The action of guanidins on the melanophores of the skin of the frog ( Rana temporaria )

Abstract

The part played by the methylguanidins in metabolism has been recently considered by Noël Paton (1), who pointed out, inter alia , their effect on the tone of skeletal muscle, and adduced evidence to show that the increased tonicity in tetania parathyreopriva is associated with an increase of these substances in the blood (1A). Within the past year this has been confirmed by Kühnau (2). The work by Frank, Stern and Nëthmann (3) indicates that these methyl-guanidins have an activating effect on the sympathetic nerve-endings, a conclusion supported by the effect on the pupil described by Putseys and Swaen (4). A full consideration of the physiological action of the guanidins is given by Fühner in Heffter’s ‘Handbuch der exper. Pharmak.’ (vol. 1, p. 684), Berlin, 1923, with a bibliography; detailed references to the older work are therefore unnecessary.