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Altered Activation of RVLM Projecting PVN Neurons to Osmotic and Baroreceptor Challenges in Rats with Chronic Heart Failure
Author(s) -
Xu Bo,
Zheng Hong,
Patel Kaushik K
Publication year - 2011
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.25.1_supplement.845.3
Previous studies indicate that there is increased activation of the paraventricular nucleus (PVN) in rats with chronic heart failure (CHF), as measured by increased hexokinase or cFos activation. However, it is not clear if the pre‐sympathetic neurons within the PVN are specifically overactive, and if they have altered responses to osmotic or baroreflex activation. Experiments were conducted in CHF rats 6–8 weeks after coronary artery ligation with infarcts of 43±3% and LVEDP 22±3mmHg. In 164 spontaneously active neurons recorded in the PVN, 51 units were antidromically activated from the rostral ventrolateral medulla (RVLM). A number of PVN‐RVLM neurons (63%), were excited by internal carotid artery injection of 2.1osmol/L NaCl and 10% were inhibited. Forty‐nine percent of PVN‐RVLM neurons responded to decrease or increase in arterial blood pressure. Baseline discharge rate of PVN‐RVLM neurons in CHF rats was significantly greater than sham rats (7.27±1.31 vs. 2.93±0.76 spikes/s, P <0.05). The responses of PVN‐RVLM neurons discharge rate to hypertonic stimulation was enhanced in rats with CHF compared with sham rats (Δ% 131±17 vs. 91±12, P <0.05). In contrast, the responses of PVN‐RVLM neurons discharge rate to SNP was significantly attenuated (Δ% 52±8 vs. 192±65, P <0.05). Taken together, these data suggest that pre‐sympathetic neurons in the PVN are more active under basal conditions and have an altered response to various cardiovascular challenges. These changes in activation of PVN‐RVM neurons may contribute to the elevated sympatho‐excitation that is observed during CHF. Supported by NIH grant 62222.