Coronary resistance increase by nondefatted albumin in saline-perfused rabbit hearts

In isolated hearts perfused with salt solutions, albumin is often added in low concentrations for preservation of endothelial function. Albumin in low concentrations is also sometimes used as an intravascular indicator in such preparations. We perfused isolated rabbit hearts according to Langendorff with a constant flow of Tyrode solution. Despite maximal vasodilation with 10 microM adenosine, coronary vascular resistance increased by 14% after 0.3 g/100 ml nondefatted bovine serum albumin (Sigma A-9647) was added to the perfusate compared with the control resistance with no albumin present. The 50% response time for the vasoconstrictive response to the step change in albumin concentration was 20 +/- 13 s (mean +/- SD). When 0.3 g/100 ml of defatted albumin (Sigma A-6003) was added, the resistance increase was only 1.4% and is explained by increased viscosity. Vasoconstrictive effects of certain nondefatted albumin preparations must be taken into account by investigators who perfuse organs with albumin-containing solutions.