Viscosity of deoxygenated haemoglobin-A in response to calcium ions and to 2,3-bisphosphoglycerate

Abstract

Couette device was used for the examination of the flow behaviour exhibited by haemoglobin-A (Hb-A) solutions; the applied shear rates ranged from 0.624 x 10-3 through 4.59 s-1. The degree of O2 - saturation (Soz) was either above 90% (oxyhaemoglobin-A or OxyHb-A) or below 10% (deoxyhaemoglobin­ A or DeoxyHb-A). Besides O2 ; K+, ea2+ and 2,3-bisphosphoglycerate (2,3- BPG) were used as additional effectors of haemoglobin-A Thus, it has been possible to demonstrate: 1) The flow properties of OxyHb-A are strict Newtonian and are independent of any other effector added to the solutions. 2) The reduction of S02 does not alter the linear torque - shear rate relationship as known for OxyHb-A 3) K+ at 0.3 mmol/g Deo~Hb-A does not interfere with the Newtonian behaviour of DeoxyHb-A 4) ea2+ at 4 j.tmol/g DeoxyHb-A has no measurable influence on DeoxyHb-A rheology; at 24 j.tmol/g DeoxyHb-A, however, a fourfold rise in the viscosity of DeoxyHb-A was observed. 5) The addition of 2,3-BPG at fractions of 20 and 30 j.tmol/g DeoxyHb-A led to a 1.4 - fold increase in DeoxyHb-A viscosity for solutions with a DeoxyHb-A concentration below 32 g/100 ml; above 33 g/100 ml, however, the increase was 2.3 - fold if 2,3-BPG was present at the high relative concentration. 6) Micros­ copically, particle formation has been ascertained for the cases of increased viscosity in 4) and 5). This development of heterogeneity proved to be a reversible process on reoxygenation.