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Michel B. Vallotton, Ulrich Merkelbach and Rolf C. Gaillard

Abstract. The aim of this study was to assess the influence of hormones known to regulate fluid and electrolyte balance on the release of antidiuretic hormone induced by raising serum osmolality.

The stimulus provoked by the infusion of a 2.5% NaCl solution induces an increase of urinary [arginine-8]vasopressin from 1.12 to 2.64 ng/h in men and from 1.65 to 7.27 ng/h in women as has been previously reported. These results were compared to those obtained in males infused with angiotensin II (All) before and during a hypertonic sodium load and in males infused with hypertonic saline on the fourth day of administration of ethinyl-oestradiol. During the combined infusion of All and then hypertonic saline, the mean hourly urinary excretion of AVP increased from 2.8 to 5.67 ng/h. Within each group the increase of urinary AVP was highly significant. The rise of urinary AVP during All infusion was significantly different from the rise observed both in untreated males and untreated females, lying in between. The mean hourly excretion rate of AVP increased before and after hypertonic saline loading from 2.65 to 5.3 ng/h in males pre-treated with ethinyl-oestradiol. The significant difference observed between males and females is reduced when males treated with oestrogen were compared to female subjects. In each group plasma renin activity decreased to low values during the salt-loading test. During oestrogen treatment PRA and plasma renin substrate rose, while urinary aldosterone remained almost unchanged.

We conclude that All stimulates the release of AVP in males and potentiates the response of AVP to the osmolar stimulus, and that oestrogen potentiates in man the release of AVP in response to the osmolar stimulus. This oestrogenic effect may account for the observed sex difference.

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Rolf C. Gaillard, Anne M. Riondel, Charles A. Favrod-Coune, Michel B. Vallotton and Alex F. Muller

Abstract. Prolonged ACTH administration produces a transient and self-limiting stimulation of aldosterone secretion which has been attributed to sodium retention, to inhibition of final enzymatic steps of aldosterone biosynthesis and/or to a morphological change of the glomerulosa cells.

This study was undertaken to determine the possible role of the renin-angiotensin system in mediating the aldosterone escape to repeated ACTH stimulation. We studied in normal male volunteers the effect of a 4 day ACTH administration on urinary aldosterone metabolite excretion (3 oxo-conjugate and tetrahydroaldosterone) during concomitant diuretic administration (spironolactone or triamterene). In addition the plasma aldosterone response to acute iv stimulation with ACTH before and during the corticotrophin-induced 'refractory state' was examined both on normal and on low sodium diet.

Spironolactone was unable to counteract the sodium retention induced by ACTH stimulation; aldosterone excretion showed the same transient increase as with ACTH alone while plasma renin activity remained low. Triamterene produced a negative sodium balance, a significantly more sustained increase in aldosterone excretion and an increase in plasma renin activity. In either situation the two metabolites of aldosterone showed the same pattern of excretion.

The plasma aldosterone response to acute iv ACTH stimulation was completely blocked during the corticotrophin-induced 'refractory state' on normal sodium intake, whereas on low sodium diet a clear-cut response was still obtained.

These data suggest that the transient effect of ACTH on aldosterone secretion is dependent on the state of activity of the renin-angiotensin system. When renin was stimulated by low sodium intake or sodium depletion, the aldosterone response to repeated ACTH administration was more sustained, and when renin was stimulated by low sodium intake, the aldosterone response to acute ACTH was maintained.

In conclusion we suggest that the renin-angiotensin system is able to delay but not to suppress the changes induced in the zona glomerulosa by prolonged ACTH stimulation.

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Anne M. Riondel, Piera Rebuffat, Giuseppina Mazzochi, Gastone G. Nussdorfer, Rolf C. Gaillard, Liliane Bockhorn, Jürg Nussberger, Michel B. Vallotton and Alex F. Muller

Abstract. To test the hypothesis that the trophic action of angiotensin II on the adrenal zona glomerulosa may allow a sustained stimulation of aldosterone by ACTH by preventing the morphological changes of the zona glomerulosa cells into zona fasciculata-like elements we investigated the effects in rats of a 6-day treatment with ACTH (100 μg/kg/day) alone or combined with angiotensin II (300 ng/kg/day) on corticosterone and aldosterone production and adrenal morphology. The responsiveness of both steroids to an acute ACTH dose was also studied on the last day of long-term treatment. Morphologic data showed that prolonged ACTH treatment stimulated the growth of zona glomerulosa cells, though it transformed the tubulo-lamellar cristae of mitochondria into a homogeneous population of vesicles. Angiotensin II furthered the trophic effects of ACTH but prevented the mitochondrial transformation. Despite its ability to conserve the well differentiated aspect of the zona glomerulosa cells, the administration of angiotensin II was unable to prevent the fall in the secretion of aldosterone caused by chronic ACTH treatment and its subsequent unresponsiveness to ACTH stimulation.

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Rolf C Gaillard, Anders F Mattsson, Ann-Charlotte Åkerblad, Bengt-Åke Bengtsson, José Cara, Ulla Feldt-Rasmussen, Maria Kołtowska-Häggström, John P Monson, Bernhard Saller, Patrick Wilton and Roger Abs

Objective

Hypopituitarism is associated with an increased mortality rate but the reasons underlying this have not been fully elucidated. The purpose of this study was to evaluate mortality and associated factors within a large GH-replaced population of hypopituitary patients.

Design

In KIMS (Pfizer International Metabolic Database) 13 983 GH-deficient patients with 69 056 patient-years of follow-up were available.

Methods

This study analysed standardised mortality ratios (SMRs) by Poisson regression. IGF1 SDS was used as an indicator of adequacy of GH replacement. Statistical significance was set to P<0.05.

Results

All-cause mortality was 13% higher compared with normal population rates (SMR, 1.13; 95% confidence interval, 1.04–1.24). Significant associations were female gender, younger age at follow-up, underlying diagnosis of Cushing's disease, craniopharyngioma and aggressive tumour and presence of diabetes insipidus. After controlling for confounding factors, there were statistically significant negative associations between IGF1 SDS after 1, 2 and 3 years of GH replacement and SMR. For cause-specific mortality there was a negative association between 1-year IGF1 SDS and SMR for deaths from cardiovascular diseases (P=0.017) and malignancies (P=0.044).

Conclusions

GH-replaced patients with hypopituitarism demonstrated a modest increase in mortality rate; this appears lower than that previously published in GH-deficient patients. Factors associated with increased mortality included female gender, younger attained age, aetiology and lower IGF1 SDS during therapy. These data indicate that GH replacement in hypopituitary adults with GH deficiency may be considered a safe treatment.