Hand MF, Haynes WG, Johnstone HA, Anderson JL, Webb DJ
Erythropoietin enhances vascular responsiveness to norepinephrine in renal failure

Kidney Int (Sep) 48:806-813 1995

Increased blood pressure into the hypertensive range or worsening hypertension after erythropoietin (EPO) therapy in hemodialysis patients is a well recognized clinical phenomenon; however, the mechanism of EPO-induced hypertension remains unknown. Studies evaluating a direct effect of EPO on the vasculature, as well as indirect effects of increased hematocrit, viscosity and various humoral substances have failed to yield a satisfactory mechanism to explain EPO-induced hypertension.

In this study Hand et al hypothesize that the treatment with EPO alters vascular responsiveness to catecholeamines in hemodialysis patients leading to hypertension. They evaluated the forearm vascular response to norepinephrine and endothelin-1 in 9 consecutive ESRD patients (on maintenance hemodialysis for at least 3 months) before and after 12 weeks of EPO. Hematocrit, blood pressure and total peripheral resistance increased significantly after EPO. Forearm vascular resistance response to intraarterial norepinephrine was reduced as compared to healthy controls at baseline, but increased significantly after 6 and 12 weeks of EPO. In contrast the forearm vascular resistance response to endothelin-1 was decreased although not significantly after EPO treatment.

The findings indicate that vascular responsiveness to norepinephrine in anemic hemodialysis patients is abnormally reduced and is restored after EPO therapy and suggest that blood pressure elevation during EPO may be mediated in part through this mechanism. This is an interesting finding. If it is true that an increase in responsiveness to norepinephrine points to the mechanism of EPO-induced hypertension, it would be reasonable to test this hypothesis by use of clonidine or an alpha-blocker as a means of controlling or preventing hypertension in susceptible individuals. (Toto)

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CRF by problem area : Anemia/Erythropoietin/Iron
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