ISSN:
1432-1041
Keywords:
Left ventricular pressure
;
left ventricular contractility
;
hypertension
;
diazoxide
;
beta-adrenergic blockade
;
isometric exercise
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Medicine
Notes:
Summary The effect of diazoxide on left ventricular performance during rest and isometric exercise (handgrip) was examined in 16 unselected hypertensive patients, 6 of whom had been pretreated with the beta-adrenergic blocking agent pindolol. Diazoxide regularly and promptly produced a fall in left ventricular systolic and end diastolic pressures, and an increase in heart rate and left ventricular dp/dtmax. Haemodynamic changes were maximal 2 minutes after injection of the drug and decreased little over the next 8 minutes. After beta-adrenergic blockade, diazoxide caused a more pronounced reduction in left ventricular systolic pressure and a less marked fall in end-diastolic pressure, whilst the diazoxide-induced rise in heart rate was partially and the increase of dp/dtmax was completely inhibited. The increase in systolic pressure during isometric exercise was not influenced by diazoxide, but the positive inotropic reaction was augmented. The findings appear to show that cardiac stimulation by diazoxide is due to a reflex mechanism transmitted by baroreceptors, and that improvement of cardiac performance is mainly due to a reduction of left ventricular after-load.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00562311
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