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Endogenous natriuretic factors: atrial natriuretic hormone and digitalis-like substance in Cushing's syndrome
P Soszynski1, J Slowinska-Srzednicka, A Kasperlik-Zaluska
1Department of Endocrinology, Medical Centre for Postgraduate Education, Warsaw, Poland.
Insights
Chronic hypercortisolaemia increases atrial natriuretic hormone (ANH) levels but does not significantly alter digitalis-like substance (DLS) activity. Neither factor appears directly linked to hypertension in Cushing's syndrome.
Area of Science:
- Endocrinology
- Cardiovascular Physiology
- Hypertension Research
Background:
- Chronic hypercortisolaemia, associated with Cushing's syndrome or high-dose prednisone, can lead to hypertension.
- Endogenous natriuretic factors, including atrial natriuretic hormone (ANH) and digitalis-like substance (DLS), play roles in regulating blood pressure and fluid balance.
Purpose of the Study:
- To investigate the impact of chronic hypercortisolaemia on plasma ANH levels and DLS activity.
- To determine the relationship between these natriuretic factors and hypertension in patients with Cushing's syndrome.
Main Methods:
- Studied 28 patients with Cushing's syndrome and 6 on high-dose prednisone.
- Measured plasma ANH levels and DLS activity (radioimmunoassay, [3H]ouabain binding, 86Rb uptake inhibition assay).
- Correlated factor levels with mean arterial pressure.
Main Results:
- Plasma ANH levels were elevated in Cushing's patients and further increased in prednisone-treated patients compared to controls.
- DLS activity and plasma levels were not significantly altered by hypercortisolaemia, though a slight decrease in erythrocyte 86Rb uptake inhibition was observed in Cushing's patients.
- Only cortisol levels correlated with mean arterial pressure; ANH and DLS did not show a direct relationship with hypertension.
Conclusions:
- Chronic excess of endogenous or exogenous glucocorticoids elevates plasma ANH levels.
- Glucocorticoid excess does not substantially affect DLS activity or plasma levels.
- Neither ANH nor DLS is directly responsible for hypertension in Cushing's syndrome.
Abstract:
In order to investigate the effect of chronic hypercortisolaemia on endogenous natriuretic factors (atrial natriuretic hormone (ANH) and the Na+/K+ pump inhibitor) digitalis-like substance (DLS), and their relation to hypertension, 28 patients with pituitary- or adrenal-dependent Cushing's syndrome and six patients on high-dose prednisone treatment were studied. Plasma ANH levels were increased in patients with Cushing's syndrome (36.0 +/- 1.4 (S.E.M.) ng/l) compared with those in healthy controls (28.6 +/- 1.3 ng/l, P less than 0.01). In prednisone-treated patients, ANH levels (43.8 +/- 4.5 ng/l) were higher than those in patients with Cushing's syndrome and in controls (P less than 0.05 and P less than 0.01 respectively). DLS measured by radioimmunoassay and binding of [3H]ouabain to erythrocytes was not altered in patients with hypercortisolaemia. Slightly decreased DLS activity in the erythrocyte 86Rb uptake inhibition assay was found in patients with Cushing's syndrome (52.9 +/- 2.7%) compared with that in controls (60.9 +/- 1.8%, P less than 0.02). With the exception of cortisol (r = 0.52, P less than 0.01), none of the other factors determined correlated with the mean arterial pressure in patients with Cushing's syndrome. Thus, a chronic excess of endogenous and exogenous glucocorticoids increases plasma levels of ANH, but does not substantially influence DLS activity or plasma levels. Neither natriuretic factor is directly related to hypertension in Cushing's syndrome.