scholarly journals Evidence for receptor-mediated bivalent-cation entry in A10 vascular smooth-muscle cells

1990 ◽  
Vol 267 (1) ◽  
pp. 277-280 ◽  
Author(s):  
A W M Simpson ◽  
A Stampfl ◽  
C C Ashley
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Bivalent Cation ◽  
Fura 2 ◽  
Transient Rise

In fura-2-loaded A10 vascular smooth-muscle cells, 1 nM-vasopressin and 200 nM-endothelin evoked a rapid transient rise in intracellular free Ca2+ concentration [(Ca2+]i), which was then followed by a maintained elevation of [Ca2+]i. The maintained elevation of [Ca2+]i was only partially inhibited by 5 microM-nifedipine, but completely abolished in the presence of 1 mM-EGTA. When extracellular Ca2+ was replaced with 1 mM-Mn2+ (Mn2+ quenches fura-2 fluorescence), both endothelin and vasopressin evoked an Mn2+ quench of the fluorescence from the intracellularly trapped fura-2, even in the presence of 5 microM-nifedipine. These data suggest that both vasopressin and endothelin promote a bivalent-cation influx and provide further evidence for receptor-mediated Ca2+ entry in vascular smooth muscle.

Stretch-induced increases in intracellular calcium of isolated vascular smooth muscle cells

1992 ◽  
Vol 263 (4) ◽  
pp. H1292-H1299 ◽  
Author(s):  
M. J. Davis ◽  
G. A. Meininger ◽  
D. C. Zawieja
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Intracellular Calcium ◽  
Vascular Smooth Muscle Cells ◽  
Physiological Saline ◽  
Muscle Cells ◽  
Patch Type ◽  
Fura 2 ◽  
Cell Stretch

Vascular smooth muscle responds to stretch with an increase in active force development. To investigate the role of Ca2+ in this response, we used the fluorescent dye fura-2 to quantitate changes in cytosolic Ca2+ in single, vascular smooth muscle cells during rapid stretch. Cells were enzymatically dispersed from pig coronary arteries, loaded with fura-2/AM, and studied using a digital-imaging microscope. Stretch of individual cells was accomplished by attachment with suction to two patch-type micropipettes to apply force to the ends of the cell. Stretch induced the release of Ca2+ from intracellular stores as well Ca2+ influx across the plasma membrane. In physiological saline solution containing 1.5 mM Ca2+, intracellular calcium increased with cell stretch in a sigmoidal fashion. This relationship was shifted upward in 10 mM Ca2+ bath solution and abolished after several minutes in Ca(2+)-free solution. The dihydropyridine Ca2+ channel blocker nifedipine, in doses sufficient to completely block inward Ca2+ current, produced only a partial block of the sustained stretch-induced intracellular Ca2+ response. It is concluded that in isolated pig coronary arterial smooth muscle cells, stretch-induced Ca2+ influx occurs in part via a nifedipine-resistant pathway, which may be a stretch-activated cation channel.

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