Neural Regulation of Arterial Blood Pressure in Snakes

Lillywhite, Harvey B.; Donald, John A.

doi:10.1086/physzool.67.6.30163897

Cited by 51 publications

(60 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This implies that the effective site of baroreception lies near the heart rather than further up the neck. It is also consistent with morphological and physiological evidence of baroreceptors in the truncus arteriosus and central arteries of snakes (Lillywhite and Donald, 1994).…”

Section: Discussionsupporting

confidence: 86%

“…In this case, there is no blood pooling, yet blood flow to the head apparently ceases, because unprotected arteries and microvessels close under negative blood pressure. Blood flow in the carotid artery of snakes has been shown to cease when the central arterial blood pressure equals or falls below the equivalent of the hydrostatic blood column above the heart (Lillywhite, 1993;Lillywhite and Donald, 1994). On its own, blood pooling in file snakes has little influence on head arterial pressure, but when combined in a full tilt exacerbates the problem by causing head arterial pressure to become negative at lower tilt angles (Fig.·5).…”

Section: Discussionmentioning

confidence: 99%

“…Arterial blood pressure increases in relation to head-heart distance in terrestrial species, and the heart moves relatively closer to the head from aquatic through terrestrial and arboreal species (Seymour, 1987). Terrestrial and arboreal species show more effective baroreflexes in response to tilting (Lillywhite and Donald, 1994;Lillywhite and Pough, 1983;Lillywhite and Seymour, 1978;Seymour and Lillywhite, 1976;Young et al, 1997), and they have more effective mechanisms to prevent blood pooling and oedema in the dependent end, including less compliant vessels or tissues, narrower bodies Changes in orientation in a gravitational field markedly alter the patterns of blood pressure and flow in animals, especially tall or long ones such as giraffes or snakes. Vertical orientation tends to reduce blood flow and pressure in the head for two major reasons.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Independent effects of heart–head distance and caudal blood pooling on blood pressure regulation in aquatic and terrestrial snakes

Seymour

Arndt

2004

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARY Changes in orientation in a gravitational field markedly alter the patterns of blood pressure and flow in animals, especially tall or long ones such as giraffes or snakes. Vertical orientation tends to reduce blood flow and pressure in the head for two major reasons. First, the increased vertical blood column above the heart creates a gravitational hydrostatic pressure against which the heart must work. Second, expansion of dependent vessels in the lower extremities causes blood pooling and reduces return of venous blood to the heart, thereby lowering flow and pressure. For most animals, it is difficult to separate these two effects, but snakes offer the possibility of bending the animal in the region of the heart and manipulating the two ends of the body independently. We studied baroregulatory responses in terrestrial pythons (Liasis fuscus) and aquatic file snakes (Acrochordus arafurae) by tilting only the front or rear parts and then the whole animal. Changes in head blood pressure during partial tilts added up to the change during full tilt. The vertical distance to the head had twice as much influence on head blood pressure than did blood pooling in the pythons and four times as much in file snakes. This accounts for the cephalad location of the heart in terrestrial species compared with aquatic ones.

show abstract

Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Independent effects of heart–head distance and caudal blood pooling on blood pressure regulation in aquatic and terrestrial snakes

Seymour

Arndt

2004

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…Hagensen et al (2010) used a similar pharmacological protocol to that in the present study in broad nosed caiman (Caiman latirostris) and noted that the tachycardia following SNP was greater when caiman were acutely warmed from 15 to 30°C. Similar patterns were observed in tilt experiments on restrained tiger snakes (Notechis scutatus) at different acutely altered temperatures (Lillywhite and Seymour, 1978), and after short-term (<2.5 weeks) acclimation to 13 and 3°C in red-eared sliders (Trachemys scripta) . Nonetheless, to our knowledge, this study shows for the first time in fish that the cardiac limb of the baroreflex is strongly affected by chronic (i.e.…”

Section: Discussion Temperature Effects On Barostatic Reflexes In Fissupporting

confidence: 74%

Cardiac reflexes in a warming world: Thermal plasticity of barostatic control and autonomic tones in a temperate fish

Sandblom

Ekström

Brijs

et al. 2016

Journal of Experimental Biology

View full text Add to dashboard Cite

Thermal plasticity of cardiorespiratory function allows ectotherms like fish to cope with seasonal temperature changes and is critical for resilience to climate change. Yet, the chronic thermal effects on cardiovascular homeostatic reflexes in fish are little understood although this may have important implications for physiological performance and overall resilience to climate warming. We compared cardiac autonomic control and baroreflex regulation of heart rate in perch (Perca fluviatilis L.) from a reference area in the Baltic Sea at 18-19°C with conspecifics from the Biotest enclosure, a chronically heated ecosystem receiving warmed effluent water (24-25°C) from a nuclear power plant. Resting heart rate of Biotest fish displayed clear thermal compensation and was 58.3±2.3 beats min −1 compared with 52.4±2.6 beats min −1 in reference fish at their respective environmental temperatures (Q 10 =1.2). The thermally compensated heart rate of Biotest fish was a combined effect of elevated inhibitory cholinergic tone (105% in Biotest fish versus 70% in reference fish) and reduced intrinsic cardiac pacemaker rate. A barostatic response was evident in both groups, as pharmacologically induced increases and decreases in blood pressure resulted in atropine-sensitive bradycardia and tachycardia, respectively. Yet, the tachycardia in Biotest fish was significantly greater, presumably due to the larger scope for vagal release. Acclimation of Biotest fish to 18°C for 3 weeks abolished differences in intrinsic heart rate and autonomic tone, suggesting considerable short-term thermal plasticity of cardiovascular control in this species. The heightened hypotensive tachycardia in Biotest perch may represent an important mechanism of ectothermic vertebrates that safeguards tissue perfusion pressure when tissue oxygen demand is elevated by environmental warming.

show abstract

“…IB). This cholinergic effect is common to all reptiles, although vasoactive intestinal peptide (VIP) and other neuropeptides are important as vagal neurotransmitters in some species of snakes (reviewed by Lillywhite & Donald, 1994;Morris & Nilsson, 1994). In Crutulus, there is also a large adrenergic tone on the heart that is disclosed after injection of propranolol (Fig.…”

Section: Vagal Control Of Tidal Volume and Breathing Patternmentioning

confidence: 99%