Further assessment of a pharmacological effect of Tris buffer

1. Data are presented confirming that Tris buffer can potentiate teleost melanophore responses to noradrenalin, as recently reported for the first time in Poecilia reticulata (Visconti and Castrucci, 1985). 2. In vitro melanophore responses of Pseudopleuronectes americanus were compared in Tris- and bicarbonate-buffered physiological saline solutions. 3. Dose-response curves demonstrate that Tris significantly potentiates melanophore responses to noradrenalin doses between 10(-6) and 10(-5)M in this species. 4. Time-response curves further characterized this effect of Tris on melanophore activity, quantifying the enhancement of the melanosome aggregation rate as well as the dose-related equilibrium levels.