Confocal laser scanning microscopy and fluo 4 were used to visualize local and whole Cell Ca2+ transients within individual smooth muscle cells (SMC) of intact, pressurized rat mesenteric small arteries during activation of α1-adrenoceptors. A method was developed to record the Ca2+ transients within individual SMC during the changes in arterial diameter. Three distinct types of "Ca2+ signals" were influenced by adrenergic activation (agonist: Phenylephrine). First, asynchronous Ca2+ 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 Ca2+ transients, not reported previously, occurred at higher levels of adrenergic stimulation and continued for long periods during oscillatory vasomotion. Finally, Ca2+ sparks slowly decreased in frequency of occurrence during exposure to adrenergic agonists. Thus adrenergic activation causes a decrease in the frequency of Ca2+ sparks and an increase in the frequency of asynchronous wavelike Ca2+ transients, both of which should tend to decrease arterial diameter. Oscillatory vasomotion is associated with spatially uniform synchronous oscillations of cellular [Ca2+] and may have a different mechanism than the asynchronous, propagating Ca2+ transients.
|Journal||American Journal of Physiology - Heart and Circulatory Physiology|
|Issue number||5 49-5|
|State||Published - May 1 2001|
- Calcium transient
- Mesenteric artery
- Smooth muscle
- Smooth muscle cells