Affiliation:
1. Department of Neurophysiology, Tohoku University Graduate School of Medicine and Core Research for Evolutional Science and Technology, Sendai 980-8575, Japan
Abstract
Using patch- and carbon-fiber electrodes, we studied release phenomena of adenine nucleotides and serotonin from megakaryocytes isolated from the bone marrow of the mouse. Megakaryocytes express ionotropic purinergic receptors on their surfaces. Under the condition of whole cell recording, the cells showed spikelike spontaneous inward currents. The spontaneous currents were carried by cations and had amplitudes of 30–800 pA at –43 mV and durations of 0.1–0.3 s. Pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS; 100 μM) and suramin (100 μM), purinoceptor-blocking agents, depressed the currents reversibly. It is thought that the receptor involved was the P2X1 subtype on the cell and that the currents were due to activation of the P2X1 receptor by adenine nucleotides released from the cell. The currents showed a skewed amplitude distribution, suggesting variation of vesicular contents and/or distinct localization or varied density of receptors on the cell. Frequency of the spontaneous inward currents was enhanced by external application of platelet-activating substances, thrombin (0.4 U/ml), phorbol ester (100 nM), and ADP (2 μM), at low concentrations. With a carbon-fiber electrode, which can detect oxidizable substances including serotonin, spikelike oxidation currents from the external surface of the megakaryocyte were detected. The frequency of the oxidation currents increased remarkably after the application of thrombin (10 U/ml). The majority of the oxidation currents coincided with the rising phase of the whole cell currents, suggesting corelease of serotonin and adenine nucleotide from the same vesicle. We concluded that megakaryocytes store adenine nucleotides and serotonin in the same vesicle and release them simultaneously in a discrete manner.
Publisher
American Physiological Society
Reference45 articles.
1. Altered platelet serotonin 5-HT2A receptor density but not second messenger inositol trisphosphate levels in drug-free schizophrenic patients
2. Bokvist K, Holmqvist M, Gromada J, and Rorsman P. Compound exocytosis in voltage-clamped mouse pancreatic β-cells revealed by carbon fibre amperometry. Pflügers Arch 439: 634–645, 2000.
3. Inherited Platelet δ-Storage Pool Disease in Dogs Causing Severe Bleeding: An Animal Model for a Specific ADP Deficiency
4. Chen D, Bernstein AM, Lemons PP, and Whiteheart SW. Molecular mechanisms of platelet exocytosis: role of SNAP-23 and syntaxin 2 in dense core granule release. Blood 95: 921–929, 2000.
5. Chow RH and von Rueden L. Electrochemical detection of secretion from single cells. In: Single-Channel Recording (2nd ed), edited by Sakmann B and Neher E. New York: Plenum, 1995, p. 245–275.
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