The Effects of Feeding on Cardiac Control of the Broad-Nosed Caiman (Caiman latirostris): The Role of the Autonomic Nervous System and NANC Factors

Autor(es)

Da Silva Braga, Victor Hugo ; Armelin, Vinicius Araujo ; Teixeira, Mariana Teodoro ; Abe, Augusto Shinya ; Rantin, Francisco Tadeu ; Florindo, Luiz Henrique

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL GENETICS AND PHYSIOLOGY; v. 325, n. 8, p. 524-531, OCT 2016.
• Citações Web of Science: 7

Resumo

The metabolic increment that occurs after feeding demands cardiovascular adjustments to be maintained, as increased heart rate (f(H)) and cardiac output. In mammals, postprandial tachycardia seems to be triggered by an increase in adrenergic activity and by nonadrenergic noncholinergic (NANC) factors, while in ectothermic vertebrates, this adjustment seems to be linked to a withdrawal of vagal drive as well as to NANC factors. Because the factors behind postprandial tachycardia have not yet been investigated in crocodilians, the present study sought to evaluate the postprandial tachycardia mediators in the broad-nosed caiman. To this end, fasting and digesting animals were instrumented with intraperitoneal cannula and subcutaneous electrocardiogram electrodes (for the measurement of f(H), cardiac autonomic tones, and total f(H) variability, as well as for a power spectral analysis of f(H)). Data were then collected with the animals in an untreated state, as well as after muscarinic cholinergic blockade with atropine (2.5 mg kg(-1)) and after double autonomic blockade with atropine and propranolol (5.0 mg kg-1). Fasting animals' f(H) was similar to 18 bpm, a value which increased to similar to 30 bpm during digestion. After the double autonomic blockade, fasting animals exhibited an f(H) of similar to 15 bpm, while digesting animals' f(H) was similar to 23 bpm. This result is evidence of the presence of NANC factors with positive chronotropic effects acting during digestion. The calculated autonomic tones showed that, after feeding, the adrenergic tone increased while the cholinergic tone remained unchanged. Finally, f(H) variability analyses revealed that this adrenergic increase is primarily derived from circulating catecholamines. (C) 2016 Wiley Periodicals, Inc. (AU)

• Processo FAPESP: 08/57712-4 - Instituto Nacional de Pesquisas em Fisiologia Comparada
• Beneficiário: Augusto Shinya Abe
• Modalidade de apoio: Auxílio à Pesquisa - Temático