Blood flow and volume distribution during forced submergence in Pekin ducks (Anas platyrhynchos)

Abstract

HEIEIS, M. R. A., and JONES, D. R. 1988. Blood flow and volume distribution during forced submergence in Pekin ducks (Anas platyrhynchos). Can. J. Zool. 66: 1589 -1596. Blood is the major oxygen store in ducks forced to dive, and underwater endurance depends on how much of this store can be used by oxygen-sensitive tissues such as the heart and brain. Arterial injection of macroaggregated albumin labelled with technetium-99m, which is trapped and held by capillaries, showed that circulation in dives was restricted to the thoracic and head areas. However, tracing red blood cells labelled with technetium-99m as they were injected during dives showed not only that the time required for the activity to reach equilibrium was 4-10 times longer than when labelled cells were injected into resting ducks but also that blood flow continued in the leg and visceral regions. Tracing red blood cells, labelled with technetium-99m and mixed in the circulation before a dive, during the dive showed that labelled red blood cells were redistributed from the peripheral and visceral areas to the central cardiovascular area. Measurement of circulating red blood cell volume during and after diving showed that, on average, 75.24 f 4.56% of the total red blood cell volume was circulated during forced submergence. Hence, in forced dives, red blood cell volume is positioned in such a manner that the heart and brain have access to the oxygen stored there, and the residual blood flow in the periphery ensures that most of the red blood cell volume is circulated.HEIEIS, M. R. A., et JONES, D. R. 1988. Blood flow and volume distribution during forced submergence in Pekin ducks (Anas platyrhynchos). Can. J. Zool. 66 : 1589 -1596. Le sang est la principale source d'oxygttne durant la plongie forcCe chez le canard. L'endurance a la submersion depend de la proportion d'oxygttne utilisCe par les tissus sensibles a l'hypoxie, tels le cerveau et le coeur. Des injections arterielles de macro-agrkgats d'albumine marques au technetium-99 m et retenus dans les capillaires semblent montrer que la circulation durant la plongee est restreinte aux regions thoraciques et cerebrales. Cependant, l'observation suivie des erythrocytes marques au technCtium-99 m et inject& au cours de la plongee montre, non seulement que le temps requis pour que leur activite atteigne un equilibre est 4 a 10 fois plus long que lorsque les agrkgats sont injectes chez les canards au repos, mais aussi que le sang continue de circuler dans les pattes et les rCgions viscCrales. L'observation suivie des erythrocytes marques au technetium-99 m et integres a la circulation avant la plongee montre que ces Crythrocytes sont redistribuks des regions peripheriques et viscCrales a la region cardiovasculaire durant la plongee. La mesure du volume des erythrocytes en circulation durant et aprks les submersions forcies indique qu'en moyenne 75,24 f 4,56% du volume total des Crythrocytes circule durant la plongie forcCe. Durant la plongee forcee, le volume d'Crythrocytes est donc reparti de manikre a...

The rostral ventrolateral medulla mediates the sympathoactivation produced by chemical stimulation of the rat nasal mucosa

“…Since the sympathoexcitatory neurons of the RVLM are believed to be organized in an organ‐specific pattern (McAllen, 1986; McAllen & Dampney, 1990; McAllen et al . 1995), this result supports the notion that nasal stimulation activates sympathetic outflow differentially according to the vascular bed, as suggested by blood flow studies in awake animals (Zapol et al 1979; Heieis & Jones, 1988; Ollenberger et al 1998).…”

“…Generally, peripheral vasoconstriction is selectively increased so that there is a redistribution of cardiac output away from hypoxia-tolerant tissues. Fractional blood flow decreases to skeletal muscle, liver, spleen, intestines and other tissues that are capable of withstanding a temporary period of hypoxia (Zapol et al 1979;Heieis & Jones, 1988;Ollenberger et al 1998). In contrast, cerebral blood flow increases or remains nearly constant, and myocardial blood flow is reduced in proportion to the decrease in cardiac work that results from the bradycardia (Blix et al 1976;Zapol et al 1979;Yu & Blessing, 1997).…”

“…Fractional blood flow decreases to skeletal muscle, liver, spleen, intestines and other tissues that are capable of withstanding a temporary period of hypoxia (Zapol et al . 1979; Heieis & Jones, 1988; Ollenberger et al . 1998).…”

Blood Flow Distribution in Submerged and Surface-Swimming Ducks

“…In general, heart rate, blood pressure and relative blood flow measured in resting, swimming and forced diving ducks corroborated the findings of previous studies in ducks (Johansen, 1964;Jones etal. 1979;Heieis and Jones, 1988). The 99m Tc-MAA imaging technique provided a clear visual demonstration that perfusion of the active hindlimb muscles increased during surface swimming (Fig.…”

“…1988), and the forced dive response, in which hypoxia-tolerant tissues, including the skeletal muscles, are rendered ischaemic (Johansen, 1964;Butler and Jones, 1971;Jones etal. 1979;Heieis and Jones, 1988). This raises a question about blood flow in the locomotory muscles during active unrestrained dives: do these muscles receive a reduced blood supply, as in the forced dive response, or are they continuously perfused, as during surface swimming?…”