Postprandial cardiorespiratory responses and the regulation of digestion-associated tachycardia in Nile tilapia (Oreochromis niloticus)

Author(s)

Guagnoni, Igor Noll ^{[1, 2]} ; Armelin, Vinicius Araujo ^{[1, 2, 3]} ; da Silva Braga, Victor Hugo ^{[1, 2]} ; Rantin, Francisco Tadeu ^{[4, 2]} ; Florindo, Luiz Henrique ^{[5, 1, 2]}

Affiliation

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

^[2] FAPESP CNPq, Natl Inst Sci & Technol Comparat Physiol INCT, Sao Paulo - Brazil

^[3] Univ Sao Paulo, Inst Biosci, Dept Physiol, Rua Matao, Travessa 14, 321, BR-05508090 Sao Paulo, SP - Brazil

^[4] Fed Univ Sao Carlos UFSCar, Dept Physiol Sci, Rodovia Washington Luiz, Km 235, BR-13565905 Sao Carlos, SP - Brazil

^[5] Sao Paulo State Univ UNESP, Aquaculture Ctr CAUNESP, Rodovia Prof Paulo Donato Castellane N-N, BR-14884900 Jaboticabal, SP - Brazil

• Document type: Journal article
• Source: JOURNAL OF COMPARATIVE PHYSIOLOGY B-BIOCHEMICAL SYSTEMIC AND ENVIRONMENTAL; v. 191, n. 1, p. 55-67, JAN 2021.
• Web of Science Citations: 0

Abstract

Cardiorespiratory adjustments that occur after feeding are essential to supply the demands of digestion in vertebrates. The well-documented postprandial tachycardia is triggered by an increase in adrenergic activity and by non-adrenergic non-cholinergic (NANC) factors in mammals and crocodilians, while it is linked to a withdrawal of vagal drive and NANC factors in non-crocodilian ectotherms-except for fish, in which the sole investigation available indicated no participation of NANC factors. On the other hand, postprandial ventilatory adjustments vary widely among air-breathing vertebrates, with different species exhibiting hyperventilation, hypoventilation, or even no changes at all. Regarding fish, which live in an environment with low oxygen capacitance that requires great ventilatory effort for oxygen uptake, data on the ventilatory consequences of feeding are also scarce. Thus, the present study sought to investigate the postprandial cardiorespiratory adjustments and the mediation of digestion-associated tachycardia in the unimodal water-breathing teleostOreochromis niloticus. Heart rate (f(H)), cardiac autonomic tones, ventilation rate (f(V)), ventilation amplitude, total ventilation andf(H)/f(V)variability were assessed both in fasting and digesting animals under untreated condition, as well as after muscarinic cholinergic blockade with atropine and double autonomic blockade with atropine and propranolol. The results revealed that digestion was associated with marked tachycardia inO. niloticus, determined by a reduction in cardiac parasympathetic activity and by circulating NANC factors-the first time such positive chronotropes were detected in digesting fish. Unexpectedly, postprandial ventilatory alterations were not observed, although digestion triggered mechanisms that were presumed to increase oxygen uptake, such as cardiorespiratory synchrony. (AU)

• FAPESP's process: 17/01616-6 - Cardiac autonomic control in pre and postprandial situation in the Nile Tilapia, Oreochromis niloticus
• Grantee: Igor Noll Guagnoni
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 08/57712-4 - The National Institute of Comparative Physiological Research
• Grantee: Augusto Shinya Abe
• Support Opportunities: Research Projects - Thematic Grants