Tris buffer effects on melanophore aggregating responses.
The adverse effects of tris (hydroxymethyl)-aminomethane (Tris) are for the first time reported on melanophore responses to agonists and potassium chloride. Melanophore responses in Tris- or bicarbonate-buffered solutions were compared. In the presence of Tris, the cumulative dose-response curve to norepinephrine was significantly shifted to the left, whereas methoxamine dose-response curves were similar in both buffers. The percentage aggregation in response to synthetic MCH (melanin concentrating hormone) was not affected by Tris in the bathing medium. The cumulative dose-response curve to potassium chloride was leftward shifted (one log case) in Tris-buffered solution. These results suggest that in fish melanophore preparations Tris might exert its actions on the presynaptic membrane and/or on the synaptic cleft enzyme COMT, drawing on a greater availability of neurotransmitters at the melanophore membrane receptors.
Visconti
M A
MA
Castrucci
A M
AM
D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology; D002021:Buffers; D002449:Cell Aggregation / Q000187:drug effects; D005399:Fishes; D008547:Melanophores / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008729:Methoxamine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D014325:Tromethamine / Q000494:pharmacology*
D001639:Bicarbonates; D002021:Buffers; D014325:Tromethamine; D008729:Methoxamine; D011188:Potassium; D009638:Norepinephrine