Harvey Ronee E, Barnes Jill N, Charkoudian Nisha, Curry Timothy B, Eisenach John H, Hart Emma C, Joyner Michael J
Mayo Clinic College of Medicine, Rochester, Minnesota.
Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota.
Physiol Rep. 2014 Jun 6;2(6). doi: 10.14814/phy2.12032. Print 2014 Jun 1.
Beta-adrenergic vasodilator responses may be blunted in humans who are at an increased risk for hypertension. Because menopause is associated with an increase in blood pressure, we tested the hypothesis that forearm blood flow responses to the β-adrenergic receptor agonist isoproterenol are blunted in older, postmenopausal women compared to young, premenopausal women. We used venous occlusion plethysmography to measure forearm blood flow in young premenopausal (26 ± 1 years; n = 13) and postmenopausal (61 ± 2 years; n = 12) women. Forearm blood flow and mean arterial pressure were measured at baseline and during isoproterenol infusion at 1.0, 3.0, 6.0, and 12.0 ng/100 mL tissue/min. The two groups did not differ in body mass index or mean arterial pressure. Baseline forearm blood flow was similar between young and postmenopausal women (3.7 ± 0.5 vs. 2.9 ± 0.4 mL/100 mL tissue/min, respectively; P > 0.05). At the lowest dose of isoproterenol, forearm blood flow vasodilator responses were lower in postmenopausal women compared with young women (5.8 ± 0.4 vs. 7.4 ± 0.3 mL/100 mL tissue/min, respectively; P < 0.05). Thereafter, forearm blood flow remained similar between the groups for the remaining isoproterenol doses. In conclusion, β-adrenergic receptor-mediated forearm vasodilator responses are blunted in healthy, older postmenopausal women at lower but not higher doses of isoproterenol. This suggests that in aging women, β-adrenergic receptor-mediated vasodilator responses may be blunted at a moderate level of stimulation while maximum receptor responses are preserved.
在高血压风险增加的人群中，β-肾上腺素能血管舒张反应可能会减弱。由于绝经与血压升高有关，我们检验了这样一个假设：与年轻的绝经前女性相比，年长的绝经后女性对β-肾上腺素能受体激动剂异丙肾上腺素的前臂血流反应会减弱。我们使用静脉阻塞体积描记法测量了年轻绝经前（26±1岁；n = 13）和绝经后（61±2岁；n = 12）女性的前臂血流。在基线时以及在以1.0、3.0、6.0和12.0 ng/100 mL组织/分钟的速度输注异丙肾上腺素期间，测量前臂血流和平均动脉压。两组在体重指数或平均动脉压方面没有差异。年轻女性和绝经后女性的基线前臂血流相似（分别为3.7±0.5与2.9±0.4 mL/100 mL组织/分钟；P>0.05）。在最低剂量的异丙肾上腺素时，绝经后女性的前臂血流舒张反应低于年轻女性（分别为5.8±0.4与7.4±0.3 mL/100 mL组织/分钟；P<0.05）。此后，在其余异丙肾上腺素剂量下，两组之间的前臂血流保持相似。总之，在健康的年长绝经后女性中，低剂量而非高剂量的异丙肾上腺素会使β-肾上腺素能受体介导的前臂血管舒张反应减弱。这表明，在老年女性中，β-肾上腺素能受体介导的血管舒张反应在中等刺激水平时可能会减弱，而最大受体反应则得以保留。
