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Cytosol preparations obtained from 9 different human renal cell carcinomas were investigated for the eventual presence of progestin-binding inhibitors which might offer an explanation for the previous failure to demonstrate high receptor levels in the tumour tissue. The inhibitory potency of these preparations was estimated by measuring the decrease of R 5020 binding to uterine progestin receptors in the presence of tumour cytosol. Interestingly, cytosol from human renal cell carcinoma was found to contain progestin-binding inhibitors. The average inhibition of R-5020-receptor interaction amounted to 46%. In only 1 out of 9 cases, binding was completely suppressed. In order to circumvent the inhibitory reaction potentially occurring in cell-free systems, R-5020-binding studies additionally were performed in cell suspension. Out of 7 carcinomas studied using this assay system, 5 did not contain any specific progestin-binding entities. In 1 tumour, receptor-atypical non-saturable binding was observed. Only in isolated cells prepared from 1 other carcinoma, could slight indications for the presence of low concentrations of progestin receptors be detected.

Biopsies of 9 testicular tumors were examined for the presence of cytoplasmic receptor proteins for estrogens, progestins, androgens, and glucocorticoids. Using an arbitrary threshold value of 10 fmol/mg cytosol protein for a postive assay, only 1 of 9 tumors was estrogen-receptor positive. However, no receptor-specific 8S binding could be detected by low salt sucrose gradient centrifugation. 1 tumor was progesterone-receptor positive. No androgen receptors could be demonstrated. In contrast, 8 of 9 neoplasms contained significant quantities of glucocorticoid receptors exclusively sedimenting at 8S. Our findings suggest that androgens, estrogens, and progestins are unlikely to play a major role in the natural history of testicular tumors. The presence of glucocorticoid receptors might offer a chance for endocrine manipulation of the development and growth of these neoplasms by glucocorticoids.

An enzymatic method is described for isolating intact parenchymal cells from rat livers. 3--4 g cells (wet weight) could be isolated from livers of rats weighing 180--230 g. After an in vitro preperfusion of 15 minutes with a Ca-free buffer, collagenase (200 mg/1) and calcium chloride (5.2 mmol/1) were added. Perfusion was continued for another 15 minutes at 37 degrees C. Micromorphological integrity of cell membranes was demonstrated by scanning electron microscopy. With regard to rates of gluconeogenesis and protein synthesis, parenchymal cells isolated according to our method were found to be superior to liver slices and cells isolated by other methods. Ratios of ATP/ADP (5.69) and of lactate/pyruvate (8.64) as parameters of the energetic situation and the redox state resp. were found within the physiological range. Integrity of cell surface receptors was proved by their sensitivity to epinephrine, glucagon and insulin. Glucagon (0.3 mumol/1) and epinephrine (1 mumol/1) and reduced glycogen deposition in hepatocytes of fasted rats by 84.9 % and 95.9 % resp. Both hormones stimulated glycogenolysis in parenchymal cells of fed rats to a similar extent. Urea synthesis was stimulated 29.5 % by glucagon (1 mumol/1), and inhibited 28.0 % by insulin (10 nmol/1). The stimulatory effect of glucagon (1 mumol/1) was abolished by insulin (10 nmol/1).