Tachibana T, Nawa T. Effects of trifluoperazine and amiloride on the extrusion of axoplasmic Ca++ by rapidly adapting and slowly adapting type I cutaneous mechanoreceptors: an electron-microscopic study using the oxalate-antimonate method.
Somatosens Mot Res 1994;
11:19-25. [PMID:
8017141 DOI:
10.3109/08990229409028854]
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Abstract
Influences of Ca++ transport inhibitors on the extrusion of cytosolic Ca++ from axon terminals of oral mucosal mechanoreceptors were cytochemically studied through the use of trifluoperazine (TFP), a Ca++ pump inhibitor, and amiloride, a Na+/Ca++ exchanger inhibitor. Palates of Mongolian gerbils were isolated after perfusion with normal, TFP-containing, or amiloride-containing HEPES-buffered saline, and then mechanically stimulated in the same buffer. Cytosolic Ca++ in axon terminals at 2 min after the stimulation was visualized by means of an oxalate-antimonate method using microwave fixation, and then evaluated electron-microscopically. TFP was found to inhibit the Ca++ extrusion from axon terminals of Meissner corpuscles, but not from those of Merkel cell-axon complexes. Conversely, amiloride severely reduced the Ca++ extrusion from axon terminals of Merkel cell-axon complexes, but not from those of Meissner corpuscles. These results suggest that cytosolic Ca++ extrusion from axon terminals of rapidly adapting and slowly adapting type I mechanoreceptors is regulated by a Ca++ pump and an Na+/Ca++ exchanger, respectively.
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