HEMOGLOBIN-FUNCTION IN A SKIN-BREATHING AQUATIC SALAMANDER, DESMOGNATHUS-QUADRAMACULATUS

Adult black-bellied salamanders (Desmognathus quadramaculatus) were ma intained in humidified gas at 12 degrees C. Hypoxic salamanders were e xposed to 8.1-9.6% O-2 for 10-11 days; normoxic animals were maintaine d in air (20.9% O-2). Hypoxia acclimation had no effect on blood O-2 a ffinity, O-2 equilibrium curve shape or CO2 Bohr effect. At pH 7.7, P- 50 values for hypoxic and normoxic salamanders were 28.2 +/- 0.4 and 2 8.6 +/- 0.8 Torr, respectively. Hill plots were curvilinear for both t reatments; Hill's n increased from values of 2.1-2.2 below 40% saturat ion (S) to 2.6 above 50% S. CO2 Bohr slopes (Delta log P-50/Delta pH) were -0.19 +/- 0.01 and -0.23 +/- 0.02 for hypoxic and normoxic animal s, respectively. Resting M(O2) for a separate group of normoxic salama nders fell into two categories; low M(O2) (1.46 +/- 0.16 mu mol.g(-1). h(-1)) and high M(O2) (3.51 +/- 0.52) animals. Exposures to 5 and 25% CO had no effect on M(O2) of low metabolism Desmognathus, but reduced M(O2) of high metabolism animals to levels similar to the low M(O2) gr oup. Hb-O-2 binding results suggest that D. quadramaculatus blood is i deally suited for respiratory O-2 exchange during normoxic activity. W hile submerged and inactive, hypoxic boundary layers surround the skin -breather. Contributions of Hb during hypoxic inactivity may be to aug ment O-2 content and increase blood buffering capacity.