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Thermoregulatory adjustments induced by exercise in rats with low brain angiotensinogen
Author(s) -
Leite Laura Hora Rios,
Santiago Henrique Pereira,
Rodrigues Quezia Teixeira,
CampagnoleSantos Maria José,
Coimbra Cândido Celso
Publication year - 2013
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.27.1_supplement.1201.22
Subject(s) - medicine , endocrinology , vasodilation , chemistry , zoology , biology
The effect of exercise on heat balance and performance were assessed in TGR(ASrAogen)‐680 rats (TG) with low glial angiotensinogen production. Sprague‐Dawley (SD) and TG rats (n=7/group) performed an incremental running test to determine their maximal performance. All animals run at 60% of maximal workload until fatigue while body (Tb) and tail (Ttail) temperatures were recorded. Workload (W), the rates of body heating (BHR) and heat storage (HSR) and Tb threshold for tail vasodilation (TTbV) were calculated. The speed that corresponded to 60% of maximal workload was lower in TG rats in comparison with SD animals (19.6 ± 0.5 m.min‐1, SD vs. 15.0 ± 0.3 m.min‐1, TG; p < 0.01). After 13 min of exercise, TG animals showed a greater rise in Tb (13 min: 38.2 ± 0.1 °C, SD vs. 38.5 ± 0.1 °C, TG; p < 0.01) due to the delay in tail skin vasodilation (7.7 ± 0.9 min, SD vs. 11.3 ± 0.7 min, TG; p < 0.01) as well as the higher TTbV (38.0 ± 0.1 °C, SD vs. 38.4 ± 0.1 °C, TG; p < 0.01). The BHR and the HSR of TG animals were, respectively, 39% and 41% higher (p<0.03), both of which closely related with their decreased time to fatigue (p<0.05). The data bring evidence that central angiotensin‐mediated pathways are involved in thermoregulatory heat loss during exercise since low brain angiotensinogen levels attenuate heat dissipation, leading to a faster exercise‐induced increase in Tb associated with decreased performance. Supported by CNPq, FAPEMIG and CAPES