Heart and Circulatory Physiology

Adrenergic stimulation of rat resistance arteries affects Ca2+ sparks, Ca2+ waves, and Ca2+oscillations

Joseph R. H. Mauban, Christine Lamont, C. William Balke, W. Gil Wier


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.

  • calcium transient
  • smooth muscle
  • artery
  • mesenteric artery
  • smooth muscle cells


  • This study was supported by National Institutes of Health Research Grant HL-60748 (to W. G. Wier) and by Training Grant AR-07592 to the University of Maryland Training Program in Muscle Biology.

  • Address for reprint requests and other correspondence: W. G. Wier, Dept. of Physiology, Univ. of Maryland, Baltimore, 655 West Baltimore St., Baltimore, MD 21201 (E-mail: gwier001{at}umaryland.edu).

  • The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

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