Single unit recordings from putative presympathetic neurons in the rostral ventrolateral medulla of sedentary and physically active rats (686.35)

Abstract

A sedentary lifestyle has been linked to the development of cardiovascular disease (CVD). The RVLM is believed to contribute to CVD through direct activation of sympathetic preganglionic neurons. Our previous work showed that sedentary rats exhibit enhanced sympathoexcitation after glutamate activation of the RVLM compared to active counterparts. We have also recently shown increased dendritic arborization in spinally‐projecting C1 RVLM neurons from sedentary rats. We hypothesized that the RVLM exhibits increased excitability due to structural and functional differences in sedentary versus active rats (14 weeks wheel running). To our knowledge, we are the first group to have performed in vivo single unit recordings from putative presympathetic RVLM neurons in sedentary and active rats to examine functional differences in presympathetic RVLM neurons. Preliminary results from Inactin‐anesthetized rats indicate that individual presympathetic RVLM neurons from sedentary rats appeared to have higher resting firing rates (14.0±5.1 Hz, n=4) compared to active rats (8.7±3.0 Hz, n=4). RVLM neurons also appeared to have greater responses to acute increases in blood pressure (∆‐11.4±5.3 Hz vs. ∆‐5.6±1.4 Hz, respectively), but decreases in blood pressure did not appear to elicit different responses (∆+3.1±1.4 Hz vs. ∆+2.9±0.3 Hz). Though our current sample size does not yet permit us to draw definitive conclusions, these preliminary data support our hypothesis and suggest that a sedentary lifestyle may increase sympathetic nerve activity by causing an increase in the activity of individual presympathetic RVLM neurons. Grant Funding Source: HL096787, WSU Rumble Fellowship