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  1. 1.

    Recta of Schistocerca gregaria possess a high-affinity (Kt = 10 mmol 1−1) and high-capacity (Vmax = 4.2 μequiv cm−2h−1) active absorptive mechanism for proline second in magnitude only to stimulated Cl transport.

  2. 2.

    Transcellular and paracellular pathways have extremely low passive permeability to proline, resulting in very high flux ratios (40:1) compared with those for other.solutes (less than 6:1).

  3. 3.

    Net epithelial transport of proline is largely independent of luminal Na+, K+ and Cl. Sodium influx does not change when proline net fluxes are varied 14-fold. Therefore Na+ cotransport is not a principal mechanism of proline uptake in this tissue.

  4. 4.

    Prolonged absence of Na+ and K+ from the haemocoel side partially inhibits proline transport, probably indirectly, by affecting the general transport capacity of the rectum. Inhibition is irreversible.

  5. 5.

    A component of the net proline flux (Jnetpro) is electrogenic, located in the apical membrane, and may be due to proline/proton cotransport.

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