scholarly journals Hemodynamic defense response to thyrotropin-releasing hormone injected into medial preoptic nucleus in rats

1991 ◽  
Vol 261 (2) ◽  
pp. R305-R312 ◽  
Author(s):  
A. L. Siren ◽  
S. Vonhof ◽  
G. Feuerstein
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Defense Response ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Renal Sympathetic

The role of thyrotropin-releasing hormone (TRH) and glutamate in central cardiovascular control was studied by microinjections (50 nl) of these agents into the medial or median preoptic nuclei of conscious rats (n = 49) with continuous recording of mean arterial pressure, heart rate, blood flow, and vascular resistance in hindquarter, renal, and mesenteric blood vessels. In addition, the effect of TRH on renal sympathetic nerve activity was studied in anesthetized rats. TRH (2.4-240 pmol) elicited the typical hemodynamic pattern of the "defense response" consisting of increased blood pressure, tachycardia, hindquarter vasodilation, and constriction of renal and mesenteric blood vessels. Maximum changes in cardiovascular variables after the 24-pmol dose were +12 +/- 2 mmHg (mean arterial pressure), +73 +/- 15 beats/min (heart rate), -21 +/- 6% (hindquarter resistance), +15 +/- 6% (renal resistance), and +31 +/- 6% (mesenteric resistance), P less than 0.05 compared with saline. In anesthetized rats, TRH at the 2.4-pmol dose increased renal sympathetic nerve activity (greater than 200%, n = 5, P less than 0.05 compared with control) with no effect on blood pressure or renal flow. Glutamate (10 or 100 nmol) produced a similar pattern of hemodynamic changes as TRH. Peak effects after the 100-nmol dose of glutamate were +16 +/- 2 mmHg (mean arterial pressure), +57 +/- 11 beats/min (heart rate), -31 +/- 3% (hindquarter resistance), +29 +/- 9% (renal resistance), and +87 +/- 22% (mesenteric resistance), P less than 0.05 compared with saline. The glutamate N-methyl-D-aspartate (NMDA) receptor blocker MK-801 (300 micrograms/kg iv) attenuated the pressor-tachycardic responses to TRH and the pressor-mesenteric constrictor responses to glutamate.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular and neurohormonal effects of intravenous adrenomedullin in conscious rabbits

1995 ◽  
Vol 269 (5) ◽  
pp. R1289-R1293 ◽  
Author(s):  
M. Fukuhara ◽  
T. Tsuchihashi ◽  
I. Abe ◽  
M. Fujishima
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Renal Sympathetic Nerve ◽  
Conscious Rabbits ◽  
Renal Sympathetic

Adrenomedullin is a vasodilative peptide and shows slight homology with calcitonin gene-related peptide. In the present study, we investigated the effects of adrenomedullin on cardiovascular and neurohormonal responses in 13 conscious rabbits. The animals were chronically instrumented with bipolar electrodes on the left renal sympathetic nerve. Intravenous administration of human adrenomedullin (10, 100, 1,000, and 3,000 pmol/kg, n = 6) caused a dose-dependent reduction in mean arterial pressure (0 +/- 2, -1 +/- 2, -19 +/- 2, and -29 +/- 4 mmHg, respectively) concomitant with increases in heart rate, renal sympathetic nerve activity, plasma renin activity, and plasma norepinephrine. The significant reduction in mean arterial pressure induced by 1,000 pmol/kg of adrenomedullin occurred within 1 min after injection and lasted for 15 min (n = 7). In contrast, the significant increases in heart rate and renal sympathetic nerve activity lasted for more than 50 min. When mean arterial pressure was decreased by 15 mmHg by adrenomedullin, the increases in heart rate and renal sympathetic nerve activity were 53 +/- 8 beats/min and 78 +/- 13%, respectively, which were significantly smaller than those induced by intravenous injection of sodium nitroprusside (102 +/- 14 beats/min and 155 +/- 34%, respectively). These results suggest that intravenous adrenomedullin exerts a hypotensive action that is associated with the attenuated reflex-mediated sympathetic activation.

scholarly journals Cardiopulmonary baroreflex function in nephrotic rats.

1995 ◽  
Vol 5 (12) ◽  
pp. 2082-2086
Author(s):  
J C Neahring ◽  
S Y Jones ◽  
G F DiBona
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Renal Sympathetic Nerve ◽  
Cardiopulmonary Baroreflex ◽  
Renal Sympathetic

Efferent renal sympathetic nerve activity is increased in experimental nephrotic syndrome and exhibits attenuated cardiopulmonary baroreflex inhibition during volume expansion in anesthetized rats. Additional studies were performed in conscious rats to avoid the potentially confounding influences of anesthesia; these studies used another more specific standardized stimulus for cardiopulmonary baroreflex activation. Sprague Dawley rats were studied 3 to 4 wk after adriamycin injection (3.5 mg/kg iv); all rats developed proteinuria. In sinoaortic denervated rats (anesthetized), graded frequency stimulation of the central end of the cut right vagus nerve produced frequency-dependent decreases in mean arterial pressure, heart rate, and efferent renal sympathetic nerve activity. The decreases in mean arterial pressure and heart rate were similar in control and nephrotic rats, but efferent renal sympathetic nerve activity decreased significantly less in nephrotic than control rats over the entire frequency range (P < 0.02). In sinoaortic denervated rats (conscious), 10% body weight isotonic saline volume expansion decreased mean arterial pressure, heart rate, and efferent renal sympathetic nerve activity. The decreases in mean arterial pressure and heart rate were similar in control and nephrotic rats, but efferent renal sympathetic nerve activity decreased significantly less in nephrotic than control rats over the entire period of volume expansion (P < 0.04). In nephrotic syndrome, the cardiopulmonary baroreflex inhibition of efferent renal sympathetic nerve activity is decreased; the defect lies in the central portion of the reflex. This may contribute to the observed increase in efferent renal sympathetic nerve activity in nephrotic syndrome.

Hypertonic sodium resuscitation after hemorrhage improves hemodynamic function by stimulating cardiac, but not renal, sympathetic nerve activity

2011 ◽  
Vol 300 (2) ◽  
pp. H685-H692 ◽  
Author(s):  
Robert Frithiof ◽  
Rohit Ramchandra ◽  
Sally G. Hood ◽  
Clive N. May
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Hypertonic Saline ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Renal Sympathetic

Small volume hypertonic saline resuscitation can be beneficial for treating hemorrhagic shock, but the mechanism remains poorly defined. We investigated the effects of hemorrhagic resuscitation with hypertonic saline on cardiac (CSNA) and renal sympathetic nerve activity (RSNA) and the resulting cardiovascular consequences. Studies were performed on conscious sheep instrumented with cardiac ( n = 7) and renal ( n = 6) sympathetic nerve recording electrodes and a pulmonary artery flow probe. Hemorrhage (20 ml/kg over 20 min) caused hypotension and tachycardia followed by bradycardia, reduced cardiac output, and abolition of CSNA and RSNA. Resuscitation with intravenous hypertonic saline (1.2 mol/l at 2 ml/kg) caused rapid, dramatic increases in mean arterial pressure, heart rate, and CSNA, but had no effect on RSNA. In contrast, isotonic saline resuscitation (12 ml/kg) had a much delayed and smaller effect on CSNA, less effect on mean arterial pressure, no effect on heart rate, but stimulated RSNA, although the plasma volume expansion was similar. Intracarotid infusion of hypertonic saline (1 ml/min bilaterally, n = 5) caused similar changes to intravenous administration, indicating a cerebral component to the effects of hypertonic saline. In further experiments, contractility (maximum change in pressure over time), heart rate, and cardiac output increased significantly more with intravenous hypertonic saline (2 ml/kg) than with Gelofusine (6 ml/kg) after hemorrhage; the effects of hypertonic saline were attenuated by the β-receptor antagonist propranolol ( n = 6). These results demonstrate a novel neural mechanism for the effects of hypertonic saline resuscitation, comprising cerebral stimulation of CSNA by sodium chloride to improve cardiac output by increasing cardiac contractility and rate and inhibition of RSNA.

Hemodynamic and sympathetic effects of spinal administration of neuropeptide Y in rats

1990 ◽  
Vol 259 (6) ◽  
pp. H1674-H1680 ◽  
Author(s):  
X. L. Chen ◽  
M. M. Knuepfer ◽  
T. C. Westfall
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Peripheral Resistance ◽  
Intrathecal Administration ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Renal Sympathetic Nerve ◽  
Renal Sympathetic

Intrathecal administration of 4 nmol/kg neuropeptide Y in Dial-urethane-anesthetized rats elicited decreases in arterial pressure, renal sympathetic nerve activity, and a slight decrease in heart rate. The depressor response was associated with a sustained hindquarters and mesenteric vasodilation resulting in a decrease in total peripheral resistance. Intrathecal NPY also resulted in a decrease in renal sympathetic nerve activity. There was a positive correlation between the percent changes in arterial pressure and renal sympathetic nerve activity. With the use of renal nerve activity and heart rate as indexes, NPY resulted in a decrease in baroreflex sensitivity. The depressor effect of intrathecal NPY did not appear to be due to spinal vasoconstriction and ischemia, since spinal microvascular resistance was decreased slightly. We conclude that the intrathecal administration of NPY produces an inhibition of sympathetic nerve activity, resulting in a decrease in total peripheral resistance and arterial pressure.

IL (Interleukin)-17A Acts in the Brain to Drive Neuroinflammation, Sympathetic Activation, and Hypertension

Hypertension ◽  
2021 ◽  
Vol 78 (5) ◽  
pp. 1450-1462
Author(s):  
Yiling Cao ◽  
Yang Yu ◽  
Baojian Xue ◽  
Ye Wang ◽  
Xiaolei Chen ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Intravenous Injection ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Renal Sympathetic Nerve ◽  
The Brain ◽  
Renal Sympathetic

IL (Interleukin)-17A is a key inflammatory mediator contributing to chronic tissue inflammation. The present study sought to determine whether IL-17A plays a role in regulating neuroinflammation, hemodynamics, and sympathetic outflow in normal and hypertensive animals. In urethane-anesthetized rats, intravenous injection of IL-17A induced dramatic and prolonged increases in blood pressure, heart rate, and renal sympathetic nerve activity, which were significantly attenuated by an IL-17RA (IL-17 receptor A) siRNA in the hypothalamic paraventricular nucleus (PVN). Either intracerebroventricular or PVN microinjection of IL-17A also elicited a similar excitatory response in blood pressure, heart rate, and renal sympathetic nerve activity. Intravenous injection of IL-17A upregulated the mRNA level of IL-17A, IL-17F, and IL-17RA in the PVN. Additionally, intravenous injection of IL-17A activated brain-resident glial cells and elevated the gene expression of inflammatory cytokines and chemokines in the PVN, which were markedly diminished by PVN microinjection of IL-17RA siRNA. Pretreatments with microglia or astrocyte inhibitors attenuated the increase in blood pressure, heart rate, and renal sympathetic nerve activity in response to PVN IL-17A. Moreover, intracerebroventricular injection of IL-17A activated TGF (transforming growth factor)-β activated kinase 1, p44/42 mitogen-activated protein kinase, and transcriptional nuclear factor κB in the PVN. IL-17A interacted with tumor necrosis factor-α or IL-1β synergistically to exaggerate its influence on hemodynamic and sympathetic responses. Central intervention suppressing IL-17RA in the PVN significantly reduced angiotensin II–induced hypertension, neuroinflammation, and sympathetic tone in the rats. Collectively, these data indicated that IL-17A in the brain promotes neuroinflammation to advance sympathetic activation and hypertension, probably by a synergistic mechanism involving the interaction with various inflammatory mediators within the brain.

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