Radioactive myo-inositol was injected intraperitoneally into nephrectomized rats. The radioactive material present in liver, spleen, brain, heart, diaphragm, seminal vesicle, coagulating gland, prostate, epididymis, vas deferens and testis was shown to consist exclusively of myo-inositol and its derivatives, as shown by paper chromatography of hydrolysates and trichloroacetic acid extracts of these tissues. Radioactive myo-inositol was accumulated rapidly within 1 h by the thyroid, coagulating gland and seminal vesicle. Other tissues, such as the pituitary, prostate gland, liver and spleen, concentrated myo-inositol less actively. The muscle tissues studied (diaphragm and heart) concentrated little inositol, whereas brain, testis, and epididymal fat-pad did not concentrate it at all. The lipid fraction of liver contained most of the radio-labelled myo-inositol. In the other organs most of the radioactivity was found in the aqueous trichloroacetic acid extract, largely as free myo-inositol.

3bound to the membrane (in that it resists washing out by the normal flow of secretions). A firmly bound effect was therefore sought by exposing normal red cells to saliva for 5 min, and then washing, before measuring ouabain-insensitive efflux. Table 2 shows that there was no difference between cells exposed to saliva and then washed, and cells not exposed to saliva. No firmly bound factor was demonstrated.The significance of humoral substances affecting membrane transport remains to be clarified. There does not appear to be any known hormone, for example, which could easily explain the above effect of saliva, whereas simple physical or physicochemical factors would seem to be excluded by the experimental controls. Modification of the cell membrane by uncharacterized circulating or secreted factors may have a bearing on transport processes in general, and possibly on the disturbance of CF in particular. However, the red cell model, as used in this study, has not confirmed that such a mechanism is important in CF. CONCLUSIONIn a preliminary study, the red blood cells of patients with cystic fibrosis were found to show decreased ouabain-insensitive Na+ efflux. The ouabain-sensitive Na+ efflux, total Na+ efflux, and Na+ influx were found to be normal. This information was used to guide the choice of transport parameters in the main study. The effect of cystic fibrosis saliva on normal red cells was not significantly different from that of control saliva, but both Pediat. Res. 12: 3-6 (1978) normal saliva and cystic fibrosis saliva appear to contain a substance which accelerates Na+ transport in the red cell.

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A procedure is described for evaluating the uptake of myo‐inositol by measuring the radioactivity (dpm/mg wet weight of tissue) in the male reproductive accessory glands after injection of (2‐3H)myo‐inositol into bilaterally nephrectomized rats. The rate of secretion of the labelled inositol was assessed by measuring the total dpm in fluids expressed from the seminal vesicles and coagulating glands after injection of the tritiated inositol. Cyproterone acetate treatment (15 mg/day), for 2 to 7 days, inhibited secretion of radioactive inositol by the seminal vesicles and decreased the uptake capacity to a greater extent than it inhibited the rate of inositol accumulation into these glands. It had a similar effect on the coagulating glands after 7 days of treatment. The prostate was the least affected by the cyproterone acetate treatment.

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