Elevated intra-abdominal pressure limits venous return during exercise in Varanus exanthematicus
Munns, Suzanne L, Hartzler, Lynn K, Bennett, Albert F, and Hicks, James W (2004) Elevated intra-abdominal pressure limits venous return during exercise in Varanus exanthematicus. Journal of Experimental Biology, 207 (23). pp. 4111-4120.
|PDF - Repository staff only - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader|
The effects of treadmill exercise on components of the cardiovascular (venous return, heart rate, arterial blood pressure) and respiratory systems (minute ventilation, tidal volume, breathing frequency, oxygen consumption, carbon dioxide production) and intra-abdominal pressure were investigated in the Savannah monitor lizard, Varanus exanthematicus, at 35ºC. Compared to resting conditions, treadmill exercise significantly increased lung ventilation and gular pumping, intra-abdominal pressure, mean arterial blood pressure and venous return (flow in post caval vein). However, venous return declines at high levels of activity, and mean arterial pressure and venous return did not attain peak values until the recovery period, immediately following activity. Elevating intra-abdominal pressure in resting lizards (via saline infusion) resulted in significant reductions in venous return when the transmural pressure of the post cava became negative (i.e. when intra-abdominal pressure exceeded central venous pressure). Together these results suggest that increments in intra-abdominal pressure compress the large abdominal veins and inhibit venous return. During locomotion, the physical compression of the large abdominal veins may represent a significant limitation to cardiac output and maximal oxygen consumption in lizards.
© The Company of Biologists Ltd 2005
|Keywords:||Exercise, Hemodynamics, Intra-abdominal pressure, Lizard, Locomotion, Oxygen consumption, Reptiles, Venous return, Ventilation|
|FoR Codes:||06 BIOLOGICAL SCIENCES > 0606 Physiology > 060604 Comparative Physiology @ 0%|
06 BIOLOGICAL SCIENCES > 0606 Physiology > 060603 Animal Physiology Systems @ 0%
|Deposited On:||05 Oct 2006|
|Last Modified:||14 Feb 2011 01:26|
Last 12 Months: 0
Repository Staff Only: item control page