Journal article
β-Adrenergic inhibition of AGEPC-stimulated Na+/Ca2+ exchange and AGEPC-induced platelet activation
Biochimica et biophysica acta. Molecular cell research, Vol.1014(2), pp.195-202
1989
DOI: 10.1016/0167-4889(89)90034-7
PMID: 2554977
Abstract
Recently, AGEPC (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) was found to initiate contraction of ileal smooth muscle strips and to enhance Na+/Ca2+ exchange in ileal plasmalemmal vesicles. In the present study, the effects of the smooth muscle relaxant, isoproterenol, on Na+/Ca2+ exchange in rat ileal plasmalemmal vesicles was examined. In this preparation, Na+/Ca2+ exchange was stimulated 131 +/- 8% and 264 +/- 19% by addition of 50 nM and 100 nM AGEPC, respectively. Isoproterenol, a beta-adrenergic agonist, inhibited AGEPC stimulation of Na+/Ca2+ exchange in a dose- and time-dependent manner but had no effect on basal rates of Na+/Ca2+ antiport. At 1 microM, isoproterenol inhibited 86% of the Na+/Ca2+ exchange stimulated by 50 nM AGEPC. Vesicular cAMP levels were increased over 100% following the addition of 1 microM isoproterenol for 30 s. Inhibition of AGEPC-stimulated vesicular Na+/Ca2+ exchange and elevation of vesicular cAMP levels by isoproterenol was prevented by the beta-receptor antagonist propranolol (5 microM), demonstrating that these effects of isoproterenol were mediated by interaction with vesicular beta-adrenergic receptors. Additional studies with washed rabbit platelets demonstrated that isoproterenol inhibited AGEPC-induced aggregation and serotonin release. These effects of isoproterenol were dose- and time-dependent and were antagonized by propranolol. Isoproterenol had no effect on thrombin-induced aggregation and did not change appreciably platelet cAMP levels. Moreover, dibutyryl cAMP could not mimic the effect of isoproterenol to inhibit an AGEPC-induced aggregation. On a molar basis, the inhibitory effects of isoproterenol toward AGEPC action were greater in the ileal preparation than in the platelets. It is suggested that beta-adrenergic agonists may modulate AGEPC-induced ileal Na+/Ca2+ exchange and AGEPC-induced platelet aggregation through cAMP-dependent and-independent mechanisms, respectively.
Details
- Title: Subtitle
- β-Adrenergic inhibition of AGEPC-stimulated Na+/Ca2+ exchange and AGEPC-induced platelet activation
- Creators
- Mark Kester - Univ. Texas health sci. cent., dep. biochemistry, San Antonio TX, United StatesRory A Fisher - Univ. Texas health sci. cent., dep. biochemistry, San Antonio TX, United StatesMerle S Olson - Univ. Texas health sci. cent., dep. biochemistry, San Antonio TX, United States
- Resource Type
- Journal article
- Publication Details
- Biochimica et biophysica acta. Molecular cell research, Vol.1014(2), pp.195-202
- Publisher
- Elsevier; Amsterdam
- DOI
- 10.1016/0167-4889(89)90034-7
- PMID
- 2554977
- ISSN
- 0167-4889
- eISSN
- 1879-2596
- Language
- English
- Date published
- 1989
- Academic Unit
- Iowa Neuroscience Institute; Neuroscience and Pharmacology; Internal Medicine
- Record Identifier
- 9984040473502771
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