Objective: The objective of this study was to determine whether the response of renal blood flow (RBF) to adenosine infusions differs between hypertensive patients with and without renal artery stenosis (RAS).
Design and methods: Twenty-one hypertensive patients who underwent diagnostic angiography of the renal arteries were studied. Nine patients (median age 51 years; 45-61 interquartile ranges) were diagnosed as having essential hypertension (EH). Twelve patients (median age 52 years; 50-58) had hypertension and renal artery stenosis. In all patients three stepwise increasing doses of adenosine (1, 3 and 10 (microg/kg/min) were infused into the renal artery. RBF was measured before and during infusions by means of the 133xenon wash-out method. Arterial and venous plasma samples for renin concentration were obtained from the renal artery and renal vein. Intraarterial blood pressure and heart rate were monitored continuously.
Results: Both groups were similar with respect to age, body mass index, mean arterial pressure and baseline RBF (EH: median 428; RAS 343 ml/min/100 g). Both groups showed a similar dose-related increase in RBF during adenosine infusions (normal kidneys: 9, 21 and 34% change vs baseline; stenotic kidneys: 16, 39 and 52% change vs baseline). Ten minutes after discontinuation of the adenosine infusion, RBF returned to baseline in the normal kidney group, but increased further in the stenotic kidney group (71% vs baseline; P = 0.033). Adenosine infusion did not affect the renin secretion in either group.
Conclusion: Both essential hypertensive patients and patients with renal artery stenosis show a dose-dependent vasodilatation following adenosine infusion. This vasodilatation is sustained after discontinuation of the adenosine infusion in patients with renal artery stenosis, suggesting a potentiated mechanism for vasodilatation induced by adenosine.