Effects of dilazep, theophylline and indomethacin on vascular responses to adenosine compounds and to release of renal arterial occlusion

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Abstract
In anesthetized dogs, intrarenal arterial injections of adenosine (Ads) and AMP caused transient, vasoconstrictions, but those of ADP and ATP caused vasodilations. All of these agents produced marked vasodilations in the mesenteric and femoral vascular beds. An i.v. injection of dilazep (10-30 .mu.g/kg) significantly enhanced the effects of Ads and AMP at these 3 vascular beds, but this compound had no effect on the results with ADP, ATP, norepinephrine and angiotensin. Administration of theophylline (10-30 mg/kg) given i.v. attenuated Ads and AMP actions, but had no effects on the other 4 agents. Renal vasoconstriction induced by Ads, AMP, norepinephrine and angiotensin were followed by slight vasodilations which were abolished by indomethacin (2-5 mg/kg) given i.v. Based on these findings postocclusive renal vascular responses were examined. The responses were divided into 2 phases. Phase1 was the initial decrease and phase2 was the successive gradual increase in renal blood flow (RBF). Phase1 was significantly potentiated by dilazep, but inhibited by theophylline. Phase2 was abolished by indomethacin. The postocclusive renal vascular responses may be mediated through Ads and/or AMP and prostaglandins released from the kidney.