Guanine nucleotides inhibit agonist-stimulated arachidonic acid release in both intact and saponin-permeabilized human platelets |
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Authors: | A G Rehm H Wu S P Halenda |
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Institution: | Department of Pharmacology, University of Missouri School of Medicine, Columbia 65212. |
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Abstract: | The effects of guanine nucleotides on arachidonic acid (AA) release were studied in intact and saponin-permeabilized human platelets. While GTPS] itself caused a stimulation of AA release in permeabilized cells, GTPS], GDPS], GTP, ATP and other nucleotides inhibited AA release in response to thrombin and other agonists in intact, as well as permeabilized platelets. Inhibition of agonist-stimulated AA release by nucleotides was partially attenuated by addition of ADP, and was abolished by prior stimulation of platelets to discharge the ADP-containing dense granules. These results suggest: (i) that released ADP plays an important contributory role in agonist-stimulated platelet AA release, and (ii) that guanine nucleotides can modulate platelet activation through an extracellular action which is distinct from their effects on G-proteins. |
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