On primary and secondary processes of photoinduced muscle response in Anodonta-larvae

Lábos, Elemér and Turcsányi, Béla (1966) On primary and secondary processes of photoinduced muscle response in Anodonta-larvae. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 33. pp. 45-60. ISSN 0365-3005

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Abstract

Authors investigated photosensitized rhythmic and tonic muscular contractions of fresh-water mussel larvae (glochidia of Anodonta cygnea L.). The used sensitors were different aromatic heterocyclic compounds (xanthenes, phenazines, phenoxazines, phenothiazines). The sensitor ability was characterized by the time needed to the closing of 50 per cent of the animals (t₅₀). The obtained sequence of sensitor-effectivity is RB > MB > (TB THIO) > NR > SG > (NBS, AO, NV) > RH > ERY > ХА > (PYR, EO)> U > GC Considering the structure (effect correlations, two factors are emphasized. Firstly the intramolecular Chargetransfer (n → π* transition), secondly the spin-orbit coupling (in the case of xanthenes). Dose-effect curve of rose bengal suggests adsorption of the sensitors on macromolecules. In this compact system even 10⁻⁷ M/lit rose bengal could well sensitize. The reaction has two stages: the reversible with increasing frequency of phasic contractions, and the irreversible-one. In case of acridine orange inhibitor-effect of KCN, CdCl₂, L-cysteine, chlorpromazine, 5-HT was demonstrated. Considering these inhibitions the terminal oxidation (proton and electron mediation) seem to be important in the process. The electron transfer is supposed to take place with cytochromoxidase. In about 30-50 mM concentration NaCl₂, CaCl, MgCl₂ are potentiating the effect of xanthenes. The reaction in case of acridine orange is not the same (tonus is potentiated, rhythmic response is not). Solvents containing D₂O inhibit the rhythmic activity. Tonus is not depressed by D₂O. The phenomenon is supposed to be connected to slower reversible dehydratation (hydratation of the photoproducts in D₂O.

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