Arterial wall thickening normalizes arterial wall tension with growth in American alligators, Alligator mississippiensis

Autor(es)

Filogonio, Renato ^[1] ; Dubansky, Benjamin D. ^[2] ; Dubansky, Brooke H. ^[3] ; Wang, Tobias ^[4] ; Elsey, Ruth M. ^[5] ; Leite, Cleo A. C. ^[1] ; Crossley, II, Dane A.

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Carlos, Dept Physiol Sci, BR-13565905 Sao Carlos, SP - Brazil

^[2] II, Univ North Texas, Dept Biol Sci, Dev Integrat Biol Cluster, Denton, TX 76203 - USA

^[3] Tarleton State Univ, Dept Med Lab Sci & Publ Hlth, Ft Worth, TX - USA

^[4] Aarhus Univ, Dept Biosci, Sect Zoophysiol, DK-8000 Aarhus C - Denmark

^[5] Louisiana Dept Wildlife & Fisheries, Grand Chenier, LA 70643 - USA

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF COMPARATIVE PHYSIOLOGY B-BIOCHEMICAL SYSTEMIC AND ENVIRONMENTAL; v. 191, n. 3 FEB 2021.
• Citações Web of Science: 0

Resumo

Arterial wall tension increases with luminal radius and arterial pressure. Hence, as body mass (M-b) increases, associated increases in radius induces larger tension. Thus, it could be predicted that high tension would increase the potential for rupture of the arterial wall. Studies on mammals have focused on systemic arteries and have shown that arterial wall thickness increases with M-b and normalizes tension. Reptiles are good models to study scaling because some species exhibit large body size range associated with growth, thus, allowing for ontogenetic comparisons. We used post hatch American alligators, Alligator mississippiensis, ranging from 0.12 to 6.80 kg (similar to 60-fold) to investigate how both the right aortic arch (RAo) and the left pulmonary artery (LPA) change with M-b. We tested two possibilities: (i) wall thickness increases with M-b and normalizes wall tension, such that stress (stress = tension/thickness) remains unchanged; (ii) collagen content scales with M-b and increases arterial strength. We measured heart rate and systolic and mean pressures from both systemic and pulmonary circulations in anesthetized animals. Once stabilized alligators were injected with adrenaline to induce a physiologically relevant increase in pressure. Heart rate decreased and systemic pressures increased with M-b; pulmonary pressures remained unchanged. Both the RAo and LPA were fixed under physiological hydrostatic pressures and displayed larger radius, wall tension and thickness as M-b increased, thus, stress was independent from M-b; relative collagen content was unchanged. We conclude that increased wall thickness normalizes tension and reduces the chances of arterial walls rupturing in large alligators. (AU)

• Processo FAPESP: 16/20158-6 - Adaptações morfofuncionais cardiovasculares para a relação alométrica entre pressão arterial e massa em répteis
• Beneficiário: Renato Filogonio
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 18/05035-0 - Ajustes cardiovasculares em Squamata: validação do modelo da cascavel descerebrada para estudos de mecanismos regulatórios cardiovasculares
• Beneficiário: Cléo Alcantara Costa Leite
• Modalidade de apoio: Auxílio à Pesquisa - Regular