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Contribution of the paraventricular nucleus in the heat stress‐induced cardiovascular adjustments
Author(s) -
Leite Laura H.R.,
Zheng Hong,
Coimbra Candido C,
Patel Kaushik P
Publication year - 2010
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.24.1_supplement.992.3
Subject(s) - vasodilation , microdialysis , medicine , lidocaine , hyperthermia , heart rate , endocrinology , microinjection , mean arterial pressure , anesthesia , blood pressure , chemistry , dopamine
We assessed the effect of hyperthermia on sympathetic nerve activity and blood flow redistribution dictated by the paraventricular nucleus (PVN). Renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), heart rate (HR), body and tail temperatures were recorded in anesthetized rats after bilateral microinjection of CSF, Lidocaine or L‐NMMA into the PVN during heat stress (n=6/group). Heat stress was induced by graded increase in the temperature of a heating pad for 30 min. This stimulus resulted in blunted RSNA response after PVN blockade with Lidocaine (ΔRSNA: 117.6 ± 17.0 % 11.3 ± 7.3 %, CSF vs. Lidocaine, p<0.05), as well as blunted MAP and attenuation of HR increase (ΔMAP: 22 ± 2 mmHg −0.04 ± 7.2 mmHg; ΔHR: 93.4 ± 9.3 bpm 43.4 ± 18.8 bpm, CSF vs. Lidocaine, p<0.05). Change in body temperature for tail vasodilation was unaffected by Lidocaine treatment. RSNA, HR and MAP in L‐NMMA treated rats increased to heating‐stress, similar to CSF treated rats. However, a higher Δbody temperature until tail vasodilation was observed after L‐NMMA (0.3 ± 0.1 °C 0.8 ± 0.1 °C, CSF vs. L‐NMMA, p<0.01). In summary, the PVN participates in increasing renal sympathetic activity to heating, contributing to cardiovascular adjustments that influence core blood redistribution to the periphery. Furthermore, heating possibly increases heat loss through peripheral vasodilation via a nitric oxide mechanism within the PVN.