Autonomic control of cardiovascular adjustments associated with orthostasis in the scansorial snake Boa constrictor

Author(s)

Armelin, Vinicius Araujo ^{[1, 2]} ; da Silva Braga, Victor Hugo ^{[1, 2]} ; Guagnoni, Igor Noll ^{[1, 2]} ; Crestani, Ariela Maltarolo ^{[1, 2]} ; Abe, Augusto Shinya ^{[2, 3, 4]} ; Florindo, Luiz Henrique ^{[1, 2, 3]}

Affiliation

^[1] Sao Paulo State Univ UNESP, Dept Zool & Bot, Rua Cristovao Colombo 2265, BR-15054000 Sao Jose Do Rio Preto, SP - Brazil

^[2] Natl Inst Sci & Technol Comparat Physiol INCT FIS, BR-13506900 Rio Claro, SP - Brazil

^[3] Sao Paulo State Univ UNESP, Aquaculture Ctr CAUNESP, Rodovia Prof Paulo Donato Castellane N-N, BR-14884900 Jaboticabal, SP - Brazil

^[4] Sao Paulo State Univ UNESP, Dept Zool, Ave 24A, 1515, BR-13506900 Rio Claro, SP - Brazil

• Document type: Journal article
• Source: Journal of Experimental Biology; v. 222, n. 5 MAR 2019.
• Web of Science Citations: 0

Abstract

Orthostatic hypotension is a phenomenon triggered by a change in the position or posture of an animal, from a horizontal to a vertical head-up orientation, characterised by a blood pooling in the lower body and a reduction in central and cranial arterial blood pressure (P-A). This hypotension elicits systemic vasoconstriction and tachycardia, which generally reduce blood pooling and increase P-A. Little is known about the mediation and importance of such cardiovascular adjustments that counteract the haemodynamic effects of orthostasis in ectothermic vertebrates, and some discrepancies exist in the information available on this subject. Thus, we sought to expand our knowledge on this issue by investigating it in a more elaborate way, through an in vivo pharmacological approach considering temporal circulatory changes during head-up body inclinations in unanaesthetised Boa constrictor. To do so, we analysed temporal changes in P-A, heart rate (f(H)) and cardiac autonomic tone associated with 30 and 60 deg inclinations, before and after muscarinic blockade with atropine, double blockade with atropine and propranolol, and alpha(1)-adrenergic receptor blockade with prazosin. Additionally, the animals' f(H) variability was analysed. The results revealed that, in B. constrictor: (1) the orthostatic tachycardia is initially mediated by a decrease in cholinergic tone followed by an increase in adrenergic tone, a pattern that may be evolutionarily conserved in vertebrates; (2) the orthostatic tachycardia is important for avoiding an intense decrease in P-A at the beginning of body inclinations; and (3) alpha(1)-adrenergic orthostatic vasomotor responses are important for the maintenance of P-A at satisfactory values during long-term inclinations. (AU)

• FAPESP's process: 08/57712-4 - The National Institute of Comparative Physiological Research
• Grantee: Augusto Shinya Abe
• Support Opportunities: Research Projects - Thematic Grants