[Extracellular ATP evoked catecholamine release and inositol phosphates formation in cultured porcine adrenal medullary cells].
ATP is ubiquitously present in neural tissues and is released during nerve stimulation. It is known that splanchnic nerve terminals located in adrenal medulla also contain acetylcholine and ATP. These substances may be released concomitantly with nerve stimulation. ATP can exert its effects on neuron-effector junctions by acting directly as a neurotransmitter by increasing or decreasing the release of other neurotransmitters or by modulating their actions. Chern et al. reported that ATP and adenosine inhibited acetylcholine stimulated secretion of catecholamine from isolated bovine adrenal medullary cells. However, Kim et al. showed that extracellular ATP stimulated catecholamine secretion from cultured bovine adrenal medullary cells. Therefore, we investigated the effect of ATP on second messengers levels in cultured porcine adrenal medullary cells as well as catecholamine release from the cells. ATP (500 microM-5mM) evoked catecholamine release significantly (p < 0.05). An unhydrolyzable ATP analogue, ATP gamma S, was several times more potent than ATP in the secretion. ATP-evoked maximal secretion of catecholamine was several times less potent than that evoked by carbachol. Removal of extracellular Ca2+ did not effectively inhibit ATP-induced secretion. 45Ca2+ influx was not observed by the addition of ATP. These results indicated that the catecholamine secretion induced by ATP was independent of extracellular Ca2+. ATP evoked cAMP production slightly at 1mM and did not affect cGMP content. On the other hand, ATP (100 microM-5mM) induced a remarkable increase in inositol trisphosphate, a messenger for mobilization of Ca2+ from intracellular storage sites.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Clinical Pathology, University of Tsukuba.
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Isobe
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Nakai
D000255:Adenosine Triphosphate / Q000494:pharmacology* / Q000502:physiology; D000313:Adrenal Medulla / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002395:Catecholamines / Q000378:metabolism*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis; D006152:Cyclic GMP / Q000096:biosynthesis; D007295:Inositol Phosphates / Q000096:biosynthesis*; D013268:Stimulation, Chemical; D013552:Swine
D002395:Catecholamines; D007295:Inositol Phosphates; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D006152:Cyclic GMP; D002118:Calcium