Lash J M, Bohlen H G
Am J Physiol. 1987 Jun;252(6 Pt 2):H1192-202. doi: 10.1152/ajpheart.1987.252.6.H1192.
This study evaluated the possibility that during skeletal muscle contractions tissue O2 tension (Po2) around arterioles and venules decreases substantially more than in the middle of the capillary bed and thereby influences functional hyperemia. Periarteriolar [H+] and [K+] were also measured because most large arterioles are in close proximity to venules such that the biochemical status of the periarteriolar tissue could be influenced by a large decrease in O2 availability in the annulet of tissue surrounding the venules. Stimulation frequencies in the range of 2-12 Hz were used to activate the rat spinotrapezius muscle. Periarteriolar and capillary bed Po2, [H+], and [K+] changed during the first few minutes of stimulation but were restored to near resting concentrations as the functional hyperemia developed. However, perivenular Po2 decreased rapidly to approximately 50-60% of the resting gas tension as contractions began, and only minor recovery occurred. Elevation of tissue and periarteriolar Po2 with an O2-enriched superfusion solution did not prevent dilation during contractions to the same diameter as during the response at very low superfusion Po2. Therefore, the extent to which O2 influences arteriolar dilation and exercise hyperemia in the spinotrapezius muscle of the rat may depend less on periarteriolar and capillary bed Po2 than on the release of vasoactive materials from the nearby perivenular tissues as the availability of O2 decreases.
本研究评估了一种可能性，即在骨骼肌收缩期间，小动脉和小静脉周围的组织氧张力（Po2）下降幅度比毛细血管床中部大得多，从而影响功能性充血。还测量了小动脉周围的[H+]和[K+]，因为大多数大动脉与小静脉紧密相邻，以至于小动脉周围组织的生化状态可能会受到小静脉周围组织环中氧供应大幅减少的影响。使用2-12Hz范围内的刺激频率来激活大鼠的斜方肌。在刺激的最初几分钟内，小动脉周围和毛细血管床的Po2、[H+]和[K+]发生了变化，但随着功能性充血的发展，它们恢复到接近静息浓度。然而，随着收缩开始，小静脉周围的Po2迅速下降至静息气体张力的约50-60%，仅出现轻微恢复。用富氧灌注液提高组织和小动脉周围的Po2并不能防止收缩期间的血管扩张，扩张程度与在非常低的灌注Po2下的反应时相同。因此，氧对大鼠斜方肌中小动脉扩张和运动性充血的影响程度，可能与其对小动脉周围和毛细血管床Po2的依赖程度相比，更多地取决于随着氧供应减少，附近小静脉周围组织中血管活性物质的释放。
