Hemodynamic effects of python neuropeptide γ in the anesthetized python, Python regius

Skovgaard, Nini; Galli, Gina L. J.; Taylor, E. W.; Conlon, J. Michael; Wang, Tobias

doi:10.1016/j.regpep.2004.12.016

Cited by 19 publications

(9 citation statements)

References 28 publications

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“…Hemodynamic variables of the anesthetized pythons studied here were similar to previous reports (37,48), and the higher heart rate, compared with recovered and awake pythons (34), is caused by depression of autonomic and barostatic functions during anesthesia. This makes anesthetized animals suitable for studies on local regulatory mechanism, because it is easier to discern the direct effect of the pharmacological manipulation.…”

Section: Vascular Effects Of Histamine In Anesthetized Animalssupporting

confidence: 89%

“…Because the left pulmonary artery was occlusively cannulated, blood flow measurements in the right pulmonary artery represent total pulmonary blood flow (Q pul). In anesthetized pythons, total systemic blood flow (Qsys) can be estimated as 2.5 times left aortic blood flow (QLAo) (37). Total cardiac output (Qtot) was calculated as QsysϩQpul.…”

Section: Data Analysis and Statisticsmentioning

confidence: 99%

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Histamine induces postprandial tachycardia through a direct effect on cardiac H₂-receptors in pythons

Skovgaard¹,

Møller²,

Gesser³

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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The intrinsic heart rate of most vertebrates studied, including humans, is elevated during digestion, suggesting that a nonadrenergic-noncholinergic factor contributes to the postprandial tachycardia. The regulating factor, however, remains elusive and difficult to identify. Pythons can ingest very large meals, and digestion is associated with a marked rise in metabolism that is sustained for several days. The metabolic rise causes more than a doubling of heart rate and a fourfold rise in cardiac output. This makes the python an interesting model to investigate the postprandial tachycardia. We measured blood pressure and heart rate in fasting Python regius, and at 24 and 48 h after ingestion of a meal amounting to 25% of body wt. Digestion caused heart rate to increase from 25 to 56 min, whereas blood pressure was unchanged. The postprandial rise in heart rate was partially due to a doubling of intrinsic heart rate. The H(2)-antagonist did not affect heart rate of fasting snakes but decreased heart rate by 15-20 min at 24 h into digestion, whereas it had no effects at 48 h. Thus, the histaminergic tone on the heart rose from none to 30% at 24 h but vanished after 48 h. In anesthetized snakes, histamine caused a systemic vasodilatation and a marked increase in heart rate and cardiac output mediated through a direct effect on H(2)- receptors. Our study strongly indicates that histamine regulates heart rate during the initial phase of digestion in pythons. This study describes a novel regulation of the vertebrate heart.

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Section: Vascular Effects Of Histamine In Anesthetized Animalssupporting

confidence: 89%

Section: Data Analysis and Statisticsmentioning

confidence: 99%

Histamine induces postprandial tachycardia through a direct effect on cardiac H₂-receptors in pythons

Skovgaard¹,

Møller²,

Gesser³

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Interestingly, in fish gills, the functional analogue to the lungs of tetrapods, ET-1 leads to a marked vasoconstriction that seems to be caused by contraction of the pillar cells in the gill lamellae (Sundin and Nilsson, 1998;Stensløkken et al, 1999). The lack of effects of ET-1 in the turtle lung is consistent with the very small effects of various regulatory peptides and NO in the pulmonary circulation of most reptiles studied so far (Crossley et al, 2000;Platzack et al, 2002;Galli et al, 2005a,b;Skovgaard et al, 2005).…”

Section: Haemodynamic Effects Of Endothelin In Turtlessupporting

confidence: 78%

Endothelin-1 causes systemic vasodilatation in anaesthetised turtles(Trachemys scripta) through activation of ETB-receptors

Skovgaard

Warren

Jackson

et al. 2005

Journal of Experimental Biology

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“…In contrast to mammals, the role of humoral and local factors in cardiovascular control remains largely unknown in reptiles. Recent studies, nevertheless, indicate that the pulmonary circulation is much less responsive to humoral and local factors than the systemic circulation (8,9,11,16,35,40).Lung structure and heart morphology vary substantially among reptiles. Most snakes and many lizards have unicameral and simple lungs, whereas the multicameral lungs in turtles, varanid lizards, and crocodilians are more complex and compartmentalized (26,31,32,34).…”

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confidence: 99%

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confidence: 99%

Hypoxic pulmonary vasoconstriction in reptiles: a comparative study of four species with different lung structures and pulmonary blood pressures

Skovgaard¹,

Abe²,

Andrade³

et al. 2005

American Journal of Physiology-Regulatory, Integrative and Comp

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Low O2 levels in the lungs of birds and mammals cause constriction of the pulmonary vasculature that elevates resistance to pulmonary blood flow and increases pulmonary blood pressure. This hypoxic pulmonary vasoconstriction (HPV) diverts pulmonary blood flow from poorly ventilated and hypoxic areas of the lung to more well-ventilated parts and is considered important for the local matching of ventilation to blood perfusion. In the present study, the effects of acute hypoxia on pulmonary and systemic blood flows and pressures were measured in four species of anesthetized reptiles with diverse lung structures and heart morphologies: varanid lizards (Varanus exanthematicus), caimans (Caiman latirostris), rattlesnakes (Crotalus durissus), and tegu lizards (Tupinambis merianae). As previously shown in turtles, hypoxia causes a reversible constriction of the pulmonary vasculature in varanids and caimans, decreasing pulmonary vascular conductance by 37 and 31%, respectively. These three species possess complex multicameral lungs, and it is likely that HPV would aid to secure ventilation-perfusion homogeneity. There was no HPV in rattlesnakes, which have structurally simple lungs where local ventilation-perfusion inhomogeneities are less likely to occur. However, tegu lizards, which also have simple unicameral lungs, did exhibit HPV, decreasing pulmonary vascular conductance by 32%, albeit at a lower threshold than varanids and caimans (6.2 kPa oxygen in inspired air vs. 8.2 and 13.9 kPa, respectively). Although these observations suggest that HPV is more pronounced in species with complex lungs and functionally divided hearts, it is also clear that other components are involved.

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Hemodynamic effects of python neuropeptide γ in the anesthetized python, Python regius

Cited by 19 publications

References 28 publications

Histamine induces postprandial tachycardia through a direct effect on cardiac H₂-receptors in pythons

Histamine induces postprandial tachycardia through a direct effect on cardiac H₂-receptors in pythons

Endothelin-1 causes systemic vasodilatation in anaesthetised turtles(Trachemys scripta) through activation of ETB-receptors

Hypoxic pulmonary vasoconstriction in reptiles: a comparative study of four species with different lung structures and pulmonary blood pressures

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Hemodynamic effects of python neuropeptide γ in the anesthetized python, Python regius

Cited by 19 publications

References 28 publications

Histamine induces postprandial tachycardia through a direct effect on cardiac H2-receptors in pythons

Histamine induces postprandial tachycardia through a direct effect on cardiac H2-receptors in pythons

Endothelin-1 causes systemic vasodilatation in anaesthetised turtles(Trachemys scripta) through activation of ETB-receptors

Hypoxic pulmonary vasoconstriction in reptiles: a comparative study of four species with different lung structures and pulmonary blood pressures

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Histamine induces postprandial tachycardia through a direct effect on cardiac H₂-receptors in pythons

Histamine induces postprandial tachycardia through a direct effect on cardiac H₂-receptors in pythons