Inhibition of adrenergic proton extrusion in rainbow trout red cells by nitrite-induced methaemoglobinaemia
✍ Scribed by Mikko Nikinmaa; Frank B. Jensen
- Publisher
- Springer-Verlag
- Year
- 1992
- Tongue
- English
- Weight
- 638 KB
- Volume
- 162
- Category
- Article
- ISSN
- 0174-1578
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✦ Synopsis
The effects of nitrite-induced methaemoglobinaemia on adrenergic proton extrusion from rainbow trout red blood cells were studied using the pH-stat method. In control conditions adrenergic proton extrusion was completely inhibited by amiloride and was greater in deoxygenated than in oxygenated erythrocytes. Nitrite-induced methaemoglobinaemia was associated with a pronounced reduction in the catecholamine-stimulated proton efflux from both deoxygenated and oxygenated erythrocytes. In deoxygenated erythrocytes the initial proton efflux upon catecholamine stimulation decreased by 60-70%, while the percentage of methaemoglobin in the red cells increased from the control level of 1-3% to 20%. In oxygenated erythrocytes the decrease was 30% at the same methaemoglobin percentage range. It is suggested that the pronounced influence of nitrite-induced methaemoglobinaemia on adrenergic proton efflux results from an inhibition of the red cell sodium/proton exchanger by the R-like haemoglobin conformations.