著者

石橋 貴昭

出版者

日本動物学会

雑誌

動物学雑誌 (ISSN:00445118)

巻号頁・発行日

vol.69, no.11, pp.336-343, 1960-11

---

The present reports are concerned with the analysis of the action of potassium ion on fish scale melanophores. 1. Using three species of teleosts, Carp (Carassius carassius), Funa (Cyprinus auratus) and Medaka (Oryzias latipes), the experiments were performed to ascertain whether potassium ion acts directly upon the melanophores or stimulates the nervous elements which are left alive in the isolated fish scale. 2. In prolonged application of potassium ion, it was observed that there were differences of reaction according to the locality of the melanophores in a scale. Moreover, the aggregation of the pigment granules within the melanophore which was induced by potassium ion had a transient phenomena. 3.The effectiveness of adrenalin in various concentrations upon the duration of the pigment aggregation to be induced by this agent has been examined. As the concentrations of adrenalin were increased, more and more the duration of pigment aggregation was prolonged. 4. The effect of denervation of the melanophore on the response to potassium ion was studied. The scales were pulled out from their pokets with fine forcepts and immediately slipped back into their pockets, thus severing all connections with the nervous system and allowing time for degeneration. In tests of the effects of denervation on the response to potassium ion during the period of degeneration, the scales which had been withdrawn were compared with normal scales and with scales which had recovered from the denervated state. In three hours after the operation the magnitude of centripetal migration of pigment granules within the melanophore reached only about one-half that of normal scale melanophore. From 18 to 20 hours after the operation, the response of melanophores to potassium ion had disappeared. Corresponding to the passage of time after the operation, however, the response of melanophores was actually re-established and it was the same as that of a normal scale. It may be suggested that these facts have relations with disintegration of the nerve fibers, including terminal structure connected with the melanophore, and a regrowth of them. 5. Both normal and denervated melanophore respond cleary to adrenalin. Furthermore, the melanophores which were originally insensitive to potassium ion, and the redispersed melanophores in prolonged application of this ion, were certainly responsive to adrenalin, thus suggesting a difference between potassium ion and adrenalin in mechanism of action to the melanophore. 6. It was assumed that potassium ion acts indirectly upon the melanophores through the never fibers which are left alive in an isolated acale. The failure or incompleteness of the response to potassium ion of the normal scale melanophores may be also explained by the lack or disintegration of the melanophore nerve.