Control of breathing in African lungfish (Protopterus dolloi): A comparison of aquatic and cocooned (terrestrialized) animals

African lungfish, Protopterus dolloi exhibited constant rates of 0, consumption before (0.95 +/- 0.07 mmol kg(-1)h(-1)), during (1.21 +/- 0.32 mmol kg(-1) h(-1)) and after(1.14 +/- 0.14 mmol kg(-1) h(-1)) extended periods (1-2 months) of terrestrialization while cocooned. Although a breathing event in terrestrialized fish consisted of multiple bouts of inspiration and expiration in rapid succession, the mean frequency of pulmonary breathing events was unaltered in the terrestrialized fish (16.7 +/- 1.4 h(-1) versus 20.1 +/- 4.9 h(-1) in the aquatic and terrestrialized fish, respectively). Hypoxia (similar to 20 mmHg) increased the frequency of breathing events by 16 and 23 h(-1) in the aquatic and terrestrialized fish, respectively. Hyperoxia (similar to 550 mmHg) decreased breathing event frequency by 10 and 15 h(-1) in the aquatic and terrestriallized animals. Aquatic hypercapnia (similar to 37.5 mmHg) increased pulmonary breathing frequency (from 15.3 +/- 2.3 to 28.7 +/- 5.4 h(-1)) in free swimming lungfish, whereas aerial hypercapnia was without effect in aquatic or terrestrialized fish. (c) 2007 Elsevier B.V. All rights reserved.