The effects of clonidine on arterial baroreflex sensitivity and cardiopulmonary barorefex control of sympathetic nerve activity in patients with left ventricular dysfunction

Author(s):  
Fumio Yuasa ◽  
Akihiro Kawamura ◽  
Hiroshi Yokoe ◽  
Susumu Yoshida ◽  
Kousuke Murakawa ◽  
...  
2019 ◽  
pp. 209-217
Author(s):  
Bing Xiao ◽  
Fan Liu ◽  
Jing-Chao Lu ◽  
Fei Chen ◽  
Wei-Na Pei ◽  
...  

The objective of the paper is to determine the influence of IGF-1 deletion on renal sympathetic nerve activity (RSNA), left ventricular dysfunction, and renal function in deoxycorticosterone acetate (DOCA)-salt hypertensive mice. The DOCA-salt hypertensive mice models were constructed and the experiment was classified into WT (Wild-type mice) +sham, LID (Liverspecific IGF-1 deficient mice) + sham, WT + DOCA, and LID + DOCA groups. Enzyme-linked immunosorbent assay (ELISA) was used to detect the serum IGF-1 levels in mice. The plasma norepinephrine (NE), urine protein, urea nitrogen and creatinine, as well as RSNA were measured. Echocardiography was performed to assess left ventricular dysfunction, and HE staining to observe the pathological changes in renal tissue of mice. DOCA-salt induction time-dependently increased the systolic blood pressure (SBP) of mice, especially in DOCA-salt LID mice. Besides, the serum IGF-1 levels in WT mice were decreased after DOCA-salt induction. In addition, the plasma NE concentration and NE spillover, urinary protein, urea nitrogen, creatinine and RSNA were remarkably elevated with severe left ventricular dysfunction, but the creatinine clearance was reduced in DOCA-salt mice, and these similar changes were obvious in DOCA-salt mice with IGF-1 deletion. Moreover, the DOCA-salt mice had tubular ectasia, glomerular fibrosis, interstitial cell infiltration, and increased arterial wall thickness, and the DOCA-salt LID mice were more serious in those aspects. Deletion of IGF-1 may lead to enhanced RSNA in DOCA-salt hypertensive mice, thereby further aggravating left ventricular dysfunction and renal damage.


1995 ◽  
Vol 268 (1) ◽  
pp. H218-H225 ◽  
Author(s):  
R. Jung ◽  
M. E. Dibner-Dunlap ◽  
M. A. Gilles ◽  
M. D. Thames

Patients with heart failure exhibit a neurohumoral excitatory state and abnormal baroreflex control of the cardiovascular system. We determined whether arterial baroreflexes are impaired during left ventricular dysfunction (LVD) caused by chronic myocardial infarction in the absence of congestive heart failure and whether abnormal central mechanisms contribute to this impairment. Baroreceptors were stimulated in anesthetized rats with and without LVD by increasing arterial pressure with phenylephrine. Lumbar sympathetic nerve and phrenic nerve activity as well as heart rate were recorded. Rats were divided into different groups based on infarct size. Rats with moderate LVD showed impaired baroreflex control of sympathetic, ventilatory, and heart rate responses. Baroreflex gains were inversely related to the size of the infarct. The central gain for sympathetic nerve activity, obtained by using electrical stimulation of the aortic depressor nerve, also was impaired. Baroreflex control of the cardiorespiratory system is thus impaired in rats with moderate LVD in the absence of congestive heart failure. The attenuated baroreflexes are likely due to abnormal afferent mechanisms, although central mechanisms contribute to the impaired barosympathetic reflex.


2000 ◽  
Vol 279 (2) ◽  
pp. H536-H541 ◽  
Author(s):  
Philippe Van de Borne ◽  
Silvia Mezzetti ◽  
Nicola Montano ◽  
Krzysztof Narkiewicz ◽  
Jean Paul Degaute ◽  
...  

Interactions between mechanisms governing ventilation and blood pressure (BP) are not well understood. We studied in 11 resting normal subjects the effects of sustained isocapnic hyperventilation on arterial baroreceptor sensitivity, determined as the α index between oscillations in systolic BP (SBP) generated by respiration and oscillations present in R-R intervals (RR) and in peripheral sympathetic nerve traffic [muscle sympathetic nerve activity (MSNA)]. Tidal volume increased from 478 ± 24 to 1,499 ± 84 ml and raised SBP from 118 ± 2 to 125 ± 3 mmHg, whereas RR decreased from 947 ± 18 to 855 ± 11 ms (all P < 0.0001); MSNA did not change. Hyperventilation reduced arterial baroreflex sensitivity to oscillations in SBP at both cardiac (from 13 ± 1 to 9 ± 1 ms/mmHg, P < 0.001) and MSNA levels (by −37 ± 5%, P < 0.0001). Thus increased BP during hyperventilation does not elicit any reduction in either heart rate or MSNA. Baroreflex modulation of RR and MSNA in response to hyperventilation-induced BP oscillations is attenuated. Blunted baroreflex gain during hyperventilation may be a mechanism that facilitates simultaneous increases in BP, heart rate, and sympathetic activity during dynamic exercise and chemoreceptor activation.


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