Abstract
1. The specificity of platelet receptor sites for 5-HT uptake and for the rapid morphological change and aggregation was investigated with 5-hydroxy-tryptamine (5-HT) and seventeen analogues as well as with some antagonists of 5-HT.
2. The analogues, with the exception of 5-hydroxy-N'N'-dibutyltryptamine, caused the rapid morphological change in platelets. In concentrations below those needed to produce the agonistic action (viz. 0.05-2.0 μM), these analogues themselves inhibited competitively the shape change caused by 5-HT.
3. The velocity of change in shape caused by 5-HT was reduced in low Na media.
4. Ten analogues produced platelet aggregation; three of these, viz. 5-methoxy-α-methyltryptamine, 5-hydroxy-α-methyltryptamine and 5-hydroxy-N'N'-diisopropyltryptamine), were approximately equipotent with 5-HT. Six analogues did not induce platelet aggregation.
5. All the analogues which prevented the initial change in shape of platelets caused by 5-HT also inhibited its aggregating effect, apparently competitively with low Ki values (0.02-1.6 μM).
6. As with the inhibition of shape change, the inhibition of aggregation shows relatively low structural specificity of the receptor site.
7. Methysergide was a potent inhibitor of shape change and aggregation (Ki∼0.03 μM); imipramine was much less inhibitory (Ki∼5-10 μM).
8. Only one analogue (5-hydroxy-α-methyltryptamine) was taken up like 5-HT by platelets. All the other analogues inhibited the uptake of 5-HT by platelets (Ki=0.2-2.7 μM).
9. Methysergide was a weak inhibitor of 5-HT uptake (Ki∼125 μM) whereas imipramine was very effective (Ki∼0.3 μM).
10. Our results show that the initial change in shape of platelets is required for and precedes aggregation. The structural specificity of the platelet receptor concerned with shape change and aggregation caused by 5-HT appears low whereas the uptake mechanism is a highly specific one. The uptake probably proceeds through more than one step, the relationship between the steps is not yet clear.
Full text
PDFSelected References
These references are in PubMed. This may not be the complete list of references from this article.
- BORN G. V. Aggregation of blood platelets by adenosine diphosphate and its reversal. Nature. 1962 Jun 9;194:927–929. doi: 10.1038/194927b0. [DOI] [PubMed] [Google Scholar]
- BORN G. V., BRICKNELL J. The uptake of 5-hydroxytryptamine by blood platelets in the cold. J Physiol. 1959 Jun 23;147(1):153–161. doi: 10.1113/jphysiol.1959.sp006230. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BORN G. V. Changes in the distribution of phosphorus in platelet-rich plasma during clotting. Biochem J. 1958 Apr;68(4):695–704. doi: 10.1042/bj0680695. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BORN G. V., GILLSON R. E. Studies on the uptake of 5-hydroxytryptamine by blood platelets. J Physiol. 1959 Jun 11;146(3):472–491. doi: 10.1113/jphysiol.1959.sp006206. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BORN G. V., INGRAM G. I., STACEY R. S. The relationship between 5-hydroxytryptamine and adenosine triphosphate in blood platelets. Br J Pharmacol Chemother. 1958 Mar;13(1):62–64. doi: 10.1111/j.1476-5381.1958.tb00191.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BORN G. V. The fate of 5-hydroxytryptamine in a smooth muscle and in connective tissue. J Physiol. 1962 Apr;161:160–174. doi: 10.1113/jphysiol.1962.sp006879. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BOWMAN R. L., CAULFIELD P. A., UNDENFRIEND S. Spectrophotofluorometric assay in the visible and ultraviolet. Science. 1955 Jul 1;122(3157):32–33. doi: 10.1126/science.122.3157.32. [DOI] [PubMed] [Google Scholar]
- Baumgartner H. R. 5-Hydroxytryptamine uptake and release in relation to aggregation of rabbit platelets. J Physiol. 1969 Apr;201(2):409–423. doi: 10.1113/jphysiol.1969.sp008763. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Baumgartner H. R., Born G. V. Effects of 5-hydroxytryptamine on platelet aggregation. Nature. 1968 Apr 13;218(5137):137–141. doi: 10.1038/218137a0. [DOI] [PubMed] [Google Scholar]
- Baumgartner H. R., Born G. V. The relation between the 5-hydroxytryptamine content and aggregation of rabbit platelets. J Physiol. 1969 Apr;201(2):397–408. doi: 10.1113/jphysiol.1969.sp008762. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Born G. V. Observations on the change in shape of blood platelets brought about by adenosine diphosphate. J Physiol. 1970 Aug;209(2):487–511. doi: 10.1113/jphysiol.1970.sp009176. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Born G. V., Smith J. B. Uptake, metabolism and release of (3H)-adrenaline by human platelets. Br J Pharmacol. 1970 Aug;39(4):765–778. doi: 10.1111/j.1476-5381.1970.tb09903.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- CROSTI P. F., LUCCHELLI P. E. An easy method to determine the serotonin content of human platelets. J Clin Pathol. 1962 Mar;15:191–193. doi: 10.1136/jcp.15.2.191. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Da Prada M., Pletscher A. Isolated 5-hydroxytryptamine organelles of rabbit blood platelets: physiological properties and drug-induced changes. Br J Pharmacol. 1968 Nov;34(3):591–597. doi: 10.1111/j.1476-5381.1968.tb08487.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- GADDUM J. H., PICARELLI Z. P. Two kinds of tryptamine receptor. Br J Pharmacol Chemother. 1957 Sep;12(3):323–328. doi: 10.1111/j.1476-5381.1957.tb00142.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HARDISTY R. M., STACEY R. S. 5-Hydroxytryptamine in normal human platelets. J Physiol. 1955 Dec 29;130(3):711–720. doi: 10.1113/jphysiol.1955.sp005437. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HUGHES F. B., BRODIE B. B. The mechanism of serotonin and catecholamine uptake by platelets. J Pharmacol Exp Ther. 1959 Oct;127:96–102. [PubMed] [Google Scholar]
- MACMILLAN D. C., OLIVER M. F. THE INITIAL CHANGES IN PLATELET MORPHOLOGY FOLLOWING THE ADDITION OF ADENOSINE DIPHOSPHATE. J Atheroscler Res. 1965 Jul-Aug;5(4):440–444. doi: 10.1016/s0368-1319(65)80081-3. [DOI] [PubMed] [Google Scholar]
- MITCHELL J. R., SHARP A. A. PLATELET CLUMPING IN VITRO. Br J Haematol. 1964 Jan;10:78–93. doi: 10.1111/j.1365-2141.1964.tb00681.x. [DOI] [PubMed] [Google Scholar]
- Michal F., Born G. V. Effect of the rapid shape change of platelets on the transmission and scattering of light through plasma. Nat New Biol. 1971 Jun 16;231(24):220–222. doi: 10.1038/newbio231220a0. [DOI] [PubMed] [Google Scholar]
- Michal F. D-receptor for serotonin on blood platelets. Nature. 1969 Mar 29;221(5187):1253–1254. doi: 10.1038/2211253a0. [DOI] [PubMed] [Google Scholar]
- Michal F., Penglis F. Inhibition of serotonin-induced platelet aggregation in relation to thrombus production. J Pharmacol Exp Ther. 1969 Apr;166(2):276–284. [PubMed] [Google Scholar]
- Mustard J. F., Packham M. A. Factors influencing platelet function: adhesion, release, and aggregation. Pharmacol Rev. 1970 Jun;22(2):97–187. [PubMed] [Google Scholar]
- Pletscher A. Metabolism, transfer and storage of 5-hydroxytryptamine in blood platelets. Br J Pharmacol Chemother. 1968 Jan;32(1):1–16. doi: 10.1111/j.1476-5381.1968.tb00423.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pletscher A., da Prada M., Tranzer J. P. Transfer and storage of biogenic monoamines in subcellular organelles of blood platelets. Prog Brain Res. 1969;31:47–52. doi: 10.1016/s0079-6123(08)63226-4. [DOI] [PubMed] [Google Scholar]
- RAND M., REID G. Source of 'serotonin' in serum. Nature. 1951 Sep 1;168(4270):385–385. doi: 10.1038/168385b0. [DOI] [PubMed] [Google Scholar]
- Sinakos Z., Caen J. P. Platelet aggregation in mammalians (human, rat, rabbit, guinea-pig, horse, dog). A comparative study. Thromb Diath Haemorrh. 1967 Feb 28;17(1-2):99–111. [PubMed] [Google Scholar]
- Sneddon J. M. Sodium-dependent accumulation of 5-hydroxytryptamine by rat blood platelets. Br J Pharmacol. 1969 Nov;37(3):680–688. doi: 10.1111/j.1476-5381.1969.tb08506.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- UDENFRIEND S., WEISSBACH H., CLARK C. T. The estimation of 5-hydroxytryptamine (serotonin) in biological tissues. J Biol Chem. 1955 Jul;215(1):337–344. [PubMed] [Google Scholar]
- VANE J. R. A sensitive method for the assay of 5-hydroxytryptamine. Br J Pharmacol Chemother. 1957 Sep;12(3):344–349. doi: 10.1111/j.1476-5381.1957.tb00146.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- VANE J. R. The relative activities of some tryptamine analogues on the isolated rat stomach strip preparation. Br J Pharmacol Chemother. 1959 Mar;14(1):87–98. doi: 10.1111/j.1476-5381.1959.tb00933.x. [DOI] [PMC free article] [PubMed] [Google Scholar]