Action of hydralazine on glucose turnover and plasma lipids in dogs

Abstract

Acute effects of a single intravenous injection of hydralazine (20 mg./Kg.) on heart rate, femoral arterial blood pressure, glucose turnover (technique of priming injection-continuous infusion of glucose-U-C 14) and plasma lipids and catecholamines were studied in 15 anesthetized dogs. In 6 of the dogs, 3 received isotonic saline solution and 3 received hydralazine diluent. These control dogs had no changes in heart rate, arterial pressure or levels of plasma glucose and FFA. In the others, hydralazine produced significant, prompt and sustained increments in plasma FFA and heart rate and a decrement in diastolic (no change in systolic) blood pressure, the respective mean maximal changes from control levels being 330 Eq./L., 57 x/min., and 26 mm.Hg. Plasma level and rate of appearance (hepatic output) of glucose increased after hydralazine, with a maximum increase in plasma glucose of 58 mg. % above control 2 1 2 hours after injection. Rate of disappearance (tissue uptake) of glucose remained unaltered despite the hyperglycemia. In 3 dogs, high inferior vena cava blood showed marked increases above control levels of both plasma epinephrine and norepinephrine after hydralazine. Plasma cholesterol and triglyceride levels did not change. In conclusion, hydralazine induces hyperglycemia by increasing rate of appearance and by relatively inhibiting rate of disappearance of glucose. The changes in glucose turnover and the noted elevations in plasma FFA and heart rate are paralleled by increased secretion of catecholamines.