Abstract
From the results reported it is evident that the effect of diazoxide is mediated by
influencing the adrenergic system. The metabolic and circulatory effects of diazoxide
are similar to those which can be observed under the influence of epinephrine: Decrease
in serum immunoreactive insulin, increase in blood glucose and impaired glucose tolerance,
increase in plasma free fatty acids, tachycardia, and widened pulse pressure. If one
assumes that the well-known circulatory and metabolic effects of diazoxide are mediated
by influencing the adrenergic system it can be exspected that these effects should
change during alpha and beta receptor blockade. It was the purpose of the present
study to evaluate the assumptions mentioned above.
On three healthy persons and one patient suffering from an islet cell adenoma with
hyperinsulinism blood glucose, plasma free fatty acids, serum immunoreactive insulin,
heart rate, and blood pressure were measured before and during oral administration
of diazoxide.
The results obtained as a control series in fasting state and under the influence
of an intravenous glucose load were compared with the effects of intravenous phentolamine
infusion and oral administration of propranolol respectively under otherwise the same
conditions. In all cases the diazoxide induced inhibition of insulin secretion and
the impaired glucose tolerance could be reversed by phentolamine. The effects of diazoxide
on plasma free fatty acids and on heart rate and blood pressure, however, were only
inhibited by beta receptor blockade with propranolol.
Zusammenfassung
Bei klinischen Studien konnten unter Diazoxidgaben metabolische und zirkulatorische
Wirkungen beobachtet werden, wie sie weitgehend durch adrenerge Substanzen auslösbar
sind. Dazu gehören Abfall des Seruminsulins, verminderte Glucosetoleranz, Anstieg
der freien Fettsäuren und Tachykardie. Die metabolischen und zirkulatorischen Veränderungen
durch Diazoxid konnten bei den klinischen Untersuchungen durch Gaben von alpha- und
beta-Rezeptorenblockern weitgehend aufgehoben werden. Diese Untersuchungsergebnisse
weisen darauf hin, daß der Wirkungsmechanismus von Diazoxid in einer Beeinflussung
des adrenergen Systems liegt.
Key words
Diazoxide - Adrenergic System - Immunoreactive Insulin - Glucose Tolerance - Islet
Cell Adenoma
1 Die Untersuchungen wurden von der Deutschen Forschungsgemeinschaft unterstützt.
