Ca2+, Mg2+-ionophores X537A and A23,187 (10(-7)-10(-6) M) induced the release of adenine nucleotides adenosine diphosphate (ADP, adenosine triphosphate (ATP), serotonin, beta-glucuronidase, Ca2+, and Mg2+ from washed human platelets. Enzymes present in the cytoplasm or mitochondria, and Zn2+ were not released. The rate of ATP and Ca2+ release measured by firefly lantern extract and murexide dye, respectively, was equivalent to that produced by the physiological stimulant thrombin. Ionophore-induced release of ADP, and serotonin was substantially (approximately 60%) but not completely inhibited by EGTA, EDTA, and high extracellular Mg2+, without significant reduction of Ca2+ release. The ionophore-induced release reaction is therefore partly dependent upon uptake of extracellular Ca2+ (demonstrated using 45Ca), but also occurs to a significant extent due to release into the cytoplasm of intracellular Ca2+. The ionophore-induced release reaction and aggregation of platelets could be blocked by prostaglandin E1 (PGE1) or dibutyryl cyclic AMP. The effects of PGE1, and N6, O2-dibutyryl adenosine 3':5'-cyclic monophosphoric acid (dibutyryl cAMP) were synergistically potentiated by the phosphodiesterase inhibitor theophylline. It is proposed that Ca2+ is the physiological trigger for platelet secretion and aggregation and that its intracellular effects are strongly modulated by adenosine 3':5'-cyclic monophosphoric acid (cyclic AMP).
Skip Nav Destination
Article navigation
1 November 1975
Article|
November 01 1975
Human platelet secretion and aggregation induced by calcium ionophores. Inhibition by PGE1 and dibutyryl cyclic AMP.
M B Feinstein
C Fraser
Online ISSN: 1540-7748
Print ISSN: 0022-1295
J Gen Physiol (1975) 66 (5): 561–581.
Citation
M B Feinstein, C Fraser; Human platelet secretion and aggregation induced by calcium ionophores. Inhibition by PGE1 and dibutyryl cyclic AMP.. J Gen Physiol 1 November 1975; 66 (5): 561–581. doi: https://doi.org/10.1085/jgp.66.5.561
Download citation file:
Sign in
Don't already have an account? Register
Client Account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.
Sign in via your Institution
Sign in via your InstitutionSuggested Content
Threshold and Receptor Reserve in the Action of Neurohypophyseal Peptides : A study of synergists and antagonists of the hydroosmotic response of the toad urinary bladder
J Gen Physiol (August,1970)
The Effect of Calcium Ionophores on Fragmented Sarcoplasmic Reticulum
J Gen Physiol (December,1972)
Lyotropic anions. Na channel gating and Ca electrode response.
J Gen Physiol (February,1983)
Email alerts
Advertisement