Dear Editor,

Re; Ms. No. Ka-***

Please find enclosed a revised manuscript with a set of copies.

Thank you for your comments about our manuscript *** submitted last month. The major point was about the specificity of Ca/cAMP effect. Thus we examined the effect of Rp-cAMPS, an antagonist of cAMP, on the morphological features of megakaryocytes. The results was the same in case of H-8. Please refer to a copy of the photograph attached. We added the result in the manuscript (p4, 2nd paragraph). The photograph was not added in the manuscript as it was basically the same as that of H-8. In addition, A23187 induced 5-HT release seemed to be a result of cell lysis as megakaryocyte disappeared after 30 min treatment of A23187. Thus the value of A23187 induced 5-HT release in Fig. 1 meant maximum release (100%). As our explanation was not enough, we added some explanations (p5, 1st paragraph).

And we cannot assay the H-8 induced 5-HT release in the present method because H-8 itself is fluorescent. The quantitation of cAMP in native megakaryocyte is also difficult as the sample is bone marrow cell mixture and cAMP-elevating reagents is required to purify the megakaryocyte. We recognize these are weak points of our study, but we believe the finding reported in this manuscript may be worth publishing.

We are looking forward to your favorable consideration.

Yours sincerely,