. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MCH AGGREGATES MELANOSOMES IN FISH 365 I00r. FIGURE 4. Typical recording showing that the alpha adrenolytic agent, phentolamine (PA), did not block the melanin-aggregating effect of MCH in the topmouth gudgeon, Pseudorasbora parva. Ordinate: magnitude of response as percentage of the maximal pigment aggregation attained finally by 5 X 10~5 M norepinephrine (NE). 50 mM K+ Ringer (K+) was used to stimulate adrenergic neural elements around the melanophores, and the action was shown to be antagonized by phentolamine (PA). The m
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MCH AGGREGATES MELANOSOMES IN FISH 365 I00r. FIGURE 4. Typical recording showing that the alpha adrenolytic agent, phentolamine (PA), did not block the melanin-aggregating effect of MCH in the topmouth gudgeon, Pseudorasbora parva. Ordinate: magnitude of response as percentage of the maximal pigment aggregation attained finally by 5 X 10~5 M norepinephrine (NE). 50 mM K+ Ringer (K+) was used to stimulate adrenergic neural elements around the melanophores, and the action was shown to be antagonized by phentolamine (PA). The melanosome-aggregating response to MCH proceeded quite normally even in the absence of Ca ions. This is in marked contrast to the alpha-MSH action on teleostean chromatophores, in which Ca2+ was definitely required (Fujii and Miya- shita, 1980;IgaandTakabatake, 1982; Oshima and Fujii, 1985). Melanophores of the European eel, Anguilla anguilla, already have been recog- nized to be influenced only weakly by the nervous system (Neill, 1940; Gilham and Baker, 1984). Recently, Baker and Ranee (1983), however, indicated that their mela- nophores were responsive to MCH. Although the species used was different, melano- phores of the Japanese eel (A. japonicd) were found in this study to respond quite well to MCH by pigment aggregation. Effect of MCH on cholinergically innervated melanophores MCH effectively induced the aggregation of melanophore pigment in the translu- cent glass catfish, Kryptopterus bicirrhi, and the Japanese common siluroid, Parasi- lurus asotus, as seen in Figures 5 and 6, respectively. Both fish belong to the family Siluridae (Siluriformes), and recently have been shown to have melanophores cholin- ergically controlled (Fujii and Miyashita, 1976; Fujii et ai, 1982; cf. also Table I). The action of MCH was not inhibited by atropine, a muscarinic cholinolytic, but the pigment-aggregating effect of K+ was completely blocked by the same drug (Fig. 5). In addition, diva
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
