Central control of the cardiovascular and respiratory systems and their interactions in vertebrates

This review explores the fundamental neuranatomical and functional bases fo r integration of the respiratory and cardiovascular systems in vertebrates and traces their evolution through the vertebrate groups, from primarily wa ter-breathing fish and larval amphibians to facultative air-breathers such as lungfish and some adult amphibians and finally obligate air-breathers am ong the reptiles, birds, and mammals. A comparative account of respiratory rhythm generation leads to consideration of the changing roles in cardiores piratory integration for central and peripheral chemoreceptors and mechanor eceptors and their central projections. We review evidence of a developing role in the control of cardiorespiratory interactions for the partial reloc ation from the dorsal motor nucleus of the vagus into the nucleus ambiguus of vagal preganglionic neurons, and in particular those innervating the hea rt, and for the existence of a functional topography of specific groups of sympathetic preganglionic neurons in the spinal cord. Finally, we consider the mechanisms generating temporal modulation of heart rate, vasomotor tone , and control of the airways in mammals; cardiorespiratory synchrony in fis h; and integration of the cardiorespiratory system during intermittent brea thing in amphibians, reptiles, and diving birds. Concluding comments sugges t areas for further productive research.