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GTPγS Activates Calcium Channels in Neonatal Rat Ventricular Cells

  • Q. Y. Liu
  • E. Karpinski
  • C. G. Benishin
  • P. K. T. Pang
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 311)

Abstract

It has been reported that G proteins modulate voltage-dependent Ca2+ channels in cardiac muscle. G proteins may activate channels directly (acting on Ca2+ channel proteins) or indirectly (acting through intracellular second messengers, e.g., cAMP) (Brown, 1990). The effect of the G protein activator, GTPγS, on Ca2+ channels in neonatal rat ventricular cells has not been demonstrated. Therefore, the effect of the intracellular application of GTPγS, a non-hydrolyzable analogue of GTP, on Ca2+ channel currents in neonatal rat ventricular cells was investigated. Two types of Ca2+ channels have been described in the cardiac cells (Bean, 1985). One type of Ca2+ channel activates at a low threshold and inactivates very rapidly. This channel is called the low voltage-activated or transient channel (L channel). The other type of Ca2+ channel requires larger depolarization for activation and inactivates slowly. This channel is called the high voltage-activated or long-lasting channel (L channel). Therefore, two protocols were used in this study. In one protocol, cells were held at a membrane potential of -80 mV. Test pulses from this holding potential to more positive potentials evoked inward Ca2+ currents which consisted of two components (T and L channel components).

Keywords

Channel Current Test Pulse Ventricular Cell Activate Calcium Channel Transient Channel 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

References

  1. Brown, A.M., Yatani, A., Van Dongen, A.M.J., Kirsch, G.E., Codina, J. and Birnbaumer, L. Networking ionic channels by G proteins. Soc. Gen. Physiol. Ser. 43, 1–9, 1990.Google Scholar
  2. Bean, B.P. Two kinds of calcium channels in canine atrial cells. Differences in kinetics, selectivity and pharmacology. J. Gen. Physiol. 86, 1–30, 1985.PubMedCrossRefGoogle Scholar
  3. Wang, R., Karpinski, E. and Pang, P.K.T. Two types of vol tage-dependent calcium channel currents and their modulation by parathyroid hormone in neonatal rat ventricular cells. J. Cardiovasc. Pharmacol. 17, 990–998, 1990.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1992

Authors and Affiliations

  • Q. Y. Liu
    • 1
  • E. Karpinski
    • 1
  • C. G. Benishin
    • 1
  • P. K. T. Pang
    • 1
  1. 1.Department of PhysiologyUniversity of AlbertaEdmontonCanada

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