Biochemical and functional studies on thromboxane/prostaglandin receptors

Tahraoui, L.; Floch, Anne; Cavero, Icilio

doi:10.1016/0268-9499(90)90283-p

Cited by 1 publication

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“…Ca2+-channel blockers such as verapamil inhibit the binding of PAF to PAF receptors on platelets [31,32] and neutrophils [33], suggesting that these receptors are closely linked to Ca2+ channels in the plasma membrane. The inhibition is complex, showing competitive as well as non-competitive kinetics.…”

Section: Discussionmentioning

confidence: 99%

Regulation of the receptor for platelet-activating factor on human platelets

Burgers¹,

Akkerman²

1993

Biochemical Journal

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Human platelets possess about 300 receptors for platelet-activating factor (PAF) per cell with a Kd of about 0.2 nM. In the present study we investigated whether these receptors are subject to intracellular control mechanisms. Preincubation with the protein kinase C inhibitor staurosporine had no effect, and also agents that increase cyclic AMP failed to change the binding of [3H]PAF. The Ca(2+)-calmodulin inhibitors W-7 and sphingosine decreased PAF binding by 50-80%. Inhibition of energy metabolism induced a fall in adenylate energy charge [AEC = ([ATP] + 1/2[ADP])([ATP + ADP + AMP])] and an almost parallel decrease in specific [3H]PAF binding without changing the Kd. Restoration of the AEC restored the [3H]PAF binding. Abrupt arrest of energy metabolism during binding of [3H]PAF left the binding unchanged until the metabolic ATP level had decreased by about 90%. These data indicate that PAF receptors on human platelets are under close intracellular control, possibly via a Ca(2+)-calmodulin-dependent phosphorylation/dephosphorylation process.

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Section: Discussionmentioning

confidence: 99%