Mauban J R, Lamont C, Balke C W, Wier W G
Department of Physiology and Division of Cardiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201, USA.
Am J Physiol Heart Circ Physiol. 2001 May;280(5):H2399-405. doi: 10.1152/ajpheart.2001.280.5.H2399.
Confocal laser scanning microscopy and fluo 4 were used to visualize local and whole cell Ca(2+) transients within individual smooth muscle cells (SMC) of intact, pressurized rat mesenteric small arteries during activation of alpha1-adrenoceptors. A method was developed to record the Ca(2+) transients within individual SMC during the changes in arterial diameter. Three distinct types of "Ca(2+) signals" were influenced by adrenergic activation (agonist: phenylephrine). First, asynchronous Ca(2+) transients were elicited by low levels of adrenergic stimulation. These propagated from a point of origin and then filled the cell. Second, synchronous, spatially uniform Ca(2+) transients, not reported previously, occurred at higher levels of adrenergic stimulation and continued for long periods during oscillatory vasomotion. Finally, Ca(2+) sparks slowly decreased in frequency of occurrence during exposure to adrenergic agonists. Thus adrenergic activation causes a decrease in the frequency of Ca(2+) sparks and an increase in the frequency of asynchronous wavelike Ca(2+) transients, both of which should tend to decrease arterial diameter. Oscillatory vasomotion is associated with spatially uniform synchronous oscillations of cellular [Ca(2+)] and may have a different mechanism than the asynchronous, propagating Ca(2+) transients.
利用共聚焦激光扫描显微镜和Fluo 4来观察完整的、处于压力状态的大鼠肠系膜小动脉单个平滑肌细胞（SMC）内局部和全细胞的Ca(2+)瞬变，此时α1-肾上腺素能受体被激活。开发了一种方法来记录动脉直径变化期间单个SMC内的Ca(2+)瞬变。三种不同类型的“Ca(2+)信号”受肾上腺素能激活（激动剂：去氧肾上腺素）影响。首先，低水平的肾上腺素能刺激引发异步Ca(2+)瞬变。这些瞬变从一个起源点开始传播，然后充满整个细胞。其次，同步的、空间上均匀的Ca(2+)瞬变（此前未报道过）在较高水平的肾上腺素能刺激下出现，并在振荡性血管运动期间持续很长时间。最后，在暴露于肾上腺素能激动剂期间，Ca(2+)火花的出现频率缓慢下降。因此，肾上腺素能激活导致Ca(2+)火花频率降低，异步波状Ca(2+)瞬变频率增加，这两者都应倾向于使动脉直径减小。振荡性血管运动与细胞内[Ca(2+)]的空间均匀同步振荡有关，其机制可能与异步传播的Ca(2+)瞬变不同。
