F. Rioux et al., RECOMBINANT HUMAN HEMOGLOBIN (RHB1.1) SELECTIVELY INHIBITS VASORELAXATION ELICITED BY NITRIC-OXIDE DONORS IN RABBIT ISOLATED AORTIC RINGS, Journal of cardiovascular pharmacology, 25(4), 1995, pp. 587-594
We investigated the effect of a genetically engineered recombinant hum
an hemoglobin (rHb1.1), specially designed to be used as a blood subst
itute, on the ability of various well-known vasodilators to relax the
rabbit isolated aortic rings precontracted with the alpha-adrenoceptor
agonist phenylephrine (PE) or with KCl (for nifedipine only). The vas
orelaxant effects of nitroglycerin (NTG) and of sodium nitroprusside (
SNP), two nitrovasodilators whose effects are mediated by nitric oxide
(NO), were inhibited in a concentration-dependent manner by rHb1.1 (1
.5 and 15 mu M). Those elicited by isoproterenol, papaverine, histamin
e, adenosine, atriopeptin II, hydralazine, nifedipine, and cromakalim
were comparatively little affected or not affected by rHb1.1 (15 mu M)
. The ability of captopril to inhibit the vasoconstrictor action of an
giotensin I (AT(1)) in the rabbit aortic rings was not reduced by rHb1
.1 (15 mu M). Our results suggest that rHb1.1 shares with purified hum
an Hb the ability to inhibit selectively the vasorelaxant effect of NO
-releasing substances such as NTG and SNP. Because the targeted plasma
concentration of rHb1.1, when used as a blood substitute, is greater
(similar to 50 times) than the highest concentration of rHb1.1 used in
this study, significant drug interactions can be predicted between NO
donors and rHb1.1.