Assay of Melanotropic Peptides in an <em>in Vitro</em> Mammalian System.

A reproducible and sensitive assay for melanotropic agents is described employing mouse melanoma cells in culture and measuring tyrosinase activity in terms of production of tritiated water from L-(ring-3,5-&#179;H)-tyrosine. Molar concentrations of peptides inducing one-half maximal stimulation of tyrosinase activity were: β-MSH, 1 &#177; 2 &#215; 10-9; α-MSH and βh-LPH, 1 &#177; 2 &#215; 10-8; ACTHp, 1 &#177; 2 &#215; 10-7. βp9-18-MSH and melanotropin potentiating factor, βs88-91-LPH exhibited no activity at concentrations as high as 10-5M. [ABSTRACT FROM AUTHOR]