Faster adjustment of O2delivery does not affect V˙o 2 on-kinetics in isolated in situ canine muscle

Faster adjustment of O2delivery does not affect V˙o 2 on-kinetics in isolated in situ canine muscle

Acetyl-CoA provision and the acetyl group deficit at the onset of contraction in ischemic canine skeletal muscle

Selective Recording of Electroneurograms from the Sciatic Nerve of a Dog with Multi-Electrode Spiral Cuffs.

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Faster adjustment of O₂delivery does not affect V˙o ₂ on-kinetics in isolated in situ canine muscle

Faster adjustment of O₂delivery does not affect V˙o ₂ on-kinetics in isolated in situ canine muscle