CARDIORESPIRATORY SYNCHRONY IN TURTLES

Authors
Citation
T. Wang et Jw. Hicks, CARDIORESPIRATORY SYNCHRONY IN TURTLES, Journal of Experimental Biology, 199(8), 1996, pp. 1791-1800
Citations number
30
Categorie Soggetti
Biology
ISSN journal
00220949
Volume
199
Issue
8
Year of publication
1996
Pages
1791 - 1800
Database
ISI
SICI code
0022-0949(1996)199:8<1791:CSIT>2.0.ZU;2-#
Abstract
Many reptiles, particularly diving species, display characteristic car diovascular changes associated with lung ventilation (cardiorespirator y synchrony), Previous studies on freshwater turtles show that heart r ate and pulmonary blood flow rate (Q(pul)) increase two- to fourfold d uring ventilation compared with breath-holding, and some studies repor t concomitant decreases in systemic blood flow rate (Q(sys)). The prim ary aim of this study was to provide a detailed description of cardior espiratory synchrony in free-diving and fully recovered turtles (Trach emys scripta), During breath-holds lasting longer than 5 min, Q(pul) a veraged 15 ml min(-1) kg(-1) and increased more than threefold to a ma ximum value of 50 ml min(-1) kg(-1) during ventilation. Q(sys), also i ncreased during ventilation compared with during breath-holds lasting longer than 5 min (from 44 to 73 ml min(-1) kg(-1) during ventilation) . Neither Q(pul) nor Q(sys) was affected by the number of breaths in t he ventilatory periods, Changes in Q(pul) and Q(sys) were accomplished entirely through a significant increase in heart rate during ventilat ion, while total stroke volume (systemic + pulmonary) remained constan t, Irrespective of the ventilatory state, Q(sys), exceeded Q(pul) by 2 0-30 ml min(-1) kg(-1). Nevertheless, because Q(pul) increased relativ ely more than Q(sys), during ventilation, Q(pul)/Q(sys) increased from 0.29 during apnoea to 0.80 during lung ventilation. This study confir ms cardiorespiratory synchrony in the turtle Trachemys scripta but, in contrast to earlier studies, a net right-to-left cardiac shunt prevai led regardless of ventilatory state.