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Thromboxane A2/prostaglandin H2 mobilizes calcium in human blood platelets.
Am J Physiol. 1985 Jul; 249(1 Pt 2):H1-7.AJ

Abstract

The present study investigated the mechanism by which thromboxane A2/prostaglandin H2 (TXA2/PGH2) stimulates platelet activation. Previous studies in isolated platelet vesicles have suggested that TXA2/PGH2 functions to release calcium from intraplatelet stores. On this basis, we investigated whether TXA2/PGH2 causes mobilization of calcium in intact platelets. Calcium redistribution was measured using the fluorescent probe, chlortetracycline (CTC), and a photon-counting microspectrofluorometer. Human platelet-rich plasma was incubated with CTC (50 microM) for 40 min at 25 degrees C. Shape change was induced with arachidonic acid (AA, 100 microM) or ADP (0.75-1.0 microM). It was found that AA addition resulted in a significant release of intraplatelet calcium. This release was blocked by inhibition of the cyclooxygenase with indomethacin (20 microM) or the specific TXA2/PGH2 antagonist, 13-azaprostanoic acid (13-APA, 100 microM). On the other hand, neither indomethacin nor 13-APA had any effect on calcium release stimulated by ADP. However, prostacyclin (13 nM) inhibited both AA- and ADP-induced calcium release. These findings provide evidence that cyclooxygenase products of AA, i.e., TXA2 and/or PGH2 directly caused the mobilization of intraplatelet calcium. Furthermore, this calcium mobilization appears to be mediated through a specific TXA2/PGH2 receptor interaction.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

3925795

Citation

Brace, L D., et al. "Thromboxane A2/prostaglandin H2 Mobilizes Calcium in Human Blood Platelets." The American Journal of Physiology, vol. 249, no. 1 Pt 2, 1985, pp. H1-7.
Brace LD, Venton DL, Le Breton GC. Thromboxane A2/prostaglandin H2 mobilizes calcium in human blood platelets. Am J Physiol. 1985;249(1 Pt 2):H1-7.
Brace, L. D., Venton, D. L., & Le Breton, G. C. (1985). Thromboxane A2/prostaglandin H2 mobilizes calcium in human blood platelets. The American Journal of Physiology, 249(1 Pt 2), H1-7.
Brace LD, Venton DL, Le Breton GC. Thromboxane A2/prostaglandin H2 Mobilizes Calcium in Human Blood Platelets. Am J Physiol. 1985;249(1 Pt 2):H1-7. PubMed PMID: 3925795.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Thromboxane A2/prostaglandin H2 mobilizes calcium in human blood platelets. AU - Brace,L D, AU - Venton,D L, AU - Le Breton,G C, PY - 1985/7/1/pubmed PY - 1985/7/1/medline PY - 1985/7/1/entrez SP - H1 EP - 7 JF - The American journal of physiology JO - Am J Physiol VL - 249 IS - 1 Pt 2 N2 - The present study investigated the mechanism by which thromboxane A2/prostaglandin H2 (TXA2/PGH2) stimulates platelet activation. Previous studies in isolated platelet vesicles have suggested that TXA2/PGH2 functions to release calcium from intraplatelet stores. On this basis, we investigated whether TXA2/PGH2 causes mobilization of calcium in intact platelets. Calcium redistribution was measured using the fluorescent probe, chlortetracycline (CTC), and a photon-counting microspectrofluorometer. Human platelet-rich plasma was incubated with CTC (50 microM) for 40 min at 25 degrees C. Shape change was induced with arachidonic acid (AA, 100 microM) or ADP (0.75-1.0 microM). It was found that AA addition resulted in a significant release of intraplatelet calcium. This release was blocked by inhibition of the cyclooxygenase with indomethacin (20 microM) or the specific TXA2/PGH2 antagonist, 13-azaprostanoic acid (13-APA, 100 microM). On the other hand, neither indomethacin nor 13-APA had any effect on calcium release stimulated by ADP. However, prostacyclin (13 nM) inhibited both AA- and ADP-induced calcium release. These findings provide evidence that cyclooxygenase products of AA, i.e., TXA2 and/or PGH2 directly caused the mobilization of intraplatelet calcium. Furthermore, this calcium mobilization appears to be mediated through a specific TXA2/PGH2 receptor interaction. SN - 0002-9513 UR - https://www.unboundmedicine.com/medline/citation/3925795/Thromboxane_A2/prostaglandin_H2_mobilizes_calcium_in_human_blood_platelets_ L2 - https://journals.physiology.org/doi/10.1152/ajpheart.1985.249.1.H1?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -