Maekawa K, Kuboki T, Miyawaki T, Shimada M, Yamashita A, Clark G T
Department of Fixed Prosthodontics, Okayama University Dental School, Japan.
Arch Oral Biol. 1999 Apr;44(4):319-27. doi: 10.1016/s0003-9969(98)00127-7.
This study evaluated the effect of intravenous infusion of a non-selective alpha-adrenergic blocking agent on masseter muscle haemodynamics induced by 4 degrees C cold pressor stimulation (CPS) of the right foot and ankle, which reportedly evokes a rapidly increasing sympathetic nerve activity in human skeletal muscle. Nine healthy non-smoking males (mean age 23.7+/-2.1 year) with no history of chronic muscle pain or migraine participated. The haemoglobin (Hb) concentration in the right masseter was continuously recorded by non-invasive, near-infrared spectroscopy. Heart rate and blood pressure were also recorded. The experiment involved the following sequence: (1) a placebo (physiological saline) with a CPS trial; (2) a 30-sec maximal voluntary clenching (MVC)-only trial; and (3) an alpha-adrenergic blocking agent with a CPS trial. The saline and drug trials each involved continuous recording for 1 min before, 2 min during and 5 min after the CPS. Physiological saline (20 ml) or phentolamine mesylate (20 ml) were infused at the rate of 2 ml/min. This infusion was begun 15 min before baseline recording and participants were not aware which solution (saline or phentolamine) was being infused. For the MVC trial, each participant performed a 30-sec MVC of his jaw-closing muscles followed by a 15-min rest between each trial. The individual Hb data were adjusted so that the baseline at the beginning of the experiment was equal to zero and all data were normalized as a percentage of the individual's highest absolute Hb change seen after the MVC. The mean baseline Hb concentrations 1 min before CPS were significantly higher in the alpha-blocker trial (83.6%) than in the placebo saline trial (P < 0.001). The change in mean Hb concentration from baseline during CPS in the alpha-blocker trial was significantly less than in the placebo trial (P = 0.006). Mean heart rate before CPS was also significantly higher in the alpha-blocker trial (85.2 beats/min) than in the placebo trial (69.6 beats/min) (P < 0.001). There were no significant differences in the mean systolic and diastolic blood pressures between the placebo and alpha-blocker trials in any time period. The results suggest that non-selective alpha-adrenoceptor blockade increases the blood volume in the masseter muscle. This change might be due to a combination of peripheral vasodilation and an increase in cardiac output.
本研究评估了静脉输注非选择性α-肾上腺素能阻滞剂对因右脚和脚踝4℃冷加压刺激（CPS）所诱发的咬肌血流动力学的影响，据报道，这种刺激会引起人体骨骼肌交感神经活动迅速增强。9名无慢性肌肉疼痛或偏头痛病史的健康非吸烟男性（平均年龄23.7±2.1岁）参与了研究。通过无创近红外光谱法持续记录右侧咬肌的血红蛋白（Hb）浓度，同时记录心率和血压。实验按以下顺序进行：（1）安慰剂（生理盐水）加CPS试验；（2）仅30秒最大自主收缩（MVC）试验；（3）α-肾上腺素能阻滞剂加CPS试验。生理盐水和药物试验均包括在CPS前1分钟、期间2分钟和之后5分钟持续记录。以2 ml/min的速率输注生理盐水（20 ml）或甲磺酸酚妥拉明（20 ml）。在基线记录前15分钟开始输注，参与者不知道输注的是哪种溶液（生理盐水或酚妥拉明）。对于MVC试验，每位参与者对其闭口肌进行30秒的MVC，每次试验之间休息15分钟。对个体Hb数据进行调整，使实验开始时的基线等于零，所有数据均以个体在MVC后出现的最高绝对Hb变化的百分比进行归一化。α-阻滞剂试验中CPS前1分钟的平均基线Hb浓度（83.6%）显著高于安慰剂生理盐水试验（P<0.001）。α-阻滞剂试验中CPS期间Hb浓度相对于基线的变化显著小于安慰剂试验（P = 0.006）。α-阻滞剂试验中CPS前的平均心率（85.2次/分钟）也显著高于安慰剂试验（69.6次/分钟）（P<0.001）。在任何时间段，安慰剂试验和α-阻滞剂试验之间的平均收缩压和舒张压均无显著差异。结果表明，非选择性α-肾上腺素能受体阻滞可增加咬肌的血容量。这种变化可能是外周血管舒张和心输出量增加共同作用的结果。
