Lash J M, Shoukas A A
Department of Biomedical Engineering, Johns Hopkins Medical School, Baltimore, Maryland 21205.
J Appl Physiol (1985). 1991 Jun;70(6):2551-8. doi: 10.1152/jappl.1991.70.6.2551.
To determine whether microvessels in resting or contracting skeletal muscle constrict during baroreceptor activation, vascular diameters were measured in the spinotrapezius muscle of adult rats (n = 12) during occlusion of the common carotid arteries. Neural and myogenic components were distinguished using two types of occlusion: 1) "normal" (arterial pressure was allowed to increase with baroreceptor activation) and 2) "isobaric" (arterial pressure was maintained constant by decreasing blood volume). During normal occlusions, intermediate and small arteriolar diameters decreased in resting and contracting muscle (10-15% and 25-30%, respectively). Large arterioles and all-sized venules distended slightly (approximately 5%) in resting muscle, but diameters were maintained or decreased in contracting muscle. When arterial pressure was maintained constant (isobaric), the microvascular responses to baroreceptor activation in both resting and contracting muscle were essentially eliminated. We conclude that nearly all the arteriolar constriction observed in the spinotrapezius muscle during normal carotid artery occlusion is myogenic in origin, secondary to increased arterial pressure. This pressure-dependent constriction is augmented during skeletal muscle contraction and functional vasodilation.
为了确定在压力感受器激活期间，静息或收缩骨骼肌中的微血管是否会收缩，在成年大鼠（n = 12）的斜方肌中测量了颈总动脉闭塞期间的血管直径。使用两种类型的闭塞来区分神经和肌源性成分：1）“正常”（允许动脉压随着压力感受器激活而升高）和2）“等压”（通过减少血容量维持动脉压恒定）。在正常闭塞期间，静息和收缩肌肉中的中小动脉直径减小（分别为10 - 15%和25 - 30%）。大的小动脉和各种大小的小静脉在静息肌肉中略有扩张（约5%），但在收缩肌肉中直径维持不变或减小。当动脉压维持恒定时（等压），静息和收缩肌肉中对压力感受器激活的微血管反应基本消除。我们得出结论，在正常颈动脉闭塞期间，斜方肌中观察到的几乎所有小动脉收缩起源于肌源性，继发于动脉压升高。这种压力依赖性收缩在骨骼肌收缩和功能性血管舒张期间增强。
