The autonomic control of upright posture tachycardia in the arboreal lizard Iguana iguana
| Autor: | Luiz Henrique Florindo, Victor Hugo da Silva Braga, Augusto Shinya Abe, Francisco Tadeu Rantin, Vinicius Araújo Armelin, Natalia Miriã Troiano |
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| Rok vydání: | 2018 |
| Předmět: |
030110 physiology
0301 basic medicine Iguana Cardiac output medicine.medical_specialty Physiology Hemodynamics Stroke volume Biology Baroreflex 03 medical and health sciences Autonomic nervous system Blood pressure Internal medicine biology.animal Genetics medicine Cardiology Animal Science and Zoology Molecular Biology Ecology Evolution Behavior and Systematics Venous return curve |
| Zdroj: | Journal of experimental zoology. Part A, Ecological and integrative physiology. |
| ISSN: | 2471-5646 |
| Popis: | In terrestrial environments, upright spatial orientation can dramatically influence animals' hemodynamics. Generally, large and elongated species are particularly sensitive to such influence due to the greater extent of their vascular beds being verticalized, favoring the establishment of blood columns in their bodies along with caudal blood pooling, and thus jeopardizing blood circulation through a cascade effect of reductions in venous return, cardiac filling, stroke volume, cardiac output, and arterial blood pressure. This hypotension triggers an orthostatic-(baroreflex)-tachycardia to normalize arterial pressure, and despite the extensive observation of this heart rate (fH ) adjustment in experiments on orthostasis, little is known about its mediation and importance in ectothermic vertebrates. In addition, most of the knowledge on this subject comes from studies on snakes. Thus, our objective was to expand the knowledge on this issue by investigating it in an arboreal lizard (Iguana iguana). To do so, we analyzed fH , cardiac autonomic tones, and fH variability in horizontalized and tilted iguanas (0°, 30°. and 60°) before and after muscarinic blockade with atropine and double autonomic blockade with atropine and propranolol. The results revealed that I. Iguana exhibits significant orthostatic-tachycardia only at 60o inclinations-a condition that is primarily elicited by a withdrawal of vagal drive. Also, as in humans, increases in low-frequency fH oscillations and decreases in high-frequency fH oscillations were observed along with orthostatic-tachycardia, suggesting that the mediation of this fH adjustment may be evolutionarily conserved in vertebrates. |
| Databáze: | OpenAIRE |
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