Plasma membrane calcium flux, protein kinase C activation and smooth muscle contraction

J Pharmacol Exp Ther. 1985 Nov;235(2):267-73.

Abstract

Isolated perfused rabbit ear arteries contract when treated with 12-O-tetradecanoylphorbol-13-acetate (TPA), an activator of the calcium-activated, phospholipid-dependent protein kinase or C-kinase. Under conditions where the calcium concentration in the perfusate is 1.5 mM and the potassium concentration is 4.8 mM, there is a latent period of 70 +/- 19 min (mean +/- S.E.M., n = 10) between TPA addition and the onset of the contractile response. Once initiated, the contractile response is progressive and sustained. When perfusion conditions are altered in such a way as to modify calcium flux across the plasma membrane (i.e., raising the extracellular calcium concentration to 2.5 mM Ca++, raising the extracellular potassium concentration to 10 mM, and/or preincubating the tissues in media containing 100 nM Bay K 8644, a potent calcium channel agonist), the latency period between TPA addition and initiation of the contractile response is significantly reduced (2.5 mM Ca++, 37 +/- 7 min; 10 mM K+ and 2.5 mM Ca++, 11 +/- 3 min; 100 nM Bay K 8644 and 1.5 mM Ca++, 20 +/- 7 min; 100 nM Bay K 8644 and 2.5 mM Ca2+, 8.5 +/- 1.7 min; 10 mM K+ and 100 nM Bay K 8644, 11 +/- 5 min). Likewise, the combination of 2.5 mM calcium, 100 nM Bay K 8644, and 3.3 microM ouabain results in a contractile response 4.5 +/- 2.0 min after TPA addition (means +/- S.E.M., n = 4). Control tissues (absence of TPA addition) run simultaneously show no contractile responses to the various Ca++ flux regulators even after 90 min of incubation.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
  • Animals
  • Calcium / metabolism*
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Colforsin / pharmacology
  • Drug Synergism
  • Enzyme Activation
  • Muscle Contraction* / drug effects
  • Muscle, Smooth, Vascular / cytology
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / metabolism*
  • Nifedipine / analogs & derivatives
  • Nifedipine / pharmacology
  • Nitrendipine
  • Ouabain / pharmacology
  • Perfusion
  • Phospholipids / metabolism
  • Potassium / metabolism
  • Protein Kinase C / metabolism*
  • Rabbits
  • Tetradecanoylphorbol Acetate / pharmacology
  • Vasoconstriction

Substances

  • Phospholipids
  • Colforsin
  • Ouabain
  • 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
  • Nitrendipine
  • Protein Kinase C
  • Nifedipine
  • Tetradecanoylphorbol Acetate
  • Potassium
  • Calcium