Abstract
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.
Original language | English |
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Pages (from-to) | H2399-H2405 |
Journal | American Journal of Physiology - Heart and Circulatory Physiology |
Volume | 280 |
Issue number | 5 49-5 |
DOIs | |
State | Published - May 2001 |
Keywords
- Artery
- Calcium transient
- Mesenteric artery
- Smooth muscle
- Smooth muscle cells