Fig. 6. Secreted fluid rhodamine 123 concentration as a function of bathing saline rhodamine 123 concentration for cricket tubules set up in Ramsay assays. Each point shows the mean ± S.E.M. for N=6–28 tubules. The solid line represents the fit to the Michaelis–Menten equation by non-linear regression analysis. The inset shows the ratio of the concentration of rhodamine 123 in the secreted fluid to that in the bathing medium (S/M) as a function of bathing medium rhodamine 123 concentration.