Oxygen sensitive chemoreceptors in the first gill arch of the tadpole,Rana catesbeiana

Spike frequency was recorded in the nerve of the isolated superfused first gill arch of the bullfrog larva, Rana catesbeiana and the response to different superfusate [Formula: see text] was evaluated. In the metamorphic tadpole, spike frequency increased significantly when the superfusate [Formula: see text] was decreased (mean ± SEM): 8.5 ± 1.6 Hz at 650 Torr, 11.7 ± 1.9 Hz at 140 Torr, 13.3 ± 1.8 Hz at 65 Torr, 14.8 ± 2.4 Hz at 0 Torr (ANOVA, p = 0.0002). The O2sensitive chemoreceptor stimulants NaCN and almitrine also increased the spike frequency. This study demonstrates the presence of O2sensitive chemoreceptors in the first gill arch of the tadpole.Key words: tadpole, Rana catesbeiana, gill, chemoreceptor, oxygen.