Role of convective O(2) delivery in determining VO(2) on-kinetics in canine muscle contracting at peak VO(2).
Role of convective O(2) delivery in determining VO(2) on-kinetics in canine muscle contracting at peak VO(2).
复制标题
对流 O(2) 输送在确定 VO(2) 峰值 VO(2) 时犬肌肉收缩动力学中的作用。
DOI：
10.1152/jappl.2000.89.4.1293
复制
发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Gladden,LB
中科院分区：
文献类型：
--
作者：
Grassi,B;Hogan,MC;Kelley,KM;Aschenbach,WG;Hamann,JJ;Evans,RK;Patillo,RE;Gladden,LB
之前的一项研究（Grassi B、Gladden LB、Samaja M、Stary CM和Hogan MC，J Appl Physiol 85：1394-1403，1998）表明，在从休息到收缩的过渡期间，向肌肉对流输送O2并不会限制动力学上的O2吸收（V o2）在峰值V o2的0.60%。本研究的目的是确定这一发现是否也是真实的过渡涉及收缩的更高的代谢intensity.V steco 2 on动力学确定在离体犬腓肠肌肌肉原位（n= 5）在过渡期间从休息到4分钟的电刺激等长强直收缩对应的肌肉peakV steco 2。比较了两种条件：1）肌肉血流量的自发调节（Q stec）（对照）和2）泵灌注Q stec，在收缩前15-30 s将其调节至与对照（快速O2输送）收缩期间的稳态值相对应的恒定水平。在Fast O2 Delivery中，动脉内输注腺苷。在腘静脉连续测量Q stec;在休息时和过渡期间以5- 7-s的间隔测量动脉和腘静脉的O2含量。肌肉Vsteco 2测定为Q steces乘以动静脉血氧含量差。对照组达到静息基线和收缩期间稳态值之间Vsteco 2差值63%的时间为24.9 ± 1.6（SE）s，快速供氧组为18.5 ± 1.8 s（P< 0.05）。快速氧输送中的FasterV steco 2 on动力学与计算的氧不足减少约30%和肌肉疲劳减少相关。在过渡涉及收缩在峰值V steco 2，对流O2输送到肌肉，连同氧化代谢的惯性，有助于确定theV steco 2 on动力学。
A previous study (Grassi B, Gladden LB, Samaja M, Stary CM, and Hogan MC,J Appl Physiol85: 1394–1403, 1998) showed that convective O2delivery to muscle did not limit O2uptake (V˙o2) on-kinetics during transitions from rest to contractions at ∼60% of peakV˙o2. The present study aimed to determine whether this finding is also true for transitions involving contractions of higher metabolic intensities.V˙o2on-kinetics were determined in isolated canine gastrocnemius muscles in situ (n= 5) during transitions from rest to 4 min of electrically stimulated isometric tetanic contractions corresponding to the muscle peakV˙o2. Two conditions were compared:1) spontaneous adjustment of muscle blood flow (Q˙) (Control) and2) pump-perfused Q˙, adjusted ∼15–30 s before contractions at a constant level corresponding to the steady-state value during contractions in Control (Fast O2Delivery). In Fast O2Delivery, adenosine was infused intra-arterially. Q˙ was measured continuously in the popliteal vein; arterial and popliteal venous O2contents were measured at rest and at 5- to 7-s intervals during the transition. Muscle V˙o2was determined as Q˙times the arteriovenous blood O2content difference. The time to reach 63% of the V˙o2difference between resting baseline and steady-state values during contractions was 24.9 ± 1.6 (SE) s in Control and 18.5 ± 1.8 s in Fast O2Delivery (P< 0.05). FasterV˙o2on-kinetics in Fast O2Delivery was associated with an ∼30% reduction in the calculated O2deficit and with less muscle fatigue. During transitions involving contractions at peak V˙o2, convective O2delivery to muscle, together with an inertia of oxidative metabolism, contributes in determining theV˙o2on-kinetics.