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Increase by lysophosphatidylcholines of smooth muscle Ca2+ sensitivity in alpha-toxin-permeabilized small mesenteric artery from the rat

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  • Department of Physiology and Biophysics
  • Center of Magnetic Resonance
  • The Department of Medicine and Nephrology C
1. Pharmacological characterization of different lysophosphatidylcholines was performed based on their effect on the Ca2+ sensitivity of contraction in alpha-toxin-permeabilized rat mesenteric arteries. Furthermore, the effect of noradrenaline on [3H]-myristate-labelled lysophosphatidylcholine levels was assessed, to investigate whether lysophosphatidylcholines could be second messengers. 2. Palmitoyl or myristoyl L-alpha-lysophosphatidylcholine increased the sensitivity to Ca2+, whereas lysophosphatidylcholines containing other fatty acids had less or no effect. 3. L-alpha-phosphatidylcholine, L-alpha-glycerophosphorylcholine, palmitic acid, myristic acid and choline, potential metabolites of lysophosphatidylcholines, did not affect contractions. 4. Noradrenaline (GTP was required) and GTP gamma S increased the sensitivity to Ca2+, and GDP-beta-S inhibited the effect of noradrenaline. Lysophosphatidylcholines, however, had no requirement for GTP and caused sensitization in the presence of GDP-beta-S. 5. Calphostin C, a relatively specific protein kinase C inhibitor, did not affect contraction induced by Ca2+, but abolished the sensitizing effect of lysophosphatidylcholine. 6. Noradrenaline caused no measurable changes in the levels of [3H]-myristate-labelled phosphatidylcholine and lysophosphatidylcholine at 30 s and 5 min stimulation. 7. These results suggest that lysophosphatidylcholines can increase Ca2+ sensitivity through a G-protein-independent, but a protein kinase C-dependent mechanism. However, the role for lysophosphatidylcholines as messengers causing Ca2+ sensitization during stimulation with noradrenaline remains uncertain because no increase in [3H]-myristate labelled lysophosphatidylcholine could be measured during noradrenaline stimulation.
Original languageEnglish
JournalBritish Journal of Pharmacology
Pages (from-to)1238-1244
Number of pages7
Publication statusPublished - 1 Mar 1996

    Research areas

  • Animals, Calcium, Dose-Response Relationship, Drug, Lysophosphatidylcholines, Male, Mesenteric Arteries, Muscle Contraction, Muscle, Smooth, Vascular, Naphthalenes, Norepinephrine, Protein Kinase C, Rats, Rats, Wistar, Type C Phospholipases

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