. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. STUDIES ON MEMBRANE TRANSPORT. I 635 10J. 2- FIGURE 4. Inhibition of cycloleucine uptake by preincubation of tissue with galactose. Tissue samples were preincubated for 10 minutes in elasmobranch saline with 5 mM galactose or without galactose. The uptake of cycloleucine-"C during a 2-minute incubation without galactose in the medium was then determined. Open circles denote 2-minute uptake of samples preincubated with galactose; closed circles are 2-minute cycloleucine uptake of samples pre- incubated in saline without
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. STUDIES ON MEMBRANE TRANSPORT. I 635 10J. 2- FIGURE 4. Inhibition of cycloleucine uptake by preincubation of tissue with galactose. Tissue samples were preincubated for 10 minutes in elasmobranch saline with 5 mM galactose or without galactose. The uptake of cycloleucine-"C during a 2-minute incubation without galactose in the medium was then determined. Open circles denote 2-minute uptake of samples preincubated with galactose; closed circles are 2-minute cycloleucine uptake of samples pre- incubated in saline without galactose. S = mM cycloleucine ; V = minutes. Each point is mean of four replicates. When tissues were incubated for various time intervals in 5mM galactose, fol- lowed by a 2-minute incubation in cycloleucine, the inhibition of amino acid uptake was a function of the time of previous exposure to the sugar up to 10 minutes (Fig. 5). Since this was consistent with the view that the inhibition was a function of the amount of sugar previously absorbed by the tissue, it was reasoned that varying the concentration of galactose in a fixed incubation time should produce varying degrees of inhibition of cycloleucine uptake. Such is indeed the case. Preincubation of tissue for 10 minutes in concentrations of galactose ranging from to 24 mM produced inhibitions of varying intensity up to a maximum attained at about 4 mM (Fig. 6). Such an attainment of a maximum would be expected in a short fixed time period if the inhibition is dependent on the amount of sugar absorbed and if sugar absorption follows saturation kinetics. At this point the data seemed to indicate that absorption of galactose affected subsequent uptake of an amino acid but did not allow any conclusion as to whether. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
