Arterial baroreflex dynamics in normotensive and spontaneously hypertensive rats

1992 ◽  
Vol 263 (3) ◽  
pp. R524-R528 ◽  
Author(s):  
S. Harada ◽  
T. Imaizumi ◽  
S. Ando ◽  
Y. Hirooka ◽  
K. Sunagawa ◽  
...  
Keyword(s):  
Transfer Function ◽  
Sympathetic Nerve ◽  
Spontaneously Hypertensive Rats ◽  
Sympathetic Nerve Activity ◽  
Arterial Baroreflex ◽  
Frequency Range ◽  
Hypertensive Rats ◽  
Nerve Activity ◽  
Baroreflex Control ◽  
Spontaneously Hypertensive

To investigate dynamic or frequency-dependent characteristics of arterial baroreflex control of efferent sympathetic nerve activity in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY), we assessed the transfer function from aortic pressure (AP) to renal sympathetic nerve activity (RSNA) using a “white-noise technique.” In pentobarbital sodium-anesthetized rats, we recorded RSNA as the output, while AP was randomly perturbed to impose input pressure changes with broad frequencies. We calculated the transfer function from AP to RSNA over the frequency range of 0.01-5 Hz through the spectral analysis of the input and output. The results indicated that the gain, phase shift, and coherence of the transfer function for SHR and for WKY were similar and statistically indistinguishable. The gain was relatively constant below 0.05 Hz but increased steadily by fivefold as frequency increased in the frequency range of 0.05-0.8 Hz. The phase was out of phase where coherence was high. The coherence was high (greater than 0.5) in the frequency range of 0.04-0.8 and 1.00-1.03 Hz but was low in other frequencies. These results suggest that dynamic or frequency-dependent characteristics of arterial baroreflex control of RSNA were not altered in SHR as compared with WKY.

Arterial baroreflex control of cardiac and renal sympathetic nerve activities is uniform in frequency domain

1991 ◽  
Vol 261 (2) ◽  
pp. R296-R300 ◽  
Author(s):  
S. Harada ◽  
S. Ando ◽  
T. Imaizumi ◽  
Y. Hirooka ◽  
K. Sunagawa ◽  
...  
Keyword(s):  
Phase Shift ◽  
Transfer Function ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Arterial Baroreflex ◽  
Frequency Range ◽  
Nerve Activity ◽  
Baroreflex Control ◽  
Renal Sympathetic Nerve ◽  
Renal Sympathetic

To investigate wideband dynamic properties of arterial baroreflex control of cardiac and renal sympathetic nerve activities, we assessed the transfer function using a "white-noise technique." In pentobarbital sodium-anesthetized cats, we simultaneously recorded, as the output, cardiac sympathetic nerve activity (CSNA) and renal sympathetic nerve activity (RSNA), while aortic pressure (AP) was randomly perturbed to impose input pressure changes with broad frequencies. We calculated the transfer function from AP to CSNA or to RSNA over the frequency range of 0.01-5 Hz through the spectral analysis of the input and output. We found that the gain, phase shift, and coherence of those transfer functions were statistically indistinguishable. The gain was rather flat below 0.05 Hz, steadily increased above 0.05 Hz, and plateaued above 0.3 Hz. The phase shift was out of phase up to 0.05 Hz and led by approximately 4 degrees above 0.05 Hz. The coherence was high (above 0.7) below 0.3 Hz and became lower above 0.3 Hz. These results suggest that arterial baroreflex control is uniform and similar between the two activities in the frequency range of 0.01-0.7 Hz.

scholarly journals Exacerbated pressor and sympathoexcitatory effects of central Elabela in spontaneously hypertensive rats

2020 ◽  
Vol 318 (1) ◽  
pp. H124-H134 ◽  
Author(s):  
Zhi Geng ◽  
Chao Ye ◽  
Ying Tong ◽  
Feng Zhang ◽  
Ye-Bo Zhou ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Sympathetic Nerve ◽  
Spontaneously Hypertensive Rats ◽  
Sympathetic Nerve Activity ◽  
Akt Pathway ◽  
Sympathetic Activation ◽  
Hypertensive Rats ◽  
Nerve Activity ◽  
Vasopressin Release ◽  
Spontaneously Hypertensive

Elabela (ELA) is a newly discovered peptide that acts as a novel endogenous ligand of angiotensin receptor-like 1 (APJ) receptor. This study was designed to evaluate the effects of ELA-21 in paraventricular nucleus (PVN) on blood pressure and sympathetic nerve activity in spontaneously hypertensive rats (SHR). Experiments were performed in male Wistar-Kyoto rats (WKY) and SHR. ELA expression was upregulated in PVN of SHR. PVN microinjection of ELA-21 increased renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), heart rate (HR), plasma norepinephrine, and arginine vasopressin (AVP) levels in SHR. Intravenous injection of ELA-21 significantly decreased MAP and HR in both WKY and SHR, but only induced a slight decrease in RSNA. APJ antagonist F13A in PVN abolished the effects of ELA-21 on RSNA, MAP and HR. Intravenous infusion of both ganglionic blocker hexamethonium and AVP V1a receptor antagonist SR49059 caused significant reduction in the effects of ELA-21 on RSNA, MAP and HR in SHR, while combined administration of hexamethonium and SR49059 abolished the effects of ELA-21. ELA-21 microinjection stimulated Akt and p85α subunit of phosphatidylinositol 3-kinase (PI3K) phosphorylation in PVN, whereas PI3K inhibitor LY294002 or Akt inhibitor MK-2206 almost abolished the effects of ELA-21 on RSNA, MAP, and HR. Chronic PVN infusion of ELA-21 induced sympathetic activation, hypertension, and AVP release accompanied with cardiovascular remodeling in normotensive WKY. In conclusion, ELA-21 in PVN induces exacerbated pressor and sympathoexcitatory effects in hypertensive rats via PI3K-Akt pathway. NEW & NOTEWORTHY We demonstrated that PVN microinjection of ELA-21 increases sympathetic nerve activity and blood pressure, which can be abolished by pretreatment of APJ antagonist. This is the first demonstration that central ELA can induce hypertension. The pressor effects in PVN are mediated by both sympathetic activation and vasopressin release via PI3K-Akt pathway. Our data confirm that ELA is upregulated in the PVN of SHR and so may be involved in the pressor and sympathoexcitatory effects in hypertension.

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