Key result
Aortic depressor nerve stimulation shows no difference in hemodynamic response timing between hypertensive and normotensive rats.
Why the study?
Does electrical stimulation of the aortic depressor nerve produce different hemodynamic response times in spontaneously hypertensive rats compared to normotensive control rats?
Does electrical stimulation of the aortic depressor nerve produce different hemodynamic response times in spontaneously hypertensive rats compared to normotensive control rats?
p-value: p=>0.05
The study demonstrates that the conduction of electrical impulses in the central and efferent baroreflex pathways is not altered in spontaneously hypertensive rats compared to normotensive controls.
Preserved baroreflex conduction times in this hypertension model; hypothesis-generating for neuromodulation but should not yet inform clinical strategies.
The time to reach the maximum response of arterial pressure, heart rate and vascular resistance (hindquarter and mesenteric) was measured in conscious male spontaneously hypertensive (SHR) and normotensive control rats (NCR; Wistar; 18-22 weeks) subjected to electrical stimulation of the aortic depressor nerve (ADN) under thiopental anesthesia. The parameters of stimulation were 1 mA intensity and 2 ms pulse length applied for 5 s, using frequencies of 10, 30, and 90 Hz. The time to reach the hemodynamic responses at different frequencies of ADN stimulation was similar for SHR (N = 15) and NCR (N = 14); hypotension = NCR (4194 ± 336 to 3695 ± 463 ms) vs SHR (3475 ± 354 to 4494 ± 300 ms); bradycardia = NCR (1618 ± 152 to 1358 ± 185 ms) vs SHR (1911 ± 323 to 1852 ± 431 ms), and the fall in hindquarter vascular resistance = NCR (6054 ± 486 to 6550 ± 847 ms) vs SHR (4849 ± 918 to 4926 ± 646 ms); mesenteric = NCR (5574 ± 790 to 5752 ± 539 ms) vs SHR (5638 ± 648 to 6777 ± 624 ms). In addition, ADN stimulation produced baroreflex responses characterized by a faster cardiac effect followed by a vascular effect, which together contributed to the decrease in arterial pressure. Therefore, the results indicate that there is no alteration in the conduction of the electrical impulse after the site of baroreceptor mechanical transduction in the baroreflex pathway (central and/or efferent) in conscious SHR compared to NCR.
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Durand et al. (2012) studied Hypertension (spontaneously hypertensive rats) (n=29). Electrical stimulation of the aortic depressor nerve vs. Normotensive control rats was evaluated on Time to reach the maximum response of arterial pressure, heart rate, and vascular resistance (p=>0.05). Electrical stimulation of the aortic depressor nerve demonstrated no significant differences in the time elapsed to reach maximum mean arterial pressure, heart rate, and vascular resistance responses between conscious spontaneously hypertensive and normotensive control rats.
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