High blood pressure maintenance in transgenic mRen-2 vs. Lyon genetically hypertensive rats

1993 ◽  
Vol 265 (1) ◽  
pp. R180-R186 ◽  
Author(s):  
M. Lo ◽  
I. A. Medeiros ◽  
J. J. Mullins ◽  
D. Ganten ◽  
C. Barres ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Renin Angiotensin System ◽  
Renal Perfusion ◽  
Sodium Reabsorption ◽  
Sprague Dawley ◽  
Hypertensive Rats ◽  
Renal Handling ◽  
Genetically Hypertensive Rats ◽  
Pressure Natriuresis ◽  
Genetically Hypertensive

The present work was aimed to assess the factors involved in the maintenance of hypertension in adult transgenic mRen-2 (TG) rats. Special attention was paid to the renal handling of sodium, the sympathetic, and the renin-angiotensin system (RAS) activity. TG rats were compared with age-matched Lyon genetically hypertensive rats (LH), as both are of Sprague-Dawley origin. Blood pressure (BP), heart rate, and renal sympathetic nerve activity (RSNA) were recorded in conscious freely moving animals. Kidneys were isolated and single-pass perfused at different pressure levels. It was observed that the peripheral sympathetic drive was identical in TG and LH rats as indicated by their similar 24-h urinary excretion of catecholamines and methoxylated metabolites, baseline RSNA and its control by the baroreflex, and hypotensive response to ganglion-blockade. On the contrary, TG rats differed from LH rats by a more rapid excretion of an oral isotonic sodium load, a greater hypotensive and natriuretic response to furosemide, and a more marked BP response to acute RAS blockade. The TG kidney responses to stepwise changes in renal perfusion pressure (RPP) differed from those of LH rats by significantly higher perfusate flow and glomerular filtration rate. However, the pressure natriuresis curve of TG kidneys did not differ from that of LH rats because of an elevated tubular sodium reabsorption rate. These results suggest that adult TG rats, compared with LH rats, exhibit a tendency toward sodium and water retention, which may explain that despite low renal and circulating renin levels, the RAS remains involved in the maintenance of high BP in that model.

Blood Pressure in Genetically Hypertensive Rats

Hypertension ◽  
1995 ◽  
Vol 26 (3) ◽  
pp. 452-459 ◽  
Author(s):  
Anne O. Davidson ◽  
Nicholas Schork ◽  
Bryon C. Jaques ◽  
Andrew W. Kelman ◽  
Roger G. Sutcliffe ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Hypertensive Rats ◽  
Genetically Hypertensive Rats ◽  
Genetically Hypertensive

NE turnover in genetically hypertensive rats of Lyon strain. I. Brain nuclei

1988 ◽  
Vol 255 (4) ◽  
pp. H729-H735 ◽  
Author(s):  
M. Sautel ◽  
J. Sacquet ◽  
M. Vincent ◽  
J. Sassard
Keyword(s):  
Blood Pressure ◽  
Hypothalamic Nucleus ◽  
Primary Role ◽  
Hypertensive Rats ◽  
Brain Areas ◽  
Brain Nuclei ◽  
Genetically Hypertensive Rats ◽  
Low Blood Pressure ◽  
Genetically Hypertensive

Several indirect evidences of alterations in the central catecholaminergic structures were obtained in genetically hypertensive rats. Because they could be of pathogenetic value, we measured, in the present work, the in vivo turnover (TO) of norepinephrine (NE) in brain areas of 5- and 22-wk-old genetically hypertensive (LH) rats of the Lyon strain, and their simultaneously selected normotensive (LN) and low blood pressure (LL) controls. Among the changes observed, the increased TO of NE in the A2 and A6 regions of 5-wk-old LH rats and its decrease in the posteroventral hypothalamic nucleus of 22-wk-old LH animals appeared likely to compensate for hypertension. On the contrary, the decreased TO of NE in the anterior hypothalamic nucleus observed at 5 wk and in the A6 and A1 areas at 22 wk of age in LH rats could participate in the development or the maintenance of hypertension. Above all, it was postulated that the increased TO of NE found in the A7 region of 5-wk-old LH rats could play a primary role in the pathogenesis of hypertension in the Lyon model.

Pressure natriuresis during saline expansion in newborn and adult dogs

1984 ◽  
Vol 246 (6) ◽  
pp. F828-F834 ◽  
Author(s):  
L. I. Kleinman ◽  
R. O. Banks
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Perfusion Pressure ◽  
Renal Perfusion ◽  
Sodium Reabsorption ◽  
Renal Perfusion Pressure ◽  
Arterial Blood ◽  
Bilateral Carotid ◽  
Glomerular Filtrate ◽  
Pressure Natriuresis

Pressure natriuresis was studied in anesthetized saline-expanded adult (n = 10) and neonatal (n = 23) dogs. One group (protocol B) received ethacrynic acid and amiloride to block distal nephron function. Studies in the other group (protocol A) were done without diuretics. Renal arterial blood pressure was raised by bilateral carotid artery occlusion. Renal perfusion pressure was then lowered in steps by partially occluding the aorta proximal to the renal arteries. In protocol B carotid occlusion was associated with an increase in both absolute and fractional sodium excretion by adult and newborn dogs. Moreover, there was significant negative correlation (P less than 0.01) between absolute change in renal arterial pressure and change in tubular reabsorption of sodium per milliliter glomerular filtrate for both age groups. For each mmHg increase in blood pressure there was greater inhibition of sodium reabsorption in the puppy (0.55 mueq/ml glomerular filtrate) than in the adult (0.18 mueq/ml, P less than 0.05). In protocol A puppies, the inhibition of sodium reabsorption due to increases in renal perfusion pressure was less than that occurring in protocol B, indicating that some of the sodium escaping proximal nephron reabsorption was reabsorbed distally. Results of these studies indicate that during saline expansion pressure natriuresis is primarily a proximal tubular event, and the sensitivity of the proximal tubule to changes in renal arterial blood pressure is greater in the newborn than the adult kidney.

Characterization of renal aldosterone receptors in genetically hypertensive rats

1993 ◽  
Vol 264 (2) ◽  
pp. F286-F291 ◽  
Author(s):  
M. Horiuchi ◽  
H. Nishiyama ◽  
J. Hama ◽  
T. Takenaka ◽  
H. Kondo ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Urine Volume ◽  
Plasma Aldosterone ◽  
Type I ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Receptor Complexes ◽  
Genetically Hypertensive Rats ◽  
Wistar Kyoto ◽  
Genetically Hypertensive

To investigate the aldosterone responsiveness of genetically hypertensive rats, we compared characteristics of renal cytosolic aldosterone receptors from the M strain of stroke-prone, spontaneously hypertensive rats (M-SHRSP) with normotensive Wistar-Kyoto rats (WKY). In M-SHRSP, blood pressure was elevated significantly at 6 wk of age, when their plasma aldosterone concentrations were similar to those in WKY. Decreases in urine volume and sodium excretion were also observed in M-SHRSP. At 10 wk of age, M-SHRSP plasma aldosterone concentrations became significantly higher than those in WKY. On the other hand, the concentration of renal cytosolic aldosterone receptors (type I, aldosterone specific) had already increased at 6 wk of age in M-SHRSP, with no difference in affinity, and levels remained increased thereafter. There were no significant differences in molecular weights or ionic charges of either "activated" or "non-activated" aldosterone-receptor complexes between M-SHRSP and WKY, indicating that the molecular properties were similar in both groups. These results suggest that the increased concentration of aldosterone receptors in the kidneys of M-SHRSP might increase their aldosterone responsiveness and contribute to the development of high blood pressure in these animals.

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