McGrath M A, Shepherd J T
Am J Physiol. 1976 Jul;231(1):141-7. doi: 10.1152/ajplegacy.1976.231.1.141.
Helical strips from dogs' saphenous veins were mounted in an organ bath (Krebs-Ringer solution, 37 degrees C) for isometric tension recording. Additional strips were incubated with [7-3H]norepinephrine and mounted for superfusion and isometric tension recording. The perfusate was collected every 2 min for estimation of total radioactivity and for column chromatographic separation of [3H]norepinephrine and its metabolites. Increasing osmolarity by sucrose caused a slow contraction that was maximal at 500-550 mosM and was accompanied by a reduction in total 3H efflux. The contraction was unaffected by a Ca2+-free medium, alpha-adrenegic blockade, and beta-adrenergic stimulaton. It was depressed by cooling (29 degrees C) and by anoxia combined with a glucose-free medium. Contractions elicited by K+ and Ba2+ were augmented by hyperosmolarity, but those caused by sympathetic nerve stimulation, tyramine, and norepinephrine were depressed. The output of [3H]norepinephrine during nerve stimulation was reduced. Thus, the hyperosmolarity causes 1) contraction of vascular smooth muscle, 2) augmentation of the contractile response to K+ and Ba2+, 3) depression of the excitation caused by norepinephrine, and 4) inhibition of the neuronal release of norepinephrine.
将犬大隐静脉的螺旋条带安装在器官浴槽（37℃的克雷布斯 - 林格溶液）中进行等长张力记录。另外的条带用[7 - ³H]去甲肾上腺素孵育后安装用于灌流和等长张力记录。每2分钟收集一次灌流液，用于估计总放射性以及对[³H]去甲肾上腺素及其代谢产物进行柱色谱分离。用蔗糖增加渗透压会引起缓慢收缩，在500 - 550 mosM时达到最大，同时伴随³H总流出量减少。该收缩不受无钙培养基、α - 肾上腺素能阻断和β - 肾上腺素能刺激的影响。冷却（29℃）以及缺氧联合无糖培养基会使其受到抑制。高渗会增强由K⁺和Ba²⁺引起的收缩，但会抑制由交感神经刺激、酪胺和去甲肾上腺素引起的收缩。神经刺激期间[³H]去甲肾上腺素的释放量减少。因此，高渗会导致：1）血管平滑肌收缩；2）增强对K⁺和Ba²⁺的收缩反应；3）抑制去甲肾上腺素引起的兴奋；4）抑制去甲肾上腺素的神经元释放。
