These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Stimulation-induced regional alteration of Ca2+ levels in single arterial smooth muscle cells.
    Author: Goldman WF, Blaustein MP.
    Journal: J Cardiovasc Pharmacol; 1988; 12 Suppl 5():S13-9. PubMed ID: 2469871.
    Abstract:
    Contraction in vascular smooth muscle is normally triggered by an increase in the cytosolic free Ca2+ concentration. We employed the fluorescent Ca indicator, fura-2, and digital imaging microscopy to study the spatial distribution of intracellular Ca2+ in arterial myocytes and the changes elicited by norepinephrine (NE) and by alterations in the Na+ electrochemical gradient. In modified Kreb's solution containing 1.8 mM Ca2+, these bovine tail artery myocytes were relaxed and able to maintain normal membrane potentials. The cells contracted rapidly when exposed to NE or high K+ solution. They then relaxed slowly when the activator was washed away. A rise in Ca2+ concentration, [Ca2+], was elicited by NE as well as by Ca2+ entry via Na+/Ca2+ exchange. Digital analysis of images of cellular fura-2 fluorescence revealed that the intracellular [Ca2+] was relatively uniformly distributed in resting cells prior to activation. During NE-evoked contractions, intracellular [Ca2+] increased an average of two- to threefold, and the distribution of [Ca2+] became much more heterogeneous. Upon recovery from activation, the cells relaxed, usually attaining greater than 90% of their original resting length. In contrast to the relatively uniform Ca2+ distribution observed prior to NE activation, discrete regions of elevated [Ca2+] were observed throughout the recovered cells. Similarly, reducing the Na+ electrochemical gradient and, presumably, activating Na+/Ca2+ exchange elicited a rise in [Ca2+]. In cells exposed to increased [Na+]i and reduced [Na+]o, as in cells following recovery from NE stimulation, discrete areas of high [Ca2+] were apparent. The large spatial variation induced by cell activation implies that Ca2+ was sequestered at localized sites throughout the cell.
    [Abstract] [Full Text] [Related] [New Search]