Evidence for a tyrosine kinase-dependent activation of the adenylyl Cyclase/PKA cascade downstream from the G-protein-linked endothelin ETA receptor in vascular smooth muscle

Biochem Biophys Res Commun. 1998 Oct 20;251(2):494-500. doi: 10.1006/bbrc.1998.9496.


Endothelin (ET-1), a contractor and mitogen in the vasculature, enhanced cAMP production (t1/2, 2.2 min; EC50, 89 +/- 6.3 nM) and stimulated activity of the cAMP-dependent protein kinase (PKA) in pig coronary arteries. These responses were blunted by the protein tyrosine kinase (PTK) inhibitors genistein and herbimycin-A, but not by inhibitors of protein kinase C or cyclooxygenase. In contrast, forskolin-stimulated cAMP production was unaffected by PTK inhibition. Immunoblot analysis revealed that ET-1 induced a concentration-dependent protein tyrosine (PT) phosphorylation. Sarafotoxin-c, a selective ETB receptor agonist, had no effect on either cAMP levels or PT phosphorylation. Moreover, pervanadate (PV), a potent inhibitor of PT phosphatases, enhanced both cAMP formation and PT phosphorylation, both of which were blocked by PTK inhibitors. The effects of ET-1 and PV were not additive, suggesting a similar mode of activation, whereas responses to ET-1 and forskolin were synergistic. These findings indicate that AC and PKA are activatable via a nonreceptor PTK-dependent pathway downstream from the G-protein-linked ETA receptor. Because cAMP is a dilator and antimitogen in smooth muscle, stimulation of AC activity may be a negative feedback mechanism regulating ET-1-induced vasoconstriction and/or mitogenesis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenylyl Cyclases / metabolism*
  • Animals
  • Benzoquinones
  • Colforsin / pharmacology
  • Coronary Vessels / metabolism
  • Cyclic AMP / metabolism
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Endothelin-1 / pharmacology
  • Endothelin-1 / physiology
  • Enzyme Activation
  • Enzyme Inhibitors / pharmacology
  • GTP-Binding Proteins / metabolism*
  • Genistein / pharmacology
  • In Vitro Techniques
  • Kinetics
  • Lactams, Macrocyclic
  • Muscle, Smooth, Vascular / metabolism*
  • Peptides / pharmacology
  • Protein-Tyrosine Kinases / metabolism*
  • Quinones / pharmacology
  • Receptor, Endothelin A
  • Receptors, Endothelin / drug effects
  • Receptors, Endothelin / physiology*
  • Rifabutin / analogs & derivatives
  • Signal Transduction
  • Swine
  • Vanadates / pharmacology
  • Viper Venoms / pharmacology


  • Benzoquinones
  • Endothelin-1
  • Enzyme Inhibitors
  • Lactams, Macrocyclic
  • Peptides
  • Quinones
  • Receptor, Endothelin A
  • Receptors, Endothelin
  • Viper Venoms
  • pervanadate
  • sarafotoxin-c
  • Colforsin
  • Rifabutin
  • Vanadates
  • herbimycin
  • Genistein
  • Cyclic AMP
  • Protein-Tyrosine Kinases
  • Cyclic AMP-Dependent Protein Kinases
  • GTP-Binding Proteins
  • Adenylyl Cyclases