The Journal of Membrane Biology

, Volume 59, Issue 1, pp 19–25

Evidence for two separate Ca2+ pathways in smooth muscle plasmalemma

  • Kaushik D. Meisheri
  • O. Hwang
  • Cornelis van Breemen
Articles

DOI: 10.1007/BF01870817

Cite this article as:
Meisheri, K.D., Hwang, O. & van Breemen, C. J. Membrain Biol. (1981) 59: 19. doi:10.1007/BF01870817

Summary

The activation of rabbit aortic smooth muscle was studied by two most widely used vascular smooth muscle stimulants: α-adrenoceptor activation by norepinephrine (NE) and high-K+ depolarization. This was studied by measurements of isometric contractions and net as well as unidirectional Ca2+ fluxes. These parameters showed markedly differential sensitivities towards two smooth muscle inhibitors used in this study: D 600 and amrinone. By choosing an appropriate concentration of D 600 or amrinone, Ca2+ uptake or Ca2+ influx induced by high K+ or NE could be selectively inhibited. Furthermore, by using unidirectional flux measurements it was demonstrated that Ca2+ influx stimulated by NE and high K+ were additive in nature. The data from the addivity experiment exclude the interpretation of a common Ca2+ pathway with two separate mechanisms for opening it. The data on three criteria employed in this study provide evidence for the existence of two independent Ca2+ pathways, one for each mode of activation, for Ca2+ influx known to be associated with these contractions.

Copyright information

© Springer-Verlag New York Inc 1981

Authors and Affiliations

  • Kaushik D. Meisheri
    • 1
  • O. Hwang
    • 1
  • Cornelis van Breemen
    • 1
  1. 1.Department of PharmacologyUniversity of Miami School of MedicineMiami