Prostaglandins participate in the renal vasodilation due to hydralazine in dogs.
The authors studied the effects of bolus injections of hydralazine (500 micrograms) into the renal artery of chloralose-anesthetized dogs. In control dogs, hydralazine injection resulted in an increase in renal artery blood flow of 110 +/- 10.4 ml/min (53 +/- 4.7%) from 214 +/- 28 ml/min. In dogs that were pretreated with the alpha-1 adrenergic antagonist, prazosin (1 mg/kg), hydralazine injection increased renal blood flow by 95 +/- 22 ml/min (37 +/- 7.4%) from 253 +/- 19 ml/min, an increase not different from that found in control dogs. However, in dogs pretreated with indomethacin (5 mg/kg) or sodium meclofenamate (3 mg/kg), inhibitors of cyclooxygenase, hydralazine injection resulted in an increase in renal artery blood flow of only 44 +/- 5.3 ml/min (19 +/- 2.7%) from 235 +/- 23 ml/min, an increase significantly different from that in control dogs (P less than .05). The renal blood flow response to hydralazine injection developed slowly, reached a maximum in 20 min and was maintained for at least 1 hr. Arterial blood pressure, heart rate and descending aortic blood flow were not significantly changed after hydralazine injection. The authors conclude that hydralazine increases renal blood flow in dogs by a mechanism independent of alpha-1 adrenergic receptors and that this increase is, in large part, mediated by prostaglandin release.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D016861:Cyclooxygenase Inhibitors; D004285:Dogs; D006830:Hydralazine / Q000494:pharmacology*; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D011224:Prazosin / Q000494:pharmacology; D011453:Prostaglandins / Q000502:physiology*; D012079:Renal Circulation / Q000187:drug effects*; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*
D016861:Cyclooxygenase Inhibitors; D011453:Prostaglandins; D006830:Hydralazine; D011224:Prazosin; D007213:Indomethacin