Choate J K, Kato K, Mohan R M
University Laboratory of Physiology, University of Oxford, Parks Road, Oxford OX1 3PT, UK.
Exp Physiol. 2000 Jan;85(1):103-8.
The effects of exercise training were investigated on the vascular responses in the isolated guinea-pig saphenous artery. Exercising animals swam 5 days week-1 for 6 weeks (60 min day-1 for weeks 1 and 2; 75 min day-1 for weeks 3 and 4; 90 min day-1 for weeks 5 and 6), while control animals were placed into shallow water for the same duration. Trained animals had significantly higher ventricular:body weight ratios, increased citrate synthase activity in the latissimus dorsi, and enhanced Na+ pump concentrations in the latissimus dorsi and gastrocnemius muscles (P < 0.05). In vitro isometric techniques were used to measure constriction and relaxation responses of saphenous artery rings from trained and control animals. There were no significant differences in the constriction responses to KCl (50 mm) and phenylephrine (0.3-100 microM) in arterial rings from control versus trained animals. Relaxation responses to acetylcholine (10 microM; ACh-relaxation), following preconstriction with phenylephrine (10 microM), were significantly enhanced in rings from trained animals (P < 0.05). Acetylcholine relaxed the vessels to 47 +/- 6% (control) and 18 +/- 3% (trained) of the preconstriction responses to phenylephrine. The nitric oxide synthase inhibitor N G-nitro-L-arginine (L-NA; 50 microM) significantly attenuated the ACh-relaxation in control and trained animals (P < 0.05). The effect of L-NA on the ACh-relaxation was significantly larger in trained (change in ACh-relaxation with L-NA = 29 +/- 9%) than control (14 +/- 3%) animals (P < 0.05). In conclusion, exercise training enhanced the ACh-relaxation of the isolated guinea-pig saphenous artery. Inhibition of nitric oxide synthase attenuated the ACh-relaxation of rings from control and trained animals, but this effect was significantly larger in the vessels from trained animals. These results are consistent with the idea that nitric oxide could contribute to the enhanced ACh-relaxation of the saphenous artery with exercise training.
研究了运动训练对豚鼠离体隐动脉血管反应的影响。运动组动物每周游泳5天，持续6周（第1周和第2周每天游泳60分钟；第3周和第4周每天游泳75分钟；第5周和第6周每天游泳90分钟），而对照组动物在浅水中放置相同的时间。训练组动物的心室与体重比显著更高，背阔肌中的柠檬酸合酶活性增加，背阔肌和腓肠肌中的钠泵浓度增强（P<0.05）。采用体外等长技术测量训练组和对照组动物隐动脉环的收缩和舒张反应。对照组和训练组动物动脉环对氯化钾（50 mmol）和去氧肾上腺素（0.3 - 100 μmol）的收缩反应无显著差异。在预先用去氧肾上腺素（10 μmol）收缩后，训练组动物动脉环对乙酰胆碱（10 μmol；乙酰胆碱舒张）的舒张反应显著增强（P<0.05）。乙酰胆碱使血管舒张至去氧肾上腺素预收缩反应的47±6%（对照组）和18±3%（训练组）。一氧化氮合酶抑制剂N G - 硝基 - L - 精氨酸（L - NA；50 μmol）显著减弱了对照组和训练组动物的乙酰胆碱舒张反应（P<0.05）。L - NA对乙酰胆碱舒张反应的作用在训练组动物（L - NA作用下乙酰胆碱舒张反应的变化 = 29±9%）比对照组动物（14±3%）中显著更大（P<0.05）。总之，运动训练增强了豚鼠离体隐动脉的乙酰胆碱舒张反应。一氧化氮合酶的抑制减弱了对照组和训练组动物动脉环的乙酰胆碱舒张反应，但这种作用在训练组动物的血管中显著更大。这些结果与一氧化氮可能有助于运动训练增强隐动脉乙酰胆碱舒张反应的观点一致。
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