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Insulin induces the release of vasodilator compounds from platelets by a nitric oxide-G kinase-VAMP-3-dependent pathway.

Randriamboavonjy V, Schrader J, Busse R, Fleming I - J. Exp. Med. (2004)

Bottom Line: Insulin failed to relax endothelium-intact rings of porcine coronary artery.Insulin induced the release of adenosine trisphosphate (ATP), adenosine, and serotonin from platelet-dense granules in a NO-dependent manner.The mechanism of dense granule secretion involves the G kinase-dependent association of syntaxin 2 with vesicle-associated membrane protein 3.

View Article: PubMed Central - PubMed

Affiliation: Institut für Kardiovaskuläre Physiologie, Klinikum der J.W.Goethe-Universität, D-60590 Frankfurt am Main, Germany.

ABSTRACT
Insulin-induced vasodilatation is sensitive to nitric oxide (NO) synthase (NOS) inhibitors. However, insulin is unable to relax isolated arteries or to activate endothelial NOS in endothelial cells. Since insulin can enhance platelet endothelial NOS activity, we determined whether insulin-induced vasodilatation can be attributed to a NO-dependent, platelet-mediated process. Insulin failed to relax endothelium-intact rings of porcine coronary artery. The supernatant from insulin-stimulated human platelets induced complete relaxation, which was prevented by preincubation of platelets with a NOS inhibitor, the soluble guanylyl cyclase inhibitor, NS 2028, or the G kinase inhibitor, KT 5823, and was abolished by an adenosine A2A receptor antagonist. Insulin induced the release of adenosine trisphosphate (ATP), adenosine, and serotonin from platelet-dense granules in a NO-dependent manner. This response was not detected using insulin-stimulated platelets from endothelial NOS-/- mice, although a NO donor elicited ATP release. Insulin-induced ATP release from human platelets correlated with the association of syntaxin 2 with the vesicle-associated membrane protein 3 but was not associated with the activation of alphaIIbbeta3 integrin. Thus, insulin elicits the release of vasoactive concentrations of ATP and adenosine from human platelets via a NO-G kinase-dependent signaling cascade. The mechanism of dense granule secretion involves the G kinase-dependent association of syntaxin 2 with vesicle-associated membrane protein 3.

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Pharmacological characterization of the platelet-derived relaxing factor. (a) Effect of the nonselective adenosine receptor antagonist CPT (10 μmol/L, 30 min) and the selective A2 receptor antagonist CSC (1 μmol/L, 30 min) on the relaxation elicited by a factor derived from insulin (1 μmol/L, 10 min)-stimulated washed human platelets. (b) Effect of inclusion of adenosine deaminase (50 U/ml) on the relaxing effect of the supernatant from insulin-stimulated platelets. (c–f) Effect of adenosine receptor antagonists on the adenosine- and ATP-induced relaxation of the porcine coronary artery. Endothelium-intact rings of porcine coronary artery were preconstricted with U46619 (0.01–0.5 μmol/L), and concentration–relaxation curves to adenosine (c and d) and ATP (e and f) were obtained. Experiments were performed in the absence (CTL) and the presence of CPT (10 μmol/L) or CSC (1 μmol/L). The results shown represent the mean ± SEM of data obtained in six to eight independent experiments. *P < 0.05 and ***P < 0.001 versus the response obtained in the absence of inhibitor.
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fig3: Pharmacological characterization of the platelet-derived relaxing factor. (a) Effect of the nonselective adenosine receptor antagonist CPT (10 μmol/L, 30 min) and the selective A2 receptor antagonist CSC (1 μmol/L, 30 min) on the relaxation elicited by a factor derived from insulin (1 μmol/L, 10 min)-stimulated washed human platelets. (b) Effect of inclusion of adenosine deaminase (50 U/ml) on the relaxing effect of the supernatant from insulin-stimulated platelets. (c–f) Effect of adenosine receptor antagonists on the adenosine- and ATP-induced relaxation of the porcine coronary artery. Endothelium-intact rings of porcine coronary artery were preconstricted with U46619 (0.01–0.5 μmol/L), and concentration–relaxation curves to adenosine (c and d) and ATP (e and f) were obtained. Experiments were performed in the absence (CTL) and the presence of CPT (10 μmol/L) or CSC (1 μmol/L). The results shown represent the mean ± SEM of data obtained in six to eight independent experiments. *P < 0.05 and ***P < 0.001 versus the response obtained in the absence of inhibitor.

Mentions: Both the nonselective adenosine receptor antagonist cylcopentyl-theophylline (CPT, 10 μmol/L) and the selective A2 adenosine receptor antagonist 8-(3-chlorostyryl)caffeine (CSC, 1 μmol/L) significantly inhibited the relaxation elicited by the supernatant from insulin-stimulated platelets (Fig. 3 a). Moreover, inclusion of adenosine deaminase in the supernatant to convert adenosine to inosine significantly inhibited the relaxing effect of the supernatant from insulin-stimulated platelets (Fig. 3 b). Neither the P2 purinoceptor antagonist, pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt (50 μmol/L), nor the P2Y receptor antagonist 3′-phosphoadenosine 5′-phosphosulfate (10 μmol/L) affected the relaxation elicited by insulin-stimulated platelets (not depicted).


Insulin induces the release of vasodilator compounds from platelets by a nitric oxide-G kinase-VAMP-3-dependent pathway.

Randriamboavonjy V, Schrader J, Busse R, Fleming I - J. Exp. Med. (2004)

Pharmacological characterization of the platelet-derived relaxing factor. (a) Effect of the nonselective adenosine receptor antagonist CPT (10 μmol/L, 30 min) and the selective A2 receptor antagonist CSC (1 μmol/L, 30 min) on the relaxation elicited by a factor derived from insulin (1 μmol/L, 10 min)-stimulated washed human platelets. (b) Effect of inclusion of adenosine deaminase (50 U/ml) on the relaxing effect of the supernatant from insulin-stimulated platelets. (c–f) Effect of adenosine receptor antagonists on the adenosine- and ATP-induced relaxation of the porcine coronary artery. Endothelium-intact rings of porcine coronary artery were preconstricted with U46619 (0.01–0.5 μmol/L), and concentration–relaxation curves to adenosine (c and d) and ATP (e and f) were obtained. Experiments were performed in the absence (CTL) and the presence of CPT (10 μmol/L) or CSC (1 μmol/L). The results shown represent the mean ± SEM of data obtained in six to eight independent experiments. *P < 0.05 and ***P < 0.001 versus the response obtained in the absence of inhibitor.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211801&req=5

fig3: Pharmacological characterization of the platelet-derived relaxing factor. (a) Effect of the nonselective adenosine receptor antagonist CPT (10 μmol/L, 30 min) and the selective A2 receptor antagonist CSC (1 μmol/L, 30 min) on the relaxation elicited by a factor derived from insulin (1 μmol/L, 10 min)-stimulated washed human platelets. (b) Effect of inclusion of adenosine deaminase (50 U/ml) on the relaxing effect of the supernatant from insulin-stimulated platelets. (c–f) Effect of adenosine receptor antagonists on the adenosine- and ATP-induced relaxation of the porcine coronary artery. Endothelium-intact rings of porcine coronary artery were preconstricted with U46619 (0.01–0.5 μmol/L), and concentration–relaxation curves to adenosine (c and d) and ATP (e and f) were obtained. Experiments were performed in the absence (CTL) and the presence of CPT (10 μmol/L) or CSC (1 μmol/L). The results shown represent the mean ± SEM of data obtained in six to eight independent experiments. *P < 0.05 and ***P < 0.001 versus the response obtained in the absence of inhibitor.
Mentions: Both the nonselective adenosine receptor antagonist cylcopentyl-theophylline (CPT, 10 μmol/L) and the selective A2 adenosine receptor antagonist 8-(3-chlorostyryl)caffeine (CSC, 1 μmol/L) significantly inhibited the relaxation elicited by the supernatant from insulin-stimulated platelets (Fig. 3 a). Moreover, inclusion of adenosine deaminase in the supernatant to convert adenosine to inosine significantly inhibited the relaxing effect of the supernatant from insulin-stimulated platelets (Fig. 3 b). Neither the P2 purinoceptor antagonist, pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) tetrasodium salt (50 μmol/L), nor the P2Y receptor antagonist 3′-phosphoadenosine 5′-phosphosulfate (10 μmol/L) affected the relaxation elicited by insulin-stimulated platelets (not depicted).

Bottom Line: Insulin failed to relax endothelium-intact rings of porcine coronary artery.Insulin induced the release of adenosine trisphosphate (ATP), adenosine, and serotonin from platelet-dense granules in a NO-dependent manner.The mechanism of dense granule secretion involves the G kinase-dependent association of syntaxin 2 with vesicle-associated membrane protein 3.

View Article: PubMed Central - PubMed

Affiliation: Institut für Kardiovaskuläre Physiologie, Klinikum der J.W.Goethe-Universität, D-60590 Frankfurt am Main, Germany.

ABSTRACT
Insulin-induced vasodilatation is sensitive to nitric oxide (NO) synthase (NOS) inhibitors. However, insulin is unable to relax isolated arteries or to activate endothelial NOS in endothelial cells. Since insulin can enhance platelet endothelial NOS activity, we determined whether insulin-induced vasodilatation can be attributed to a NO-dependent, platelet-mediated process. Insulin failed to relax endothelium-intact rings of porcine coronary artery. The supernatant from insulin-stimulated human platelets induced complete relaxation, which was prevented by preincubation of platelets with a NOS inhibitor, the soluble guanylyl cyclase inhibitor, NS 2028, or the G kinase inhibitor, KT 5823, and was abolished by an adenosine A2A receptor antagonist. Insulin induced the release of adenosine trisphosphate (ATP), adenosine, and serotonin from platelet-dense granules in a NO-dependent manner. This response was not detected using insulin-stimulated platelets from endothelial NOS-/- mice, although a NO donor elicited ATP release. Insulin-induced ATP release from human platelets correlated with the association of syntaxin 2 with the vesicle-associated membrane protein 3 but was not associated with the activation of alphaIIbbeta3 integrin. Thus, insulin elicits the release of vasoactive concentrations of ATP and adenosine from human platelets via a NO-G kinase-dependent signaling cascade. The mechanism of dense granule secretion involves the G kinase-dependent association of syntaxin 2 with vesicle-associated membrane protein 3.

Show MeSH
Related in: MedlinePlus