Cardiac shunt in the South American rattlesnake, Crotalus durissus: vagal control, hemodynamic patterns and physiological role

• Grant number: 08/00107-1
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: July 01, 2008
• End date: June 30, 2010
• Field of knowledge: Biological Sciences - Physiology - Compared Physiology
• Principal Investigator: Denis Otavio Vieira de Andrade
• Grantee: Cléo Alcantara Costa Leite
• Host Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil

Abstract

The morphology of the reptilian heart results in the mixing of oxygenated and deoxygenated blood. This cardiac shunting normally occurs in chelonians and squamates. The differential distribution of blood flow into the pulmonary and systemic circulations has prompted physiologists to postulate the functional significance of such a circulatory design composing in a picture where the cardiac shunts are not atavistic relics, but represent an important cardiovascular adaptation in extant reptiles. Although experimental evidence attesting the advantageous role of cardiac shunts in pulmonary gas exchange is lacking. In the rattlesnake the pulmonary resistance is the main force driving the magnitude of the R-L shunt. Moreover, on this species the heart receives bilateral vagal innervation while the sphincter on the pulmonary artery is innervated solely by the left vagus. Based on that, it is possible to inhibit the cardiac R-L shunt by left-vagotomy, while not abolishing the parasympathetic vagal influences on the heart and other organs by leaving intact the right branch of the vagus. The possibility of this procedure can make rattlesnake a key species for investigations of the physiological role of cardiac shunt on reptiles. The general aim of this application is to test if the cardiac shunt would provide fundamental adaptive advantage to reptiles. For that we will acquire metabolic and cardiorespiratory parameters in Crotalus durissus for (1) describe the pattern of the cardiac shunt in rattlesnake submitted to diverse physiological challenges like fasting, feeding or activity; (2) compare those parameters between intact snakes and L-vagus sectioned snakes (R-L shunt inhibited) submitted to the mentioned physiological "challenges". (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

TAYLOR, EDWIN W.; LEITE, CLEO A. C.; SARTORI, MARINA R.; WANG, TOBIAS; ABE, AUGUSTO S.; CROSSLEY, II, DANE A.. The phylogeny and ontogeny of autonomic control of the heart and cardiorespiratory interactions in vertebrates. Journal of Experimental Biology, v. 217, n. 5, p. 690-703, MAR 2014. (08/57712-4, 12/16537-0, 12/06938-8, 08/00107-1)