Analytical studies of spontaneous and vasopressin-induced calcium oscillations in cultured vascular smooth muscle cells

Sheng-Nan Wu, Hsin Su Yu, Yousuke Seyama

Research output: Contribution to journalArticle

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Abstract

Spontaneous and vasopressin-induced Ca2+ oscillations in cultured vascular smooth muscle (A7r5) cells were further examined and characterized. Intracellular Ca2+ concentrations ([Ca2+](i)) were measured by use of a high-performance laser cytometer. When the oscillatory patterns in [Ca2+](i) were analyzed with a power spectrum method, about 80% of cells exhibited spontaneous Ca2+ oscillations with the frequency of 0.02-0.5 Hz. Nifedipine abolished these repetitive spikes, whereas pinacidil partially attenuated their amplitude and frequency. When vasopressin (100 nM) was applied to A7r5 cells, there was an initial rise in [Ca2+](i), followed by a delayed sustained increase in [Ca2+](i). The one-pool, nonoscillatory model was employed to fit this biphasic change, and the difference between the observed response and the simulated response was then analyzed with a power spectral method. About 50% of cells were noted to display oscillatory patterns in [Ca2+](i) after sustained increase in [Ca2+](i). The present study indicates that spontaneous Ca2+ oscillations in A7r5 cells are modulated by the activity of ATP-sensitive K+ channels and are not related to pertussis toxin-sensitive GTP-binding protein(s). On the basis of the one-pool, nonoscillatory model, it is suggested that the buffering capacity of internal stores appears to be stronger in the cells with spontaneous Ca2+ oscillations than in those in a quiescent state, and the vasopressin-mediated inhibition of accumulation by internal stores was attenuated when the cells exhibited spontaneous Ca2+ oscillations. The implementation of this minimum kinetic model integrated with a power spectrum method would be an alternative to understand the oscillating behavior in [Ca2+](i).

Original languageEnglish
Pages (from-to)42-48
Number of pages7
JournalJournal of biochemistry
Volume119
Issue number1
DOIs
Publication statusPublished - 1996 Jan 1

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Calcium Signaling
Vasopressins
Vascular Smooth Muscle
Smooth Muscle Myocytes
Muscle
Cells
Power spectrum
Calcium
Pinacidil
Pertussis Toxin
Nifedipine
GTP-Binding Proteins
Adenosine Triphosphate
Kinetics
Lasers

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology

Cite this

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title = "Analytical studies of spontaneous and vasopressin-induced calcium oscillations in cultured vascular smooth muscle cells",
abstract = "Spontaneous and vasopressin-induced Ca2+ oscillations in cultured vascular smooth muscle (A7r5) cells were further examined and characterized. Intracellular Ca2+ concentrations ([Ca2+](i)) were measured by use of a high-performance laser cytometer. When the oscillatory patterns in [Ca2+](i) were analyzed with a power spectrum method, about 80{\%} of cells exhibited spontaneous Ca2+ oscillations with the frequency of 0.02-0.5 Hz. Nifedipine abolished these repetitive spikes, whereas pinacidil partially attenuated their amplitude and frequency. When vasopressin (100 nM) was applied to A7r5 cells, there was an initial rise in [Ca2+](i), followed by a delayed sustained increase in [Ca2+](i). The one-pool, nonoscillatory model was employed to fit this biphasic change, and the difference between the observed response and the simulated response was then analyzed with a power spectral method. About 50{\%} of cells were noted to display oscillatory patterns in [Ca2+](i) after sustained increase in [Ca2+](i). The present study indicates that spontaneous Ca2+ oscillations in A7r5 cells are modulated by the activity of ATP-sensitive K+ channels and are not related to pertussis toxin-sensitive GTP-binding protein(s). On the basis of the one-pool, nonoscillatory model, it is suggested that the buffering capacity of internal stores appears to be stronger in the cells with spontaneous Ca2+ oscillations than in those in a quiescent state, and the vasopressin-mediated inhibition of accumulation by internal stores was attenuated when the cells exhibited spontaneous Ca2+ oscillations. The implementation of this minimum kinetic model integrated with a power spectrum method would be an alternative to understand the oscillating behavior in [Ca2+](i).",
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Analytical studies of spontaneous and vasopressin-induced calcium oscillations in cultured vascular smooth muscle cells. / Wu, Sheng-Nan; Yu, Hsin Su; Seyama, Yousuke.

In: Journal of biochemistry, Vol. 119, No. 1, 01.01.1996, p. 42-48.

Research output: Contribution to journalArticle

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