Adrenergic stimulation of rat resistance arteries affects Ca(2+) sparks, Ca(2+) waves, and Ca(2+) oscillations.
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.
Mauban
J R
JR
Department of Physiology and Division of Cardiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201, USA.
Lamont
C
C
Balke
C W
CW
Wier
W G
WG
D000818:Animals; D001831:Body Temperature; D002118:Calcium / Q000378:metabolism*; D008297:Male; D008638:Mesenteric Arteries / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D018047:Receptors, Purinergic P1; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D002118:Calcium