Enhanced Sympathetic Activity Caused by Salt Loading in Spontaneously Hypertensive Rats

1980 ◽  
Vol 59 (s6) ◽  
pp. 171s-173s ◽  
Author(s):  
R. Dietz ◽  
A. Schoumig ◽  
W. Rascher ◽  
R. Strasser ◽  
W. Kubler
Keyword(s):  
Sympathetic Activity ◽  
Spontaneously Hypertensive Rats ◽  
Hypertensive Rats ◽  
Salt Loading ◽  
Plasma Adrenaline ◽  
Spontaneously Hypertensive ◽  
Noradrenaline Concentration ◽  
Wistar Kyoto ◽  
Distinct Increase ◽  
Stimulation Of

1. Salt loading accelerates and increases the rise in blood pressure (spSH) in stroke-prone spontaneously hypertensive rats, but not in Wistar-Kyoto (WK) rats. 2. In both strains a slight increase in plasma volume was obtained during salt loading. 3. Salt loading caused a distinct increase in plasma noradrenaline concentration in spSH rats, but a slight decrease in WK rats. Plasma adrenaline and dopamine concentrations remained unaffected. 4. Exposure to cold resulted in a more marked stimulation of sympathoadrenal and sympathoneuronal activity in salt-loaded spSH rats than in spSH rats on a normal sodium diet. 5. It is concluded that salt loading results in a further increase of the already elevated sympathetic activity in spSH rats.

Diminished sympathetic silent period in spontaneously hypertensive rats

1979 ◽  
Vol 236 (3) ◽  
pp. R147-R152 ◽  
Author(s):  
L. P. Schramm ◽  
G. N. Barton
Keyword(s):  
Electrical Stimulation ◽  
Sympathetic Activity ◽  
Spontaneously Hypertensive Rats ◽  
Silent Period ◽  
Spontaneous Hypertension ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Splanchnic Nerves ◽  
Wistar Kyoto ◽  
Stimulation Of

To determine if elevated sympathetic activity occurs in spontaneously hypertension, the silent period induced in splanchnic nerves following electrical stimulation of dorsal medullary sympathoexcitatory sites was compared in anesthetized normotensive Wistar Kyoto rats (WKYs) and Okamoto spontaneously hypertensive rats (SHRs). The strength of silent periods was defined as the degree of inhibition of responses to testing stimuli delivered at various latencies following conditioning trains, and it was assumed to be inversely related to the level of sympathetic activity. Weanling SHRs exhibited weaker silent periods than weanling WKYs although, at that age, the arterial pressures of the strains were not significantly different. Silent periods were also weaker in adult SHRs than in adult WKYs. This difference persisted after arterial pressures, which fell under anesthesia, were raised by phenylephrine infusions to the respective "normal" levels in each strain. These results support the hypothesis that elevated sympathetic activity exists during both the development and maintenance of spontaneous hypertension in rats.

Further analysis of cell membrane changes in genetic hypertension in rats by diphenylhexatriene fluorescence polarization

1984 ◽  
Vol 66 (6) ◽  
pp. 717-723 ◽  
Author(s):  
I. Aracon-Birlouez ◽  
T. Montenay-Carestier ◽  
M. A. Devynck
Keyword(s):  
Spontaneously Hypertensive Rats ◽  
Erythrocyte Membranes ◽  
Shr Rats ◽  
Erythrocyte Ghosts ◽  
Hypertensive Rats ◽  
Salt Loading ◽  
Spontaneously Hypertensive ◽  
Platelet Membranes ◽  
Wistar Kyoto ◽  
Membrane Changes

1. Fluorescence Dolarization of dbhenvlhexa-triene embedded in membranes was used as an index of ‘microviscosity’ in platelets and ervthro—cyte ghosts of spontaneously hypertensive rats of the Okamoto-Aoki strain (SHR), Wistar-Kyoto strain (WKY) and of the hypertension-prone and -resistant Sabra strains (SBH and SBN), and the original Sabra strain (SB). 2. Microviscosity was increased both in erythrocyte ghosts and platelet membranes of male but not female SHR rats compared with WKY rats and in hypertension-prone Sabra rats compared with the original Sabra rats. 3. Acute and chronic salt loading increased the microviscosity of platelet membranes in all strains of rats but had no effect on the erythrocyte membranes. 4. Microviscosities of vesicles made of lipids extracted from SHR and WKY erythrocyte ghosts were similar. This supports the hypothesis that membrane proteins play a major role in the differences in microviscosity observed in SHR rats.

Effects of dietary sodium on central and peripheral ouabain-like activity in spontaneously hypertensive rats

1993 ◽  
Vol 264 (6) ◽  
pp. H2051-H2055 ◽  
Author(s):  
F. H. Leenen ◽  
E. Harmsen ◽  
H. Yu ◽  
C. Ou
Keyword(s):  
Left Ventricle ◽  
Sympathetic Activity ◽  
Spontaneously Hypertensive Rats ◽  
Dietary Sodium ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Wky Rats ◽  
Wistar Kyoto ◽  
Later Phase ◽  
Shr And Wky Rats

High dietary Na+ intake enhances pressor and sympathoexcitatory responses in spontaneously hypertensive rats (SHR) but not Wistar-Kyoto (WKY) rats. To evaluate the possible contribution of central ouabain-like activity (OLA), brain and peripheral OLA was assessed in SHR vs. WKY rats at 4 wk of age and after 2 and 4 wk of high vs. control Na+ intake started at 4 wk of age. In SHR, hypertension developed with maturation and was exacerbated by high Na+ intake. With control Na+ intake, SHR showed higher OLA at 4, 6, and 8 wk of age in the pituitary and hypothalamus and also by 8 wk in the adrenals and left ventricle but not in plasma. High Na+ intake increased OLA in all tissues examined in both WKY rats and SHR. After 2 wk on high Na+, only OLA in hypothalamus and pituitary was higher in SHR vs. WKY rats; after 4 wk on high Na+, peripheral (i.e., adrenals, left ventricle, and plasma) OLA was also higher. These results indicate that in SHR the development of hypertension is associated early on with increases in central OLA and in a later phase with increases in peripheral OLA as well. High Na+ intake increases OLA in both SHR and WKY rats, but the higher OLA may affect sympathetic activity and blood pressure only in SHR.

Sympathetic activity in spontaneously hypertensive rats after spinal transection

1982 ◽  
Vol 243 (5) ◽  
pp. R506-R511 ◽  
Author(s):  
L. P. Schramm ◽  
E. S. Chornoboy
Keyword(s):  
Sympathetic Activity ◽  
Spontaneously Hypertensive Rats ◽  
Hypertensive Rats ◽  
Nerve Activity ◽  
Renal Nerve ◽  
Spontaneously Hypertensive ◽  
Sympathetic Hyperactivity ◽  
Ganglionic Blockade ◽  
Renal Nerve Activity ◽  
Wistar Kyoto

To test the hypothesis that sympathetic hyperactivity and hyperexcitability in spontaneously hypertensive rats (SHR) is generated at spinal and/or ganglionic levels, we measured integrated renal nerve activity (before ganglionic blockade) and adrenal nerve activity (after ganglionic blockade) in 12- to 14-wk-old SHR and normotensive Wistar-Kyoto rats (WKY). Rats were anesthetized with alpha-chloralose, artificially respired, and paralyzed. Spinal cords were transected at C1 to eliminate normal supraspinal control of sympathetic activity. The effectiveness of descending sympathoexcitatory and sympathoinhibitory pathways was tested by measuring changes in nerve activity elicited by graded spinal stimulation. Spontaneous renal nerve activity was elevated in SHR, but stimulation of descending excitatory pathways caused similar responses in SHR and WKY. Spontaneous adrenal preganglionic nerve activity was similar in SHR and WKY, but excitatory stimulation elicited larger adrenal nerve responses in SHR. We conclude that spinal and/or ganglionic mechanisms may generate a component of the sympathetic hyperactivity exhibited by SHR. The larger adrenal preganglionic nerve responses to excitatory stimulation in SHR suggest that spinal systems may be partially responsible for adrenomedullary hyperexcitability in spontaneous hypertension.

Erectile dysfunction in spontaneously hypertensive rats: pathophysiological mechanisms

2003 ◽  
Vol 284 (3) ◽  
pp. R682-R688 ◽  
Author(s):  
Delphine Behr-Roussel ◽  
Philippe Chamiot-Clerc ◽  
Jacques Bernabe ◽  
Katell Mevel ◽  
Laurent Alexandre ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Electrical Stimulation ◽  
Erectile Dysfunction ◽  
Spontaneously Hypertensive Rats ◽  
Isometric Tension ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto ◽  
Stimulation Of

Hypertensive men have a higher prevalence of erectile dysfunction (ED) than the general population. Experimental evidence of ED in hypertensive animals is scarce. This study evaluates the erectile function of spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto rats (WKY) in vivo by the increase in intracavernosal pressure after electrical stimulation of the cavernous nerve (CN) and by isometric tension studies on corporal strips. Frequency-dependent erectile responses to CN stimulations were reduced in SHR. Phenylephrine induced lower corporal contractions in SHR although pD2 values were similar to WKY. Endothelium-dependent relaxations to ACh were impaired significantly in SHR, and indomethacin improved these relaxations in both WKY and SHR, the latter thus reaching values similar to WKY. Corporal relaxations to sodium nitroprusside were enhanced in SHR. Thus a dysfunctional α-adrenergic contraction of the corporal smooth muscle, an increased cyclooxygenase-dependent constrictor tone, and/or a defect in endothelium-dependent reactivity are associated with the altered erectile mechanisms in SHR. Drugs targeting endothelial dysfunction may delay the occurrence of ED as a complication of hypertension.

Excess oxygen delivery during muscle contractions in spontaneously hypertensive rats

1995 ◽  
Vol 78 (1) ◽  
pp. 101-111 ◽  
Author(s):  
J. M. Lash ◽  
H. G. Bohlen
Keyword(s):  
Blood Flow ◽  
Oxygen Saturation ◽  
Oxygen Delivery ◽  
Spontaneously Hypertensive Rats ◽  
Muscle Contractions ◽  
Hypertensive Rats ◽  
Hemoglobin Oxygen Saturation ◽  
Spontaneously Hypertensive ◽  
Tissue Po2 ◽  
Wistar Kyoto

These experiments determined whether a deficit in oxygen supply relative to demand could account for the sustained decrease in tissue PO2 observed during contractions of the spinotrapezius muscle in spontaneously hypertensive rats (SHR). Relative changes in blood flow were determined from measurements of vessel diameter and red blood cell velocity. Venular hemoglobin oxygen saturation measurements were performed by using in vivo spectrophotometric techniques. The relative dilation [times control (xCT)] of arteriolar vessels during contractions was as large or greater in SHR than in normotensive rats (Wistar-Kyoto), as were the increases in blood flow (2 Hz, 3.50 +/- 0.69 vs. 3.00 +/- 1.05 xCT; 4 Hz, 10.20 +/- 3.06 vs. 9.00 +/- 1.48 xCT; 8 Hz, 16.40 +/- 3.95 vs. 10.70 +/- 2.48 xCT). Venular hemoglobin oxygen saturation was lower in the resting muscle of SHR than of Wistar-Kyoto rats (31.0 +/= 3.0 vs. 43.0 +/- 1.9%) but was higher in SHR after 4- and 8-Hz contractions (4 Hz, 52.0 +/- 4.8 vs. 43.0 +/- 3.6%; 8 Hz, 51.0 +/- 4.6 vs. 41.0 +/- 3.6%). Therefore, an excess in oxygen delivery occurs relative to oxygen use during muscle contractions in SHR. The previous and current results can be reconciled by considering the possibility that oxygen exchange is limited in SHR by a decrease in anatomic or perfused capillary density, arteriovenular shunting of blood, or decreased transit time of red blood cells through exchange vessels.

scholarly journals Aging Additively Influences Insulin- and Insulin-Like Growth Factor-1-Mediated Endothelial Dysfunction and Antioxidant Deficiency in Spontaneously Hypertensive Rats

Biomedicines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 676
Author(s):  
Kunanya Masodsai ◽  
Yi-Yuan Lin ◽  
Sih-Yin Lin ◽  
Chia-Ting Su ◽  
Shin-Da Lee ◽  
...  
Keyword(s):  
Growth Factor ◽  
Endothelial Dysfunction ◽  
Spontaneously Hypertensive Rats ◽  
No Production ◽  
Organ Bath ◽  
Insulin Like Growth Factor ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Nos Inhibitors ◽  
Wistar Kyoto

This study aimed to investigate the aging-related endothelial dysfunction mediated by insulin and insulin-like growth factor-1 (IGF-1) and antioxidant deficiency in hypertension. Male spontaneously hypertensive rats (SHRs) and age-matched normotensive Wistar–Kyoto rats (WKYs) were randomly divided into 24-week-old (younger) and 48-week-old (older) groups, respectively. The endothelial function was evaluated by the insulin- and IGF-1-mediated vasorelaxation of aortic rings via the organ bath system. Serum levels of nitric oxide (NO), malondialdehyde (MDA), catalase, and total antioxidant capacity (TAC) were examined. The insulin- and IGF-1-mediated vasorelaxation was significantly impaired in both 24- and 48-week-old SHRs compared with age-matched WKYs and was significantly worse in the 48-week-old SHR than the 24-week-old SHR. After pretreatments of phosphoinositide 3-kinase (PI3K) or NO synthase (NOS) inhibitors, the insulin- and IGF-1-mediated vasorelaxation became similar among four groups. The serum level of MDA was significantly increased, while the NO, catalase, and TAC were significantly reduced in the 48-week-old SHR compared with the 24-week-old SHR. This study demonstrated that the process of aging additively affected insulin- and IGF-1-mediated endothelial dysfunction in SHRs, which could be partly attributed to the reduced NO production and antioxidant deficiency.

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