Relationship between cerebro-spinal fluid pH and pulmonary ventilation of the South American lungfish, Lepidosiren paradoxa (Fitz.)

Abstract

The respiratory control in land vertebrates (Tetrapoda) is mainly linked to regulation of acid-base status, which involves peripheral and central chemoreceptors. The lungfish (Dipnoi) might constitute the sister group of all land vertebrates (Tetrapoda) and possess a combination of real lungs and reduced gills. In this context, we evaluated the possible presence of central respiratory chemoreceptors in the South American Lungfish, Lepidosiren paradoxa. Pulmonary ventilation and respiratory frequency increased significantly with reductions of CSF pH by means of mock CSF solutions. This suggests that Lepidosiren possess central acid-base receptors.