Haemodynamic and metabolic effects of diazoxide during rest and forearm exercise

The immediate haemodynamic and metabolic effects of acute dose of diazoxide 300 mg i.v. were studied in six healthy subjects at rest and during dynamic forearm exercise. Control periods of rest, exercise and recovery were compared with corresponding periods after drug administration. Resting forearm blood flow was almost doubled after diazoxide, and during forearm exercise it increased by about 24%. Systolic blood pressure did not change significantly, but diastolic blood pressure was moderately decreased (5-10 mm Hg). The mean heart rate increased from 57 to 92 beats/min immediately after diazoxide administration and remained about 20% higher throughout the study. There was a sustained increase in arterial blood glucose of almost 1 mmol/l. The arterial concentration of free fatty acids increased transiently just after diazoxide and then returned to the pre-drug level. The arterial concentration of triglycerides after diazoxide was decreased by about 15% throughout the study. Arterial blood lactate remained unchanged. Forearm uptake of oxygen and glucose tended to increase during the exercise and recovery periods, whereas lactate release remained unchanged.