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J. Müller and F. Gross

ABSTRACT

Aldosterone biosynthesis by quartered adrenal glands from rats with different forms of experimental renal hypertension due to clamping of one renal artery, was studied under various in vitro conditions. During incubation without aldosterone-stimulating substances, the adrenals of rats with one renal artery clamped and the other kidney left intact produced 200 % more aldosterone from endogenous precursors and converted 50 % more added tritium-labelled pregnenolone, progesterone or corticosterone to aldosterone than adrenals of control animals. The difference in aldosterone production was less marked when serotonin, KCl or ACTH was added to the incubation medium. The production of corticosterone and of deoxycorticosterone, respectively, was almost the same in adrenals of both groups of rats under most in vitro conditions. The marked rise in aldosterone production seen in the presence of an intact contralateral kidney was partially or completely inhibited, when simultaneously with renal artery constriction, the contralateral kidney was removed or the ureter of either the clamped or the contralateral kidney was ligated. These results indicate that in rats with experimental renal hypertension, increases in aldosterone production are correlated with increases of plasma renin activity and of the renin content of the clamped kidney, but are independent of changes in blood pressure. Since chronically elevated levels of plasma or renal renin activity act mainly in the early stages of aldosterone biosynthesis, it is concluded that the marked activation in the final stages of aldosterone biosynthesis observed in sodium deficiency is not mediated by the renin-angiotensin system.

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Manfred J Müller

In the article by Iossa and coworkers, published in this issue (1), the authors studied energy and fat balance in response to an energy dense (i.e. a fat rich) or a low fat diet in hypothyroid rats. The major finding of the study was that eating more fat results in disproportional fat deposition and weight gain in hypothyroidism. This study provides a further aspect of the action of thyroid hormones on energy and macronutrient balance. The data also correspond to the clinical experience of weight gain associated with hypothyroidism. They support the value of a low fat diet.

Overfeeding in healthy man results in a positive energy balance and, thus, weight gain. Surplus fuels during energy surfeit are mainly stored as fat in adipose tissue. One of the important findings that came out of the Vermont study (2) on the effects of long-term overeating was that lean subjects had difficulty

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H.-J. Sehrbundt and W. Müller

ABSTRACT

The dry mass of the cells of a chromophobic, eosinophilic and basophilic adenoma of the pituitary gland is calculated with the use of a Zeiss interference microscope. The dry weights per unit area of the eosinophilic cells are the largest, followed by the chromophobic and the basophilic. The dry weights are compared with the activity of the cells. The errors based on the method are discussed.

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B. VON SCHÜTZ and M. J. MÜLLER

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U. Müller, Th. Bauknecht and J. W. Siebers

Abstract.

The increase in the number of the ovarian LH/hCG-receptors and of serum progesterone concentration during pregnancy in the rat is highly dependent on the presence of prolactin during the luteinization process. Blocking of the hypophyseal prolactin secretion by twice daily injections of 2 μg/g body weight bromocriptine into rats from the first day of pregnancy onwards prevents the increase in ovarian hCG-binding and progesterone production. Similar results are obtained by application of bromocriptine during the first three days only or either at day 1, 3 or 5 after mating. In all bromocriptine treated rats implantation of blastocysts does not occur. The failure to implant is not due to a teratogenic effect of bromocriptine onto preimplantation embryos, but is probably the consequence of changes of the uterine mucosa caused by the lack of progesterone production in the luteal cells.

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M. J. MÜLLER, P. HUNZINGER, U. PASCHEN and H. J. SEITZ

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J. Hertoghe, J. Crabbé, A. Duckert-Maulbetsch and A. F. Muller

The colorimetric reaction described by Porter & Silber (1950) is based on the dihydroxy-ketone side chain of the 17-hydroxycorticoids. Among several methods for determination of these steroids by means of this reaction. the method of Reddy et al. (1952) is particularly interesting, because of its simplicity which is mostly due to the fact that conjugated as well as free 17-hydroxycorticoids can be simultaneously extracted with n-butanol alcohol.

Recently, Reddy (1954) has proposed a modification of his method, further improving the rapidity and the reliability of the determinations. The outline of his new technique is briefly recalled: from crude urine acidified to pH 1 and saturated with solid sodium sulphate, the 17-hydroxycorticoids are extracted with butanol v/v. The butanol extract is treated with solid sodium carbonate before being used for the colorimetric reaction of Porter and Silber. performed as follows: one ml. of extract is added to 4 ml. of the

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K. Sinterhauf, T. Müller, H. J. Spira, D. Müller and D. Lommer

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G. HILDEBRANDT, J. ZIERSKI, H. MÜLLER, H. MÜLLER, H. STRACKE, H. SCHATZ and R. WILKENS