Simultaneous apnoea and bradycardia in the lobster <i>Homarus americanus</i>

Abstract

Periods of simultaneous apnoea and bradycardia lasting for up to 20 min have been recorded from specimens of Homarus americanus isolated under experimental conditions but otherwise exposed to no direct stress. The onset of the response and the resumption of normal activity occurred abruptly and simultaneously in both respiratory and circulatory parameters. A study of the response leads the authors to propose a central control area which can inhibit both branchial and cardiac pumps simultaneously. Blood oxygen tensions were monitored during the response and possible mediating effects of oxygen are discussed.