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Exercise training improves heat balance during exercise depending on tail vasodilatation mediated by modification in vascular reactivity
Author(s) -
Guimarães Juliana Bohnen,
Rezende Bruno A.,
Lima Daniel C.,
Rodovalho Gisele V.,
Patel Kaushik P.,
Lemos Virgínia S.,
Coimbra Cândido C.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.955.34
Subject(s) - vasodilation , medicine , hyperthermia , treadmill , cardiology , physical therapy , endocrinology
Exercise induced‐hyperthermia results from imbalance between heat production and heat dissipation. In rats, artery tail dissipates 45% of exercise heat. Therefore, the aim of this study was to assess the influence of exercise training in heat balance during exercise and in tail artery reactivity. Male Wistar rats (weaning) were submitted to 8 weeks of training (Tr, n=6) or kept untrained (Un, n=6). The exercise training was done in a treadmill during 8 weeks in a gradual increase intensity until achieve 25 m/min, 60 min/day with 5% of inclination. After training, body (Tb) and skin tail (Ts) temperatures were evaluated during a session of submaximal exercise (60% VO 2 max). The vascular reactivity in isolated tail artery was evaluated in a bath organ system. The data showed that exercise training increases running performance (30%) and decreases ratio of heat storage/workload in 48%, indicating that training improves heat loss mechanisms. This evidence was reinforced by reduced latency (6.41± 0.71 min, Tr vs 9.75 ± 0.61 min, Un, p<0.01) and by 0.43 o C decrease in Tb threshold to tail vasodilation. Training improved ACh‐induced relaxation in isolated tail artery (P<0,01) that was partially impaired by L‐NAME pretreatment (p<0,05). Our results indicate that exercise training improves heat loss by increasing relaxation of tail artery and decreasing sympathetic tonus to this vessel during exercise.