Involvement of both G protein alphas and beta gamma subunits in beta-adrenergic stimulation of vascular L-type Ca(2+) channels

Br J Pharmacol. 2001 Feb;132(3):669-76. doi: 10.1038/sj.bjp.0703864.


1. Previous data have shown that activation of beta(3)-adrenoceptors stimulates vascular L-type Ca(2+) channels through a G alphas-induced stimulation of the cyclic AMP/PKA pathway. The present study investigated whether beta-adrenergic stimulation also uses the G beta gamma/PI3K/PKC pathway to modulate L-type Ca(2+) channels in rat portal vein myocytes. 2. Peak Ba(2+) current (I(Ba)) measured using the whole-cell patch clamp method was maximally increased by application of 10 microm isoprenaline after blockade of beta(3)-adrenoceptors by 1 microM SR59230A. Under these conditions, the isoprenaline-induced stimulation of I(Ba) was reversed by ICI-118551 (a specific beta(2)-adrenoceptor antagonist) but not by atenolol (a specific beta(1)-adrenoceptor antagonist). The beta(2)-adrenoceptor agonist salbutamol increased I(Ba), an effect which was reversed by ICI-118551 whereas the beta(1)-adrenoceptor agonist dobutamine had no effect on I(Ba). 3. Application of PKA inhibitors (H-89 and Rp 8-Br-cyclic AMPs) or a PKC inhibitor (calphostin C) alone did not affect the beta(2)-adrenergic stimulation of I(Ba) whereas simultaneous application of both PKA and PKC inhibitors completely blocked this stimulation. 4. The beta(2)-adrenergic stimulation of L-type Ca(2+) channels was blocked by a pre-treatment with cholera toxin and by intracellular application of an anti-G alphas antibody (directed against the carboxyl terminus of G alphas). In the presence of H-89, intracellular infusion of an anti-Gss(com) antibody or a beta ARK(1) peptide as well as a pre-treatment with wortmannin (a PI3K inhibitor) blocked the beta(2)-adrenergic stimulation of I(Ba). 5. These results suggest that the beta(2)-adrenergic stimulation of vascular L-type Ca(2+) channels involves both G alphas and G beta gamma subunits which exert their stimulatory effects through PKA and PI3K/PKC pathways, respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Channels, L-Type / metabolism*
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Heterotrimeric GTP-Binding Proteins / metabolism*
  • In Vitro Techniques
  • Muscle, Smooth, Vascular / enzymology
  • Muscle, Smooth, Vascular / metabolism*
  • Portal Vein / cytology
  • Portal Vein / metabolism
  • Protein Kinase C / metabolism
  • Rats
  • Receptors, Adrenergic, beta-2 / metabolism*
  • Signal Transduction


  • Calcium Channels, L-Type
  • Receptors, Adrenergic, beta-2
  • Cyclic AMP-Dependent Protein Kinases
  • Protein Kinase C
  • Heterotrimeric GTP-Binding Proteins