Effects of metamorphosis on blood respiratory properties and erythrocyte adenosine triphosphate level of the salamander dicamptodon ensatus (Eschscholtz)

Abstract

Hemoglobin properties, erythrocyte ATP concentration and blood lespiratory properties were investigated in larval and adult forms of the urodele, Dicamptodon ensatus. The hemoglobin of both forms eluted as a single peak on Sephadex G-75 (app mol wt = 66000) and was heterogeneous electrophoretically. The major fraction migrated anodal to Hb A in larvae and cathodal to Hb A in adults. After metamorphosis there were significant increases in hematocrit (20.9 to 24.2 %) and hemoglobin concentration (3.8 to 4.4 g%) but no change in mean corpuscular hemoglobin concentration (18.3%). There was no significant change in the Bohr factor (−0.131 to−0.139) or temperature factor ( Δlog P 50/ ΔT = −0.032 to −0.029). Buffer capacity increased slightly from 8.0 to 9.3 ΔmM HCO 3 −/L/Δ pH. The oxygen affinity of purified (phosphate free) larval and adult hemoglobin solutions was similar and, in both cases, was decreased by the addition of ATP. The erythrocyte ATP concentration of adult blood was significantly higher than that of larval blood (39 μM/g Hb compared with 21 μM/g Hb) and there was a corresponding significant difference in oxygen affinity (P 50 at pH 7.8 and 15°C = 21.9 mm Hg for larval and 31.6 mm Hg for adult blood). This is the first evidence for organic phosphate regulation of oxygen affinity in ectothermic vertebrates. The results are discussed with respect to the increased metabolic rate and the transition from aquatic to aerial respiration accompanying metamorphosis.