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Figure 3 Systolic blood pressure (SBP), heart rate (HR), and muscle sympathetic nerve activity (MSNA) responses after snuff tobacco (n = 10) as compared to phenylephrine infusion (in the absence of chewing tobacco) (n = 8). Heart rate increased during tobacco, but decreased with phenylephrine. Despite increased blood pressure during tobacco, there was no significant decrease in MSNA, although MSNA was virtually eliminated during phenylephrine. Faster HR and minimal MSNA suppression, despite the similar blood pressures with spit tobacco use compared to phenylephrine, suggest a potent cardiac and vascular excitatory effect of spit tobacco, which overcomes the cardiac and sympathetic inhibitory influences of baroreflex activation in response to the rise in blood pressure.
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