scholarly journals Lymphocyte responses exacerbate angiotensin II-dependent hypertension

2010 ◽  
Vol 298 (4) ◽  
pp. R1089-R1097 ◽  
Author(s):  
Steven D. Crowley ◽  
Young-Soo Song ◽  
Eugene E. Lin ◽  
Robert Griffiths ◽  
Hyung-Suk Kim ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Sodium Excretion ◽  
Kidney Injury ◽  
Scid Mice ◽  
Prostaglandin E ◽  
Ang Ii ◽  
Blood Pressure Elevation ◽  
Cox 2 ◽  
Lymphocyte Responses

Activation of the immune system by ANG II contributes to the pathogenesis of hypertension, and pharmacological suppression of lymphocyte responses can ameliorate hypertensive end-organ damage. Therefore, to examine the mechanisms through which lymphocytes mediate blood pressure elevation, we studied ANG II-dependent hypertension in scid mice lacking lymphocyte responses and wild-type controls. Scid mice had a blunted hypertensive response to chronic ANG II infusion and accordingly developed less cardiac hypertrophy. Moreover, lymphocyte deficiency led to significant reductions in heart and kidney injury following 4 wk of angiotensin. The muted hypertensive response in the scid mice was associated with increased sodium excretion, urine volumes, and weight loss beginning on day 5 of angiotensin infusion. To explore the mechanisms underlying alterations in blood pressure and renal sodium handling, we measured gene expression for vasoactive mediators in the kidney after 4 wk of ANG II administration. Scid mice and controls had similar renal expression for interferon-γ, interleukin-1β, and interleukin-6. By contrast, lymphocyte deficiency (i.e., scid mice) during ANG II infusion led to upregulation of tumor necrosis factor-α, endothelial nitric oxide synthase (eNOS), and cyclooxygenase-2 (COX-2) in the kidney. In turn, this enhanced eNOS and COX-2 expression in the scid kidneys was associated with exaggerated renal generation of nitric oxide, prostaglandin E2, and prostacyclin, all of which promote natriuresis. Thus, the absence of lymphocyte activity protects from hypertension by allowing blood pressure-induced sodium excretion, possibly via stimulation of eNOS- and COX-2-dependent pathways.

Abstract P035: Prostaglandin Ep4 Receptors In Kidney Epithelial Cells Promote Resistance To Hypertension

Hypertension ◽  
2020 ◽  
Vol 76 (Suppl_1) ◽  
Author(s):  
Ting Yang ◽  
Chengcheng Song ◽  
Matthew A Sparks ◽  
Beverly H Koller ◽  
Thomas M Coffman
Keyword(s):  
Blood Pressure ◽  
Epithelial Cells ◽  
Collecting Duct ◽  
Weight Ratio ◽  
Pressure Control ◽  
Prostaglandin E ◽  
Ang Ii ◽  
Blood Pressure Elevation ◽  
Adult Mice ◽  
Kidney Epithelial Cells

A role for prostanoids in blood pressure control is demonstrated by clinical studies showing that use of nonsteroidal anti-inflammatory drugs, which block all the prostanoid production, is associated with hypertension. Prostaglandin E 2 (PGE 2 ) is a major prostanoid produced by the kidney and its actions are mediated by four E-prostanoid (EP) receptors: EP1-EP4. In previous studies, we found that conditional deletion of EP4R from all tissues in adult mice dramatically exaggerates Ang II-dependent hypertension, suggesting a powerful effect of EP4R to resist blood pressure elevation. We also found that elimination of EP4R from vascular smooth muscle cells did not affect severity of hypertension, indicating other cellular targets of PGE 2 must mediate this anti-hypertensive effect. Here we report studies examining actions of EP4R in two additional candidate cell lineages: macrophages and kidney epithelial cells, which have both been implicated in hypertension pathogeneses. Cell-specific deletion of EP4R was accomplished by crossing mice bearing a conditional EP4 allele ( EP4 flox ) with mouse lines carrying a LyzM-Cre + transgene expressing in macrophages (MACKOs) or tetracycline-inducible Pax8-rtTA + TetO-Cre + transgene driving expression in renal tubular epithelial cells (RTKOs). Elimination of EP4R from macrophages in MACKOs had minimal effects on baseline BP and salt sensitivity, and responses to chronic Ang II infusion were virtually identical in MACKOs and controls (138±3 vs 133±2 mm Hg; n=14/group). By contrast, absence of EP4R from kidney epithelia in RTKOs caused significant augmentation of Ang II-induced hypertension compared to Controls (average MAP: 145±4 vs. 135±3 mmHg, p=0.03; MAP increase from baseline: 31±2 vs. 20±3 mmHg, p=0.02). The increased severity of hypertension in RTKOs was associated with exaggerated cardiac hypertrophy relative to controls (heart:body weight ratio 8.6±1.5 vs. 7.3±1.2 mg/g; p=0.03). Our findings suggest that kidney epithelial cells, but not macrophages, are critical targets of PGE 2 acting via EP4R to oppose the development of hypertension. As collecting duct is the major site of EP4R expression in renal epithelia, this may reflect actions of EP4R to modulate key sodium transporters in this nephron segment.

Volume expansion during NOS substrate donation with l-arginine: regulatory offsetting of renal response?

2002 ◽  
Vol 282 (4) ◽  
pp. R1149-R1155 ◽  
Author(s):  
Jens Lundbæk Andersen ◽  
Niels C. F. Sandgaard ◽  
Peter Bie
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Sodium Excretion ◽  
Volume Expansion ◽  
Free Water ◽  
Urine Osmolality ◽  
Urine Flow ◽  
Ang Ii ◽  
Free Water Clearance ◽  
Arterial Blood

The responses to infusion of nitric oxide synthase substrate (l-arginine 3 mg · kg−1 · min−1) and to slow volume expansion (saline 35 ml/kg for 90 min) alone and in combination were investigated in separate experiments. l-Arginine left blood pressure and plasma ANG II unaffected but decreased heart rate (6 ± 2 beats/min) and urine osmolality, increased glomerular filtration rate (GFR) transiently, and caused sustained increases in sodium excretion (fourfold) and urine flow (0.2 ± 0.0 to 0.7 ± 0.1 ml/min). Volume expansion increased arterial blood pressure (102 ± 3 to 114 ± 3 mmHg), elevated GFR persistently by 24%, and enhanced sodium excretion to a peak of 251 ± 31 μmol/min, together with marked increases in urine flow, osmolar and free water clearances, whereas plasma ANG II decreased (8.1 ± 1.7 to 1.6 ± 0.3 pg/ml). Combined volume expansion and l-arginine infusion tended to increase arterial blood pressure and increased GFR by 31%, whereas peak sodium excretion was enhanced to 335 ± 23 μmol/min at plasma ANG II levels of 3.0 ± 1.1 pg/ml; urine flow and osmolar clearance were increased at constant free water clearance. In conclusion, l-arginine 1) increases sodium excretion, 2) decreases basal urine osmolality, 3) exaggerates the natriuretic response to volume expansion by an average of 50% without persistent changes in GFR, and 4) abolishes the increase in free water clearance normally occurring during volume expansion. Thus l-arginine is a natriuretic substance compatible with a role of nitric oxide in sodium homeostasis, possibly by offsetting/shifting the renal response to sodium excess.

scholarly journals Sargassum fulvellumProtects HaCaT Cells and BALB/c Mice from UVB-Induced Proinflammatory Responses

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Chan Lee ◽  
Gyu Hwan Park ◽  
Eun Mi Ahn ◽  
Chan-Ik Park ◽  
Jung-Hee Jang
Keyword(s):  
Nitric Oxide ◽  
Ethanol Extract ◽  
Prostaglandin E ◽  
Hacat Cells ◽  
Uvb Irradiation ◽  
Proinflammatory Mediators ◽  
Sargassum Fulvellum ◽  
Cox 2 ◽  
Anti Inflammatory ◽  
Skin Damages

Ultraviolet (UV) radiation has been reported to induce cutaneous inflammation such as erythema and edema via induction of proinflammatory enzymes and mediators.Sargassum fulvellumis a brown alga of Sargassaceae family which has been demonstrated to exhibit antipyretic, analgesic, antiedema, antioxidant, antitumor, fibrinolytic, and hepatoprotective activities. The purpose of this study is to investigate anti-inflammatory effects of ethylacetate fraction of ethanol extract ofSargassum fulvellum(SFE-EtOAc) in HaCaT keratinocytes and BALB/c mice. In HaCaT cells, SFE-EtOAc effectively inhibited UVB-induced cytotoxicity (60 mJ/cm2) and the expression of proinflammatory proteins such as cyclooxygenase-2 (COX-2), tumor necrosis factor-α(TNF-α), and inducible nitric oxide synthase (iNOS). Furthermore, SFE-EtOAc significantly reduced UVB-induced production of proinflammatory mediators including prostaglandin E2(PGE2) and nitric oxide (NO). In BALB/c mice, topical application of SFE-EtOAc prior to UVB irradiation (200 mJ/cm2) effectively suppressed the UVB-induced protein expression of COX-2, iNOS, and TNF-αand subsequently attenuated generation of PGE2and NO as well. In another experiment, SFE-EtOAc pretreatment suppressed UVB-induced reactive oxygen species production and exhibited an antioxidant potential by upregulation of antioxidant enzymes such as catalase and Cu/Zn-superoxide dismutase in HaCaT cells. These results suggest that SFE-EtOAc could be an effective anti-inflammatory agent protecting against UVB irradiation-induced skin damages.

scholarly journals Oleifolioside A, a New Active Compound, Attenuates LPS-Stimulated iNOS and COX-2 Expression through the Downregulation of NF-κB and MAPK Activities in RAW 264.7 Macrophages

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Hai Yang Yu ◽  
Kyoung-Sook Kim ◽  
Young-Choon Lee ◽  
Hyung-In Moon ◽  
Jai-Heon Lee
Keyword(s):  
Nitric Oxide ◽  
Mapk Signaling ◽  
Binding Activity ◽  
Prostaglandin E ◽  
Raw 264.7 ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Raw 264.7 Macrophages ◽  
Dendropanax Morbifera ◽  
Cox 2

Oleifolioside A, a new triterpenoid compound isolated fromDendropanax morbiferaLeveille (D. morbifera), was shown in this study to have potent inhibitory effects on lipopolysaccharide (LPS-)stimulated nitric oxide (NO) and prostaglandin E2(PGE2) production in RAW 264.7 macrophages. Consistent with these findings, oleifolioside A was further shown to suppress the expression of LPS-stimulated inducible nitric oxide synthase (iNOS) and cyclooxigenase-2 (COX-2) in a dose-dependent manner at both the protein and mRNA levels and to significantly inhibit the DNA-binding activity and transcriptional activity of NF-κB in response to LPS. These results were found to be associated with the inhibition of the degradation and phosphorylation of IκB-αand subsequent translocation of the NF-κB p65 subunit to the nucleus. Inhibition of NF-κB activation by oleifolioside A was also shown to be mediated through the prevention of p38 MAPK and ERK1/2 phosphorylation. Taken together, our results suggest that oleifolioside A has the potential to be a novel anti-inflammatory agent capable of targeting both the NF-κB and MAPK signaling pathways.

scholarly journals Genetic deletion of AT1a receptors attenuates intracellular accumulation of ANG II in the kidney of AT1a receptor-deficient mice

2007 ◽  
Vol 293 (2) ◽  
pp. F586-F593 ◽  
Author(s):  
Xiao C. Li ◽  
L. Gabriel Navar ◽  
Yuan Shao ◽  
Jia L. Zhuo
Keyword(s):  
Blood Pressure ◽  
Sodium Excretion ◽  
Rat Kidney ◽  
Systolic Pressure ◽  
Weight Ratio ◽  
Urinary Sodium Excretion ◽  
Urinary Sodium ◽  
Ang Ii ◽  
Wild Type ◽  
Deficient Mice

We and others have previously shown that high levels of ANG II are accumulated in the rat kidney via a type 1 (AT1) receptor-mediated mechanism, but it is not known which AT1 receptor is involved in this process in rodents. We tested the hypothesis that AT1a receptor-deficient mice (Agtr1a−/−) are unable to accumulate ANG II intracellularly in the kidney because of the absence of AT1a receptor-mediated endocytosis. Adult male wild-type (Agtr1a+/+), heterozygous (Agtr1a+/−), and Agtr1a−/− were treated with vehicle, ANG II (40 ng/min ip via osmotic minipump), or ANG II plus the AT1 antagonist losartan (10 mg·kg−1·day−1 po) for 2 wk. In wild-type mice, ANG II induced hypertension (168 ± 4 vs. 113 ± 3 mmHg, P < 0.001), increased kidney-to-body weight ratio ( P < 0.01), caused pressure natriuresis ( P < 0.05), and elevated plasma and whole kidney ANG II levels ( P < 0.001). Concurrent administration of ANG II with losartan attenuated these responses to ANG II. In contrast, Agtr1a−/− mice had lower basal systolic pressures ( P < 0.001), smaller kidneys with much fewer AT1b receptors ( P < 0.001), higher basal 24-h urinary sodium excretion ( P < 0.01), as well as basal plasma and whole kidney ANG II levels ( P < 0.01). However, intracellular ANG II levels in the kidney were lower in Agtr1a−/− mice. In Agtr1a−/− mice, ANG II slightly increased systolic pressure ( P < 0.05) but had no effect on the kidney weight, urinary sodium excretion, and whole kidney ANG II levels. Losartan restored systolic pressure to basal levels and decreased whole kidney ANG II levels by ∼20% ( P < 0.05). These results demonstrate a predominant role of AT1a receptors in blood pressure regulation and in the renal responses to long-term ANG II administration, that AT1b receptors may play a limited role in blood pressure control and mediating intrarenal ANG II accumulation in the absence of AT1a receptors.

scholarly journals Resveratrol Supplementation Prevents Hypertension in Hypertensive Pregnant Rats by Increasing Sodium Excretion and Serum Nitric Oxide Level

2020 ◽  
Vol 2020 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaowen Jia ◽  
Rong Zhang ◽  
Jinzhu Guo ◽  
Hua Yue ◽  
Qiuxia Liu ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Rat Model ◽  
Sodium Excretion ◽  
Urine Volume ◽  
Noninvasive Blood Pressure ◽  
Blood Pressure Lowering Effect ◽  
Pregnant Rat ◽  
Salt Diet ◽  
Nitric Oxide Level

Background. Pregnancy-induced hypertension (PIH) remains a major cause of morbidity and mortality in pregnancy worldwide. This study was designed to study the blood pressure-lowering effect of resveratrol (RES) in a salt-induced hypertensive pregnant rat model. Methods. Forty female Sprague Dawley (SD) rats were randomized into 4 groups: Normal Preg (0.9% salt diet), Normal Preg + RES (0.9% salt diet plus daily oral RES for 4 weeks), Salt Preg (8% salt diet), and Salt Preg + RES (8% salt diet plus daily oral RES for 4 weeks). Noninvasive blood pressure was recorded on gestational days 7 and 14. On the gestational day 19, foetuses were weighed, and blood and urine samples were harvested for electrolytes and biochemical assays. Results. RES significantly reduced SBP, DBP, and MAP on gestational days 7 and 14 in the Salt Preg + RES group compared to the Salt Preg group (all P<0.05). Compared to the Salt Preg group, the foetal weight, serum NO level, urinary sodium, and 24 hour urine volume were significantly increased in the Salt Preg + RES group (all P<0.05). On the contrary, the levels of serum urea, serum creatinine, and urinary protein were significantly decreased in the Salt Preg + RES group compared to the Salt Preg group (all P<0.05). Conclusions. RES decreases blood pressure in a hypertensive pregnant rat model. Increasing sodium excretion and serum nitric oxide level might be, at least part of, the underlying mechanisms.

EFFECTS OF 9-ALPHA-FLUOROHYDROCORTISONE ON BLOOD PRESSURE, PLASMA VOLUME, AND SODIUM, POTASSIUM AND WATER BALANCE IN RATS

1974 ◽  
Vol 76 (3) ◽  
pp. 539-555 ◽  
Author(s):  
D. Haack ◽  
E. Hackenthal ◽  
E. Homsy ◽  
B. Möhring ◽  
J. Möhring
Keyword(s):  
Blood Pressure ◽  
Water Balance ◽  
Plasma Volume ◽  
Sodium Excretion ◽  
Urinary Sodium Excretion ◽  
Sodium Concentration ◽  
Urinary Sodium ◽  
Blood Pressure Elevation ◽  
High Doses ◽  
Water And Sodium Excretion

ABSTRACT In normal rats on a standard sodium diet, the administration of 9-alpha-fluorohydrocortisone (9aFF) induced a rapid increase of blood pressure in parallel to an increase of plasma volume. Water and potassium balances became negative. Urinary sodium excretion remained unchanged or increased after high doses, whereas urinary sodium concentration and faecal sodium excretion were reduced. The diurnal rhythm of water and sodium excretion changed: during the night-period, renal water and sodium excretion were diminished, whereas during the day-period both were enhanced. Thus, some effects of 9aFF on electrolyte and water balance are similar to those of DOC, while other effects are similar to those of cortisone. It is postulated that a shift of fluid from intracellular to extracellular compartments, which increases plasma volume, is of critical importance for the 9aFF-induced blood pressure elevation in rats.

scholarly journals Inhibitory Effects of Traditional Herbal Formula Pyungwi-San on Inflammatory ResponseIn VitroandIn Vivo

2013 ◽  
Vol 2013 ◽  
pp. 1-19 ◽  
Author(s):  
Ji Young Cha ◽  
Ji Yun Jung ◽  
Jae Yup Jung ◽  
Jong Rok Lee ◽  
Il Je Cho ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Inflammatory Mediators ◽  
Raw 264.7 Cells ◽  
Prostaglandin E ◽  
Herbal Formula ◽  
Paw Edema ◽  
Cox 2 ◽  
Anti Inflammatory

Pyungwi-san (PWS) is a traditional basic herbal formula. We investigated the effects of PWS on induction of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), pro-inflammatory cytokines (interleukin-6 (IL-6) and tumor necrosis factor-α(TNF-α)) and nuclear factor-kappa B (NF-κB) as well as mitogen-activated protein kinases (MAPKs) in lipopolysaccharide-(LPS-) induced Raw 264.7 cells and on paw edema in rats. Treatment with PWS (0.5, 0.75, and 1 mg/mL) resulted in inhibited levels of expression of LPS-induced COX-2, iNOS, NF-κB, and MAPKs as well as production of prostaglandin E2(PGE2), nitric oxide (NO), IL-6, and TNF-αinduced by LPS. Our results demonstrate that PWS possesses anti-inflammatory activities via decreasing production of pro-inflammatory mediators through suppression of the signaling pathways of NF-κB and MAPKs in LPS-induced macrophage cells. More importantly, results of the carrageenan-(CA-) induced paw edema demonstrate an anti-edema effect of PWS. In addition, it is considered that PWS also inhibits the acute edematous inflammations through suppression of mast cell degranulations and inflammatory mediators, including COX-2, iNOS and TNF-α. Thus, our findings may provide scientific evidence to explain the anti-inflammatory properties of PWSin vitroandin vivo.

scholarly journals Augmented cyclooxygenase-2 effects on renal function during varying states of angiotensin II

2010 ◽  
Vol 299 (5) ◽  
pp. F954-F962 ◽  
Author(s):  
Torrance Green ◽  
Jorge Rodriguez ◽  
L. Gabriel Navar
Keyword(s):  
Blood Flow ◽  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Plasma Flow ◽  
Sodium Excretion ◽  
Filtration Rate ◽  
Renal Plasma Flow ◽  
Ang Ii ◽  
Series Of Experiments ◽  
Cox 2

Nonsteroidal anti-inflammatory drug usage has long revealed renoprotective prostaglandin actions on the renal microvasculature during increased pressor hormone influence, but whether increased cyclooxygenase (COX)-2 expression supports prostaglandin vasodilatory influence by interfering with the actions of ANG II remains unresolved. Therefore, we tested the hypothesis that COX-2 inhibition causes hemodynamic and excretory effects that are increased in proportion to ANG II activity. In anesthetized Sprague-Dawley rats having augmented cortical COX-2 expression but different ANG II activity, we conducted renal clearance experiments during acute inhibition of COX-2 with nimesulide (NMSLD) and inhibition of COX-1 with SC-560. In one series of experiments, acute captopril [acute angiotensin-converting enzyme (ACE) inhibitor (aACEi)] was administered alone ( n = 13) or in combination with chronic captopril [chronic ACEi (cACEi)] pretreatment ( n = 19). In another series of experiments, rats were fed a normal-sodium [0.4% (NS), n = 12] or a low-sodium [0.03% (LS), n = 18] diet. NMSLD did not alter mean arterial blood pressure in any group but, in the LS and cACEi groups, decreased renal plasma flow (from 3.99 ± 0.33 to 2.85 ± 0.26 and from 4.30 ± 0.19 to 3.22 ± 0.21 ml·min−1·g−1), cortical blood flow (−12 ± 8% and −13 ± 4%), and glomerular filtration rate (from 0.88 ± 0.04 to 0.65 ± 0.05 and from 0.95 ± 0.07 to 0.70 ± 0.05 ml·min−1·g−1). In contrast, medullary blood flow (MBF) was significantly decreased by COX-2 inhibition in NS (−24 ± 5%), LS (−27 ± 8%), aACEi (−16 ± 3.8%), and cACEi (−24 ± 4.2%) groups. Absolute and fractional sodium excretion rates were unchanged by NMSLD, except in the LS group (0.75 ± 0.05 μeq/min and 0.43 ± 0.15% and 0.51 ± 0.06 μeq/min and 0.26 ± 0.10%). SC-560 did not augment the effects of NMSLD. These results demonstrate an augmented COX-2-mediated vasodilation that is not contingent on ANG II, in contrast to COX-2-mediated augmented sodium excretion, where ANG II activity is requisite. Furthermore, the COX-2 effects on MBF are not contingent on ANG II or changes in cortical microvascular responses. These results reflect COX-2 continual regulation of MBF and adaptive opposition to ANG II prohypertensinogenic effects on renal plasma flow, cortical blood flow, glomerular filtration rate, and absolute and fractional sodium excretion.

Renal and Cardiovascular Effects of Exogenous Insulin in Healthy Volunteers

1991 ◽  
Vol 80 (3) ◽  
pp. 219-225 ◽  
Author(s):  
R. O. B. Gans ◽  
L. v.d. Toorn ◽  
H. J. G. Bilo ◽  
J. J. P. Nauta ◽  
R. J. Heine ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Analysis Of Variance ◽  
Sodium Excretion ◽  
Circadian Variation ◽  
Cardiovascular Effects ◽  
Insulin Dosage ◽  
Angiotensin I ◽  
Blood Pressure Elevation ◽  
Fractional Sodium Excretion

1. Renal and cardiovascular effects of three dosages of insulin [50 (Ins I), 300 (Ins II) and 500 (Ins III) m-units h−1 kg−1] were investigated in healthy males by using a euglycaemic clamp technique. On separate days, control experiments were carried out to correct for any circadian variation in the variables studied. 2. All three insulin dosages resulted in a marked decline in fractional sodium excretion (actual experiments: basal, 0.95 ± 0.15%, Ins I, 0.79 ± 0.10%, Ins II, 0.80 ± 0.12%, Ins III, 0.84 ± 0.08%; control experiments: basal, 0.96 ± 0.10%, Ins I, 1.20 ± 0.12%, Ins II, 1.53 ± 0.15%, Ins III, 1.43 ± 0.10%; means ± sem, P < 0.005, analysis of variance). With the highest insulin dosage, the reduction in fractional sodium excretion tended to be less striking. This coincided with a rise in heart rate, pulse pressure and pulse rate-systolic blood pressure product (double product). Although blood pressure itself did not change, systolic blood pressure also tended to increase (actual experiments: basal, 133 ± 5 mmHg, Ins I, 132 ± 5 mmHg, Ins II, 139 ± 5 mmHg, Ins III, 143 ± 4 mmHg; control experiments: basal, 128 ± 3 mmHg, Ins I, 129 ± 3 mmHg, Ins II, 130 ± 3 mmHg, Ins III, 133 ± 3 mmHg; means ± sem, P = 0.09, analysis of variance). There was a positive correlation between the change in fractional sodium excretion and the change in systolic blood pressure over control values (r = 0.696, P < 0.028). At a rise in systolic blood pressure of 18 mmHg, the sodium-retaining effect of insulin appeared to be offset. A shift of the pressure-natriuresis relation to the right is suggested. 3. Plasma catecholamines did not change. Plasma renin activity increased from 1.11 ± 0.17 (basal) to 2.13 ± 0.31 (Ins III) pmol of angiotensin I h−1 ml−1; on the control day, a decline from 1.28 ± 0.24 (basal) to 0.81 ± 0.13 (Ins III) pmol of angiotensin I h−1 ml−1 was noted (P < 0.001). Despite this rise no concomitant rise in plasma aldosterone occurred. 4. Chronic hyperinsulinaemia may lead to blood pressure elevation in the long-term if it is postulated that resistance to the glucose-lowering effect of insulin is absent for the effects of insulin on the kidney and the cardiovascular system.

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