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Kobayashi B, Cook IA, Hunter AM, Minzenberg MJ, Krantz DE, Leuchter AF. Can neurophysiologic measures serve as biomarkers for the efficacy of repetitive transcranial magnetic stimulation treatment of major depressive disorder? Int Rev Psychiatry 2017; 29:98-114. [PMID: 28362541 DOI: 10.1080/09540261.2017.1297697] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for Major Depressive Disorder (MDD). There are clinical data that support the efficacy of many different approaches to rTMS treatment, and it remains unclear what combination of stimulation parameters is optimal to relieve depressive symptoms. Because of the costs and complexity of studies that would be necessary to explore and compare the large number of combinations of rTMS treatment parameters, it would be useful to establish reliable surrogate biomarkers of treatment efficacy that could be used to compare different approaches to treatment. This study reviews the evidence that neurophysiologic measures of cortical excitability could be used as biomarkers for screening different rTMS treatment paradigms. It examines evidence that: (1) changes in excitability are related to the mechanism of action of rTMS; (2) rTMS has consistent effects on measures of excitability that could constitute reliable biomarkers; and (3) changes in excitability are related to the outcomes of rTMS treatment of MDD. An increasing body of evidence indicates that these neurophysiologic measures have the potential to serve as reliable biomarkers for screening different approaches to rTMS treatment of MDD.
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Chang SK, Farrell DL, Dougan K, Kobayashi B. Acute idiopathic thrombocytopenic purpura following combined vaccination against measles, mumps, and rubella. THE JOURNAL OF THE AMERICAN BOARD OF FAMILY PRACTICE 1996; 9:53-5. [PMID: 8770810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Watanabe Y, Taniguchi M, Fukamachi N, Sakuma M, Kobayashi B. Effects of gangliosides on cell maturation of murine megakaryocytes in a liquid culture system. Cell Struct Funct 1990; 15:79-84. [PMID: 2357735 DOI: 10.1247/csf.15.79] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Formation of platelet-producing megakaryocytes, the cytoplasm of which showed the terminal stage of cell maturation, heavy granulation and platelet-fields delineated with demarcation membranes, was observed in a short-term culture system, using megakaryocyte-enriched bone marrow cell suspension. Approximately 6-8% of the megakaryocytes changed to the platelet-producing megakaryocytes during 12-hour incubation. In the presence of inhibitors of energy metabolism, formation of the platelet-producing megakaryocytes was inhibited, suggesting that the process is dependent on energy producing systems. Ganglioside GD1a increased both the number of total megakaryocytes and the ratio of the platelet-producing megakaryocytes to total megakaryocytes, while GM1 did not influence the number of total megakaryocytes, but increased the ratio. Gangliosides GM2, GM3 and GD1b showed little effect on either the number of total megakaryocytes or the ratio. The results suggest that ganglioside GD1a stimulates at least two steps of megakaryocyte maturation, the change of megakaryocytic progenitors to megakaryocytes and the subsequent maturation of megakaryocytes to the platelet-producing megakaryocytes, while GM1 stimulates only the latter step of the maturation.
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Ishihara N, Sakamoto H, Iwama M, Kobayashi B. Net increase of platelet membrane tyrosine specific-protein kinase activity by phorbol myristate acetate. Life Sci 1990; 46:29-36. [PMID: 2299969 DOI: 10.1016/0024-3205(90)90053-t] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Tyrosine protein kinase (TPK) activity in rabbit platelets after stimulation by phorbol myristate acetate (PMA) or thrombin was directly estimated by 32P incorporation from (gamma-32P)ATP (adenosine triphosphate) into synthetic peptide angiotensin II. By PMA-treatment a net increase of TPK activity was obtained, while thrombin acted on the TPK quickly but stimulation was limited within the range attained by the control after lengthy incubation. The responsive TPK to these stimulators was localized mainly in membrane but much less in cytosol. The specific activity of the particulate TPK was low in the sonicate of control ice cold platelets but increased about 6-fold when the platelets were incubated at 37 degrees C. On a brief contact of platelets with PMA at 37 degrees C the TPK was fully activated and reached a maximum value about 130% of the control. Determination of phosphotyrosine phosphatase in the stimulated platelet sonicate revealed that its participation in the above described increase of 32P-incorporation was meagre. The quick response suggested a possible role of TPK in the signal transduction through the platelet cell membrane.
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Ishihara N, Iwama M, Kobayashi B. Stabilization of blood platelet microtubular system by staurosporine. Life Sci 1989; 44:1309-16. [PMID: 2716473 DOI: 10.1016/0024-3205(89)90369-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The stimulative effects of phorbol myristate acetate (PMA) on rabbit platelet shape change and platelet adhesion were completely inhibited by staurosporine (STS)-pretreatment. When the platelets were observed by whole mount immuno transmission electron microscopy (TEM), STS was found to stabilize platelet microtubular cytoskeleton. Electrophoretic analysis of the isolated marginal bundles of cytoskeleton after STS-PMA treatment revealed a newly formed 200 K high molecular weight protein band accompanied with heavy losses of tubulin monomers. These bundles of STS-treated platelets as observed in immuno TEM responded poorly to the anti alpha- or beta-tubulin antibody as compared with those of the control platelets. The results suggest that sts favour the specific assembly of tubulin bundles with a possible involvement of the microtubular associated proteins (MAPs). The resultant tight marginal bundles (MB) of cytoskeleton will stabilize the platelets and resist the effects of exogeneously added stimulants such as PMA.
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Fukamachi N, Watanabe Y, Kobayashi B. Inhibition of thrombin-induced platelet aggregation by myristic acid. Thromb Res 1988; 52:227-35. [PMID: 3194898 DOI: 10.1016/0049-3848(88)90082-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Myristate inhibited thrombin-induced aggregation and production of diacylglycerols of rabbit platelets suspended in a modified Tyrode solution. The incorporation of inositol into platelet phospholipids in both steady and activated states was also inhibited by myristate. When platelets were incubated with 32P-inorganic phosphate in the presence of myristate, incorporation of the radioactivity into platelet phosphatidylinositols (PI) was distinctly inhibited, although that into phosphatidic acid (PA) was inhibited relatively little. These results suggest that thrombin-induced breakdown of inositol phospholipids and the metabolic pathway of PA to PI are inhibited by myristate. The saturated fatty acids which have lower and higher molecular weight than myristate revealed a little or no inhibitory effects on the aggregation and on these metabolic changes of platelet lipids, suggesting the specificity of chain-length in the inhibitory action. It is conceivable that the inhibition of thrombin-induced aggregation by myristate is associated with the inhibition of PI-turnover in the platelets treated with the fatty acid.
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Watanabe Y, Taniguchi M, Fukamachi N, Kobayashi B. Effect of gangliosides on murine megakaryocytopoiesis in a liquid culture system. Cell Struct Funct 1988; 13:293-300. [PMID: 3180256 DOI: 10.1247/csf.13.293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Bovine brain gangliosides were applied to primary cultures of murine bone marrow cells to examine the role of gangliosides in development of megakaryocytes. Megakaryocytes in the cultures were detected by staining for a cytoplasmic enzyme, acetylcholinesterase, and divided into two types, 1) immature megakaryocytes which were stained less intensely, and 2) mature ones which were stained intensely. A medium containing total ganglioside fraction from bovine brain increased the number of both immature and mature megakaryocytes in the presence of pokeweed mitogen-stimulated murine spleen cell conditioned medium. Between the two cell types, the number of the mature cells was more significantly increased than the immature cells. The ganglioside GD1a could substitute for the total ganglioside mixture. The results suggested that bovine brain gangliosides potentiated both megakaryocytic proliferation and maturation in vitro.
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Omura S, Nakagawa A, Fukamachi N, Miura S, Takahashi Y, Komiyama K, Kobayashi B. OM-4842, a new platelet aggregation inhibitor from Streptomyces. J Antibiot (Tokyo) 1988; 41:812-3. [PMID: 3403378 DOI: 10.7164/antibiotics.41.812] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Watanabe Y, Kobayashi B. Differential release of calcium, magnesium and serotonin by rabbit and human platelets. JOURNAL OF PHARMACOBIO-DYNAMICS 1988; 11:268-76. [PMID: 3411442 DOI: 10.1248/bpb1978.11.268] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Calcium and magnesium are extracellularly released by platelets during the release reaction. The characteristics of the release of these components by rabbit and human platelets were compared with the release of serotonin. When rabbit platelets were activated by thrombin which induces maximum response, approximately 80% of the platelet serotonin and calcium, but only 50% of platelet magnesium were released. It was suggested that only about one-half of the amount of platelet magnesium was localized in the releasable compartments in the cells. In response to a lower concentration of thrombin, calcium and magnesium were released to a greater extent than was serotonin. When phorbol myristate acetate was added to the rabbit and human platelet suspension serotonin was slowly but calcium and magnesium were rapidly released into extracellular fluid. Platelet factor-4 was also more rapidly released than serotonin by human platelets. The release of calcium and magnesium was analogous to the release of platelet factor-4. It is conceivable that possible pools containing calcium and magnesium but little or no serotonin exist in the platelets and that their contents are more susceptible to mild stimuli than granular serotonin.
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Nakagawa A, Fukamachi N, Yamaki K, Hayashi M, Oh-ishi S, Kobayashi B, Omura S. Inhibition of platelet aggregation by medermycin and it's related isochromanequinone antibiotics. J Antibiot (Tokyo) 1987; 40:1075-6. [PMID: 3624070 DOI: 10.7164/antibiotics.40.1075] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Watanabe Y, Kawada M, Kobayashi B. Effect of insulin on murine megakaryocytopoiesis in a liquid culture system. Cell Struct Funct 1987; 12:311-6. [PMID: 3304669 DOI: 10.1247/csf.12.311] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
To examine the influence of insulin on megakaryocytopoiesis, we tested its effect on murine bone marrow cultures in a liquid culture system. In the presence of pokeweed mitogen-stimulated spleen cell conditioned medium in culture, insulin markedly enhanced megakaryocyte colony formation and increased the number and size of free megakaryocytes seen after 7 days. Many of the cells in cultures with insulin, however, were classified as immature, since they had a basophilic cytoplasm, a low cytoplasmic/nuclear ratio and low acetylcholinesterase activity. It is suggested that insulin potentiates murine marrow megakaryocytopoiesis in vitro, but that this is not accompanied by differentiation of the cells from the immature to mature state.
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Omura S, Nakagawa A, Fukamachi N, Otoguro K, Kobayashi B. Aggreceride, a new platelet aggregation inhibitor from Streptomyces. J Antibiot (Tokyo) 1986; 39:1180-1. [PMID: 3759668 DOI: 10.7164/antibiotics.39.1180] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Ishihara N, Nagao K, Kobayashi B. Tyrosine phosphorylation of platelet protein induced by phorbol ester. Thromb Haemost 1985; 54:579-85. [PMID: 2418523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The presence of phosphotyrosine in proteins from washed rabbit platelets was demonstrated by electrophoresis and by alkali stability of phosphorylated polypeptides. The phosphotyrosine content increased about twofold by treating the platelets with PMA in spite of the fact that the specific activity of labeled ATP was unchanged. It was shown that phosphorylated proteins with apparent molecular weight of 48k, 53k and 250k were alkali-stable. Although phosphorylation of 48k protein in platelets was stimulated by 1 U thrombin as well as by 100 ng PMA, only the phosphorylated samples from PMA-treated platelets were alkali-stable. The 48k protein from platelets stimulated by PMA showed the fivefold increase of 32P-tyrosine content as compared with the control. Relatively lower increase of 32P-serine or 32P-threonine, 2- and 1.7-fold respectively, was thereby observed. The differences in time-sequence between 48k and 250k protein of total and alkali-stable phosphorylations suggested that tyrosine phosphorylation of 48k protein is the earliest event after the PMA-stimulation.
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Watanabe Y, Soda M, Fukamachi N, Kobayashi B. Enhancement of the release reaction not accompanied with enhanced phosphatidylinositol turnover in the reserpinized rabbit blood platelets. Thromb Haemost 1983; 50:595-600. [PMID: 6415850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Thrombin-induced platelet release reaction examined with secretion of calcium and N-acetylglucosaminidase was significantly enhanced in the platelets from reserpine-treated rabbits as compared with the control. On the other hand, 32P-incorporation into phosphatidic acid was suppressed in the reserpinized platelets in activated state. Thrombin induced phosphatidylinositol (PI)-breakdown, which was examined by decreases in radioactivity and content of PI, and an increase in diacylglycerol, was not enhanced in the reserpinized platelets as compared with the control. The phosphorylation of the specific protein coupled to thrombin-induced platelet PI-breakdown was not stimulated in the reserpinized platelets as compared with the control. In contrast to PI, PC-degradation by thrombin was significantly stimulated in the reserpinized platelets. Possible existence of pathway(s) other than that associated with an enhancement of PI-turnover is conceivable as a mechanism involved in platelet release reaction.
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Watanabe Y, Soda M, Fukamachi N, Kobayashi B. Enhancement of the Release Reaction Not Accompanied with Enhanced Phosphatidylinositol Turnover in the Reserpinized Rabbit Blood Platelets. Thromb Haemost 1983. [DOI: 10.1055/s-0038-1665264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
SummaryThrombin-induced platelet release reaction examined with secretion of calcium and N-acetylglucosaminidase was significantly enhanced in the platelets from reserpine-treated rabbits as compared with the control. On the other hand, 32P-incorporation into phosphatidic acid was suppressed in the reserpinized platelets in activated state. Thrombin induced phosphatidylinositol (PI)- breakdown, which was examined by decreases in radioactivity and content of PI, and an increase in diacylglycerol, was not enhanced in the reserpinized platelets as compared with the control. The phosphorylation of the specific protein coupled to thrombin- induced platelet PI-breakdown was not stimulated in the reserpinized platelets as compared with the control. In contrast to PI, PC-degradation by thrombin was significantly stimulated in the reserpinized platelets. Possible existence of pathway(s) other than that associated with an enhancement of Pl-tumover is conceivable as a mechanism involved in platelet release reaction.
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Watanabe Y, Soda M, Kobayashi B. Enhancement of thrombin-induced degradation of phosphatidylcholine in reserpinized rabbit platelets. Thromb Haemost 1981; 46:655-7. [PMID: 7314059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
When 1-(14)C-arachidonic acid-labeled, washed platelets from the reserpinized rabbits were exposed to thrombin, the decrease in radioactivity of phospholipids was significantly stimulated as compared with the control platelets. The increase in radioactivity of fatty acids and their oxygenated metabolites was also stimulated. TLC analysis revealed that the stimulation of the decrease in radioactivity of phospholipids was almost exclusively attributed to that of phosphatidylcholine (PC), and that thrombin induced a slight but significant increase in radioactivity of phosphatidylethanolamine (PE) in the reserpinized platelets. The results suggest that thrombin-induced degradation of PC is enhanced in the reserpinized platelets, and the overproduced fatty acids would be metabolized to the larger amount of oxygenated products which result in the activation of the platelets. Thrombin-induced mobilization of PC to PE in the reserpinized platelet phospholipids was also suggested.
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Kobayashi B, Watanabe Y, Takasugi N, Kurita M. Differential contribution of oxidative and glycolytic energy to thrombin-induced platelet functions. Thromb Haemost 1979; 42:655-65. [PMID: 505372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Watanabe Y, Soda M, Kobayashi B. Enhanced malondialdehyde formation in reserpinized rabbit blood platelets. Thromb Res 1979; 16:25-35. [PMID: 505420 DOI: 10.1016/0049-3848(79)90266-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Shibata S, Kobayashi B. Blood platelets as a possible source of creatine kinase in rat plasma and serum. Thromb Haemost 1978; 39:701-6. [PMID: 705698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The creatine kinase (CK) activity in rat plasma was found to be correlated with that in serum or platelets. Rat serum contained higher activity not only of CK but also of lactate dehydrogenase than the corresponding plasma. The plasma CK activity decreased with increasing age of rats. Only the brain-type isoenzyme of CK was found in plasma, serum and platelets. Contamination of brain-type with muscle-type isoenzyme was detected in rather exceptional cases in which the activity was high among old rats. These results suggest the possible contribution of blood platelets to the CK activity of circulating plasma as well as to the activity in serum in rats.
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Hashimoto S, Shibata S, Kobayashi B. The effect of mitomycin C on platelet aggregation and adenosine 3',5'-monophosphate metabolism. Thromb Haemost 1978; 39:177-85. [PMID: 205972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The effect of Mitomycin C on aggregation, adenosine 3',5'-monophosphate (cyclic AMP) metabolism and reactions induced by thrombin was studied in rabbit platelets. Mitomycin C inhibited the platelet aggregation induced by adenosine diphosphate or thrombin. The level of radioactive cyclic AMP derived from 8-14C adenine or 8-14C adenosine increased after incubating intact platelets with Mitomycin C. Formation of radioactive adenosine triphosphate also increased though mitochondrial oxidation was not stimulated. Similar effect was observed also in rabbit liver. Mitomycin C failed to stimulate platelet adenyl cyclase but inhibited cyclic AMP phosphodiesterase in the absence of theophylline. In the platelets preincubated with Mitomycin C, thrombin-induced inhibition of adenyl cyclase, stimulation of membrane-bound cyclic AMP phosphodiesterase, and release of 250,000 dalton protein from platelet membranes were prevented. These results suggest that Mitomycin C will affect cellular membrane structure and function, and this extranuclear effect of Mitomycin C will lead to inhibition of aggregation in blood platelets.
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Hashimoto S, Shibata S, Kobayashi B. Exterior and interior events in early stage of thrombin-induced platelet aggregation. Thromb Haemost 1977; 38:630-9. [PMID: 202039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Hashimoto S, Shibata S, Kobayashi B. Dependence of platelet adenyl cyclase system on oxidative phosphorylation. THROMBOSIS ET DIATHESIS HAEMORRHAGICA 1975; 34:42-9. [PMID: 171798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The radioactive adenosine 3',5'-monophosphate (cyclic AMP) level derived from 8-14C adenine in intact rabbit platelets decreased in the presence of mitochondrial inhibitor (potassium cyanide) or uncoupler (sodium azide), and markedly increased by the addition of NaF, monoiodoacetic acid (MIA), or 2-deoxy-D-glucose. The stimulative effect of the glycolytic inhibitors was distinctly enhanced by the simultaneous addition of sodium succinate. MIA did neither directly stimulate the adenyl cyclase activity nor inhibit the phosphodiesterase activity. These results suggest that cyclic AMP synthesis in platelets is closely linked to mitochondrial oxidative phosphorylation.
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Shibata S, Kobayashi B. ATP synthesis from ADP by the filtrate of washed rat platelet suspension through cellulose ester membrane: liberation of platelet creatine kinase. Thromb Res 1975; 7:417-24. [PMID: 1188843 DOI: 10.1016/0049-3848(75)90036-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Fujita T, Kobayashi B. Nucleotide incorporation into acid-insoluble fraction of triton X-100 treated rabbit blood platelets. Thromb Res 1975; 7:409-16. [PMID: 1188842 DOI: 10.1016/0049-3848(75)90035-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Shibata S, Kobayashi B. Light scattering changes of edetic acid-treated, washed rat platelets: effect of adenosine diphosphate and calcium ion in relation to chilling. THROMBOSIS ET DIATHESIS HAEMORRHAGICA 1975; 33:508-18. [PMID: 239458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The effe-ts of adenosine diphosphate (ADP) and Ca2+ on platelet morphology were studied in edetic acid (EDTA)-treated, washed platelets of rat by means of light scattering measurement at right angles. ADP caused a transient change of light scattering, which was independent of concentration above 5 muM and of pH between 4 and 10. When the platelets were pretreated with ADP or chilled persistently, Ca2+ also caused another transient change of light scattering. The effect of Ca2+ was abolsihed at pH below 6.5. The velocity of both ADP- and Ca2+-induced response was dependnet on temperature, and the magnitude was reduced by metabolic inhibitors and SH-blocking agents. Adenosine triphosphate (ATP) competitively inhibited the ADP-induced response, but not the Ca2+-induced one. The response to Ca2+ of the control and chilled platelets was compared by scanning electron microgram. Apparent similarity of the effect of chilling on membrane structure to that of ADP was suggested.
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