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Association of elevated plasma aldosterone-to-renin ratio with future cardiovascular events in patients with essential hypertension. J Hypertens 2012; 30:2322-30. [DOI: 10.1097/hjh.0b013e328359862d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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2
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Kim CH, Vaziri ND. Hypertension promotes integrin expression and reactive oxygen species generation by circulating leukocytes. Kidney Int 2005; 67:1462-70. [PMID: 15780098 DOI: 10.1111/j.1523-1755.2005.00223.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Compelling evidence has emerged pointing to the role of oxidative stress in the pathogenesis of hypertension (HTN) in experimental animals. Excess production of reactive oxygen species (ROS) in the renal and vascular tissues has been shown to raise arterial pressure via inactivation of nitric oxide and generation of isoprostanes. Accumulation of inflammatory cells in the renal interstitium has been shown to increase ROS generation in the kidneys of hypertensive animals. In addition, considerable evidence has emerged pointing to spontaneous activation of circulating leukocytes in animals and humans with hereditary HTN. This study was designed to explore whether induction of HTN in genetically normal animals can lead to spontaneous activation and ROS production in circulating leukocytes. METHODS Integrin expression, superoxide, and hydrogen peroxide production were assessed by flow cytometry in the circulating and splenic leukocytes of Sprague-Dawley rats rendered hypertensive by abdominal aorta banding above the renal arteries, and in sham-operated control rats. RESULTS The hypertensive animals studied 4 weeks after abdominal aorta banding exhibited a significant increase in superoxide and H(2)O(2) production in the circulating granulocyte, and a marked increase in H(2)O(2) production in the blood and splenic helper and cytotoxic T-lymphocytes. This was coupled with a significant up-regulation of CD18 and CD11a in splenic helper T-cells and cytotoxic T cells, and of CD18 in the circulating helper T cells. CONCLUSION Induction of HTN in genetically normotensive rats causes a spontaneous increase in ROS generation in the circulating and splenic leukocytes. This phenomenon can contribute to systemic oxidative stress, inflammation, cardiovascular and renal complications in hypertensive animals.
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Affiliation(s)
- Choong H Kim
- Division of Nephrology and Hypertension, University of California, Irvine, Irvine, California 92868, USA
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3
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Lin PH, Windhauser MM, Plaisted CS, Hoben KP, McCullough ML, Obarzanek E. The Linear Index Model for establishing nutrient goals in the Dietary Approaches to Stop Hypertension trial. DASH Collaborative Research Group. JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION 1999; 99:S40-4. [PMID: 10450293 DOI: 10.1016/s0002-8223(99)00415-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Establishing target levels of nutrients in feeding studies presents a challenge to dietitians. Although researchers studying energy-containing nutrients, such as protein and fat, commonly establish target levels according to body weight or as a percentage of energy, it is less clear how to establish levels of micronutrients. Typically, a constant target level is used regardless of energy requirements. Alternatively, nutrients could be provided at a fixed level per 1,000 kcal. Such an approach, however, could result in absolute levels of nutrient intakes that are difficult to achieve through foods alone, particularly for persons with high energy requirements. This report describes the Linear Index Model, a new approach for establishing target levels of selected micronutrients in the Dietary Approaches to Stop Hypertension trial. This model indexes micronutrient levels to energy levels to achieve a linear range of targeted intake in proportion to the energy intake. The Linear Index Model has several benefits: it takes advantage of indexing nutrients according to energy requirements, thus providing levels of nutrient intakes that can be readily achieved by foods; it is based on population consumption data, thus providing a realistic range of intakes for the experimental conditions; and it ensures distinct contrasts in experimental conditions. The Linear Index Model is a feasible and practical approach for establishing target levels of nutrients in feeding studies.
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Affiliation(s)
- P H Lin
- Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
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4
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Hojo M, Suthanthiran M, Helseth G, August P. Lymphocyte intracellular free calcium concentration is increased in preeclampsia. Am J Obstet Gynecol 1999; 180:1209-14. [PMID: 10329879 DOI: 10.1016/s0002-9378(99)70618-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES We tested 2 hypotheses: (1) Preeclampsia is characterized by an increase in intracellular free calcium concentration in lymphocytes. (2) Levels of intracellular free calcium are influenced by the calcium concentration in the extracellular milieu or by parathyroid hormone. STUDY DESIGN Intracellular free calcium concentrations were measured in 4 groups of women: nonpregnant women (n = 25), normotensive pregnant women (n = 30), pregnant women with chronic hypertension (n = 15), and women with preeclampsia (n = 15). Intracellular free calcium concentration was measured in the basal state, at varying extracellular calcium ion concentrations, and in the presence of exogenous parathyroid hormone. RESULTS Women with preeclampsia had the highest basal lymphocyte intracellular free calcium concentration (121 +/- 7 nmol/L, mean +/- SEM) compared with normotensive pregnant women during the third trimester (94 +/- 3 nmol/L, P <.001) and pregnant women in the third trimester with chronic hypertension (100 +/- 3 nmol/L, P <.01). During the third trimester normotensive women and women with chronic hypertension had significantly higher basal intracellular free calcium concentrations than were found in women during the first trimester. Exposure of lymphocytes to an extracellular milieu of low calcium concentration resulted in an increase in intracellular free calcium concentration. Incubation with parathyroid hormone had no effect on intracellular free calcium concentration. CONCLUSIONS Lymphocyte intracellular free calcium concentration is increased in preeclampsia and not in chronic hypertensive pregnancy and is greater during the third trimester than during the first trimester. Extracellular calcium depletion increases lymphocyte intracellular free calcium concentration. These data support the idea that a calcium deficit leading to an increased intracellular free calcium concentration during late pregnancy contributes to the pathogenesis of preeclampsia.
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Affiliation(s)
- M Hojo
- Department of Medicine, Cornell University Medical College, New York, New York, USA
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5
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Horiguchi M, Kimura M, Skurnick J, Aviv A. Parameters of lymphocyte Na+-Ca2+ regulation and blood pressure: the gender effect. Hypertension 1998; 32:869-74. [PMID: 9822446 DOI: 10.1161/01.hyp.32.5.869] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Alterations in cellular Ca2+ and Na+ regulation play a role in the pathogenesis of essential hypertension. Using peripheral lymphocytes from 68 normal persons, we observed the following relationships for major cellular Ca2+ regulatory parameters. Among men and women, Na+-Ca2+ exchanger activity was positively correlated with the resting cytosolic free Ca2+ ([Ca2+]c) (r=0.43, P=0.0003), and the resting [Ca2+]c was positively correlated with cytosolic Na+ ([Na+]c) (r=0.50, P=0.0001). For men only, store-operated Ca2+ entry was positively correlated with Na+-Ca2+ exchanger activity (r=0.63, P=0.0001). In addition, systolic and diastolic blood pressures were positively correlated with [Na+]c in men (r=0.53, P=0.001, and r=0. 41, P=0.017, respectively) but not in women (r=0.30, P=0.088, and r=0.24, P=0.17, respectively). Some of the relationships between cellular and blood pressure parameters were confounded by serum triglycerides. These observations indicate a gender effect on cellular Ca2+-Na+ regulation and its relationship with blood pressure.
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Affiliation(s)
- M Horiguchi
- Hypertension Research Center and the Department of Preventive Medicine and Community Health, University of Medicine and Dentistry of NJ, New Jersey Medical School, Newark, NJ, USA
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6
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Hiraga H, Oshima T, Yoshimura M, Matsuura H, Kajiyama G. Abnormal platelet Ca2+ handling accompanied by increased cytosolic free Mg2+ in essential hypertension. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:R574-9. [PMID: 9688695 DOI: 10.1152/ajpregu.1998.275.2.r574] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
To test the hypothesis that abnormal platelet Ca2+ handling in essential hypertension results from cellular Mg2+ deficiency, cytosolic free Mg2+ concentration ([Mg2+]i) and Ca2+ metabolism were studied in mag-fura 2 and fura 2-loaded platelets from 30 essential hypertensive patients and 30 sex- and age-matched normotensive controls. Basal cytosolic free Ca2+ concentration ([Ca2+]i) and intracellular Ca2+ discharge capacity were higher in hypertensives than in normotensives (22 +/- 5 vs. 18 +/- 5 nM, P < 0.05; 743 +/- 250 vs. 624 +/- 144 nM, P < 0.05, respectively). The thrombin (0. 03-1.0 U/ml)-evoked [Ca2+]i response was also enhanced in platelets from hypertensives in both the absence and presence of extracellular Ca2+. However, basal [Mg2+]i was higher in hypertensives than in normotensives (437 +/- 110 vs. 353 +/- 85 microM, P < 0.05), whereas serum Mg2+ was similar in the two groups. These results oppose the Mg2+ deficiency hypothesis in platelets in essential hypertension.
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Affiliation(s)
- H Hiraga
- First Department of Internal Medicine and Department of Clinical Laboratory Medicine, Hiroshima University School of Medicine, Hiroshima 734, Japan
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7
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Osborne CG, McTyre RB, Dudek J, Roche KE, Scheuplein R, Silverstein B, Weinberg MS, Salkeld AA. Evidence for the relationship of calcium to blood pressure. Nutr Rev 1996; 54:365-81. [PMID: 9155209 DOI: 10.1111/j.1753-4887.1996.tb03850.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- C G Osborne
- Weinberg Group Inc., Washington, DC 20036, USA
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8
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Ono N, Oshima T, Ishida M, Ishida T, Matsuura H, Kambe M, Kajiyama G. Platelet Ca2+ is not increased in stroke-prone spontaneously hypertensive rats: comparative study with spontaneously hypertensive rats. Hypertension 1996; 27:1312-7. [PMID: 8641741 DOI: 10.1161/01.hyp.27.6.1312] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have reported that cytosolic Ca2+ concentration ([Ca2+]i) is increased in platelets from spontaneously hypertensive rats (SHR) in both basal and thrombin-stimulated conditions. To determine whether the correlation between blood pressure and cellular Ca2+ metabolism exists in stroke-prone SHR (SHRSP), we investigated Ca2+ handling using fura 2 and aggregation response in platelets of 12- to 13-week-old male SHRSP, SHR, and Wistar-Kyoto rats (WKY). Systolic pressure was highest in SHRSP and lowest in WKY (213 +/- 8, 172 +/- 7, and 135 +/- 5 mm Hg, respectively). Basal [Ca2+]i was significantly higher in SHR than WKY (45.9 +/- 4.5 versus 41.2 +/- 4.8 nmol/L, P<.05), and that in SHRSP (40.2 +/- 2.8 nmol/L) was similar to that in WKY. Thrombin (0.1 IU/mL)-stimulated [Ca2+]i rise was greater in SHR and smaller in SHRSP than in WKY in the presence of extracellular Ca2+ (530 +/- 50 and 408 +/- 52 versus 475 +/- 50 nmol/L, respectively; P<.05). The recovery rate from the peak [Ca2+]i response to thrombin was greatest in SHRSP and least in WKY. Ionomycin (5 micromol/L)-stimulated [Ca2+]i rise was similar in WKY, SHR, and SHRSP (731 +/- 97, 743 +/- 88, and 683 +/- 70 nmol/L, respectively). Thrombin-induced maximum platelet aggregation response was higher in SHR and lower in SHRSP than WKY (82 +/- 4 percent and 61 +/- 15 percent versus 73 +/- 6 percent, respectively; P<.05). In contrast to SHR, basal [Ca2+]i in SHRSP was similar to that in WKY, and thrombin-stimulated [Ca2+]i was attenuated. These result suggest that platelet Ca2+ handling differs between SHR substrains and that an increased [Ca2+]i is not obligatory in genetically hypertensive rats.
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Affiliation(s)
- N Ono
- First Department of Internal Medicine, Hiroshima University School of Medicine, Japan
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9
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Higashi Y, Oshima T, Watanabe M, Matsuura H, Kajiyama G. Renal response to L-arginine in salt-sensitive patients with essential hypertension. Hypertension 1996; 27:643-8. [PMID: 8613217 DOI: 10.1161/01.hyp.27.3.643] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
This study examined whether disturbances in nitric oxide formation contribute to renal dysfunction in salt-sensitive essential hypertensive patients. We evaluated the effects of intravenous administration of L-arginine (500 mg/kg given over 30 minutes) on systemic and renal hemodynamics in 23 patients with mild essential hypertension during 1 week of a low NaCl diet (50 mmol/d) followed by 1 week of a high NaCl diet (340 mmol/d). Patients were classified as salt sensitive (n=10) or salt resistant (n=13) based on salt-induced changes in their blood pressures. Salt loading increased renal vascular resistance but not renal plasma flow in salt-sensitive patients. The L-arginine-induced renovascular relaxation was significantly reduced by a high NaCl diet (renal vascular resistance: low NaCl -12.4 +/- 2.3% versus high NaCl -7.1 +/- 1.8%, P < .001) in salt-sensitive patients, whereas it was unchanged in salt-resistant patients. The increase in plasma cGMP in response to L-arginine was also reduced by a high NaCl diet in the salt-sensitive patients (low NaCl 49 +/- 7% versus high NaCl 36 +/- 8%, P < .05) but not in the salt-resistant patients (low NaCl 51 +/- 6% versus high NaCl 58 +/- 6%). These findings suggest that NaCl loading in salt-sensitive patients with mild essential hypertension reduces the ability of L-arginine to produce nitric oxide in the endothelium of the renal vasculature.
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Affiliation(s)
- Y Higashi
- First Department of Internal Medicine, Hiroshima University School of Medicine, Japan
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10
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Balasubramanyam M, Rohowsky-Kochan C, Reeves JP, Gardner JP. Na+/Ca2+ exchange-mediated calcium entry in human lymphocytes. J Clin Invest 1994; 94:2002-8. [PMID: 7962546 PMCID: PMC294628 DOI: 10.1172/jci117553] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Regulation of cytosolic Ca2+ and cytosolic Na+ is critical for lymphocyte cation homeostasis and function. To examine the influence of cytosolic Na+ on Ca2+ regulation in human peripheral blood lymphocytes, Ca2+ entry and cytosolic Ca2+ (measured with fura-2) were monitored in cells in which cytosolic Na+ was increased and/or the Na+ gradient was decreased by reduction of external Na+ concentration. Ouabain-treated cells (0.1 mM for 30 min at 37 degrees C), suspended in Na(+)-free medium, showed a 30-65% increase in Ca2+ uptake compared to cells in 140 mM Na+ medium. Enhanced Ca2+ influx was entirely dependent on ouabain pretreatment and reversal of the Na+ gradient. Na pump inhibition or Na ionophore addition and subsequent exposure to Na(+)-free medium resulted in a sustained elevation of cytosolic Ca2+. As preincubation of cells in Ca(2+)-free medium further enhanced the ouabain-dependent increase in cytosolic Ca2+, the effects of the microsomal Ca(2+)-ATPase inhibitor thapsigargin on Ca2+ influx and cytosolic Ca2+ were studied. Thapsigargin stimulated Ca2+ entry following ouabain pretreatment and reversal of the Na+ gradient; the effects of thapsigargin were retained in the presence of LaCl3, a potent inhibitor of store-dependent calcium influx pathways. These results show lymphocytes demonstrate Na+/Ca2+ exchange activity and suggest the Na+/Ca2+ exchanger modulates cytosolic Ca2+ following intracellular Ca2+ store depletion.
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Affiliation(s)
- M Balasubramanyam
- Hypertension Research Center, University of Medicine and Dentistry-New Jersey Medical School, Newark 07103
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11
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Wu ML, Tsai ML, Tseng YZ. DIDS-sensitive pHi regulation in single rat cardiac myocytes in nominally HCO3-free conditions. Circ Res 1994; 75:123-32. [PMID: 8013070 DOI: 10.1161/01.res.75.1.123] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The fluorescent dye 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) was used to measure pHi in the spontaneously hypertensive rat (SHR) and in normal rat cardiac myocytes under nominally HCO3-free (20 mmol/L HEPES-buffered) conditions. When only the Na-H exchanger was blocked, the intrinsic buffering power (beta i) in SHR myocytes was significantly higher than when both the Na-H exchanger and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS)-sensitive pHi regulators (the Na-HCO3 cotransporter and the Cl-HCO3 exchanger) were blocked. Similar low values for beta i were also found for normal rat myocytes in Na(+)-free conditions. In Cl(-)-free solution under nominally HCO3-free conditions, in both normal and SHR myocytes, the pHi slowly alkalinized (by 0.16 +/- 0.02 and 0.11 +/- 0.02 pH units, respectively); this alkalinization was also DIDS sensitive. The reacidification during NH4+ perfusion was inhibited 30.2 +/- 7.4% by DIDS. In addition, in the nominal absence of HCO3-, 100 mumol/L ATP acidified the pHi in both normal and SHR myocytes (by 0.21 +/- 0.03 and 0.33 +/- 0.03 pH units, respectively); this acidification was totally inhibited by 0.1 mmol/L DIDS. It has been shown, in rat cardiac myocytes, that ATP acidifies the pHi by 0.35 pH unit via stimulation of a DIDS-sensitive Cl-HCO3 exchanger in HCO3-containing solutions. Finally, we have shown, in normal cardiac myocytes, that two potent Na-H exchanger blockers, N-5-ethylisopropyl amiloride (EIPA) and N-5-methyl-N-isobutyl amiloride (MIA), only partially inhibited the pHi recovery from internal acidosis under nominally bicarbonate-free conditions. When DIDS was added at the same time as EIPA, pHi recovery from an internal acid loading was completely inhibited. Our results clearly demonstrate that in both normal and SHR cardiac myocytes, bicarbonate-dependent pHi regulators can be significantly activated under resting or acidified pHi in HEPES-buffered medium, probably because of the cellular production of CO2. The contribution of these bicarbonate-dependent pHi regulators, ie, the Na-HCO3 cotransporter and the Cl-HCO3 exchanger, cannot therefore be ignored even under nominally HCO3-free conditions.
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Affiliation(s)
- M L Wu
- Department of Physiology, Medical College, National Taiwan University, Taipei, ROC
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12
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Adachi M, Nara Y, Mano M, Ikeda K, Horie R, Yamori Y. Intralymphocytic free calcium and magnesium in stroke-prone spontaneously hypertensive rats and effects of blood pressure and various antihypertensive agents. Clin Exp Pharmacol Physiol 1993; 20:587-93. [PMID: 8222339 DOI: 10.1111/j.1440-1681.1993.tb01745.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
1. Free Ca2+ ([Ca2+]i) and Mg2+ ([Mg2+]i) were measured in peripheral lymphocytes from stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY) at the age of 5, 7 and 17 weeks, from various antihypertensive agents-treated SHRSP, and from secondary hypertensive WKY. 2. At the age of 5 weeks, no difference was observed in systolic blood pressure (SBP), or lymphocyte [Ca2+]i and [Mg2+]i between SHRSP and WKY. At the age of 7 or 17 weeks, SBP and [Ca2+]i of SHRSP were significantly higher than in WKY, and at the age of 17 weeks, [Mg2+]i of SHRSP was significantly lower than in WKY. Further, [Ca2+]i or [Mg2+]i was positively or negatively correlated to SBP, and [Mg2+]i was negatively correlated to [Ca2+]i. 3. SBP of SHRSP fell significantly after antihypertensive treatment with calcium antagonist, angiotensin-converting enzyme (ACE) inhibitor or hydralazine for 40 days. [Ca2+]i was significantly lower in calcium antagonist and hydralazine groups, and tended to be low in ACE inhibitor group. These four groups showed no difference in [Mg2+]i. 4. After 40-day administration of NG-nitro-L-arginine (L-NNA), WKY developed severe hypertension, but there were no significant differences in lymphocyte [Ca2+]i and [Mg2+]i between the L-NNA treated and non-treated groups. 5. These results suggested that increased lymphocyte [Ca2+]i and decreased [Mg2+]i observed in SHRSP are not only secondary to hypertension but possibly related to a basic genetic abnormality of divalent cation handling.
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Affiliation(s)
- M Adachi
- Department of Pathology, Shimane Medical University, Izumo, Japan
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13
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Influence of activating agents on the membrane potential of lymphocytes in patients with hypertensive disease. Bull Exp Biol Med 1993. [DOI: 10.1007/bf00847176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Oshima T, Young EW, Bukoski RD, McCarron DA. Rise and fall of agonist-evoked platelet Ca2+ in hypertensive rats. Hypertension 1991; 18:758-62. [PMID: 1743757 DOI: 10.1161/01.hyp.18.6.758] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We previously reported an enhanced peak response of intracellular free Ca2+ to thrombin in platelets of spontaneously hypertensive rats in comparison with normotensive Wistar-Kyoto rats. In the present study, we compared the platelet intracellular Ca2+ response to the receptor-linked agonist thrombin with the response to the Ca2+ ionophore ionomycin. Basal intracellular Ca2+ was higher in hypertensive platelets as was leakage of fura-2. We confirmed the previous finding that the thrombin-induced intracellular Ca2+ peak is greater in platelets of hypertensive rats and noted that the rate of recovery from peak intracellular Ca2+ is significantly greater in this model. In contrast, the peak platelet intracellular Ca2+ response to ionomycin (50 nM and 5 microM) was not different between the two strains, and the rate of recovery from the peak response was only slightly depressed in hypertensive rats after the low dose of ionomycin. Internal Ca2+ discharge capacity, assessed by the intracellular Ca2+ response to a maximal dose of ionomycin in Ca(2+)-free medium, was not different between platelets of the two strains. Thus, activated platelet intracellular Ca2+ is not altered in the hypertensive rat when the nonphysiological ionophore ionomycin is used as agonist. However, a heightened intracellular Ca2+ response is observed when the receptor-mediated agonist thrombin is used. These results are consistent with the hypothesis that differences in receptor-linked second messenger pathways underlie the altered intracellular Ca2+ response in platelets of genetically hypertensive rats and may contribute to differences both in the mobilization of Ca2+ and in its fall.
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Affiliation(s)
- T Oshima
- Division of Nephrology and Hypertension, Oregon Health Sciences University, Portland
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15
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Campese VM, Parise M, Karubian F, Bigazzi R. Abnormal renal hemodynamics in black salt-sensitive patients with hypertension. Hypertension 1991; 18:805-12. [PMID: 1743761 DOI: 10.1161/01.hyp.18.6.805] [Citation(s) in RCA: 144] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
African-Americans with essential hypertension are more prone to the development of renal failure and are frequently salt-sensitive as well. Because alterations of intrarenal hemodynamics are important in the progression of renal disease and because salt-sensitive animal models with hypertension manifest a greater propensity to develop glomerulosclerosis in association with a rise in glomerular capillary pressure, we tested whether the renal hemodynamic adaptation to high dietary Na+ intake differs in salt-sensitive and salt-resistant hypertensive patients. We studied 17 black and nine white patients with essential hypertension who were placed on a low Na+ diet (20 meq/day) for 9 days, followed by a high Na+ diet (200 meq/day) for 14 days. During the last 4 days of each diet regimen, they received 30 mg/day of slow-release nifedipine. Eleven blacks were salt-sensitive, and all whites were salt-resistant. During the low Na+ diet period, salt-sensitive and salt-resistant patients had similar mean arterial pressure, glomerular filtration rate, effective renal plasma flow, and filtration fraction.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- V M Campese
- Department of Medicine, University of Southern California Medical Center, Los Angeles 90033
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16
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Oshima T, Young EW, McCarron DA. Abnormal platelet and lymphocyte calcium handling in prehypertensive rats. Hypertension 1991; 18:111-5. [PMID: 1860705 DOI: 10.1161/01.hyp.18.1.111] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have reported that the basal and stimulated cytosolic free calcium concentrations [( Ca2+]i) are elevated in platelets isolated from 12-14-week-old spontaneously hypertensive rats (SHR) as compared with normotensive Wistar-Kyoto (WKY) rats. To determine whether altered cell calcium metabolism precedes the development of overt hypertension, we measured [Ca2+]i under resting and stimulated conditions in blood platelets and thymic lymphocytes isolated from 4-week-old prehypertensive SHR and WKY rats. Blood pressure was similar in both groups (SHR 95 +/- 8 versus WKY rats 92 +/- 7 mm Hg). Basal [Ca2+]i in platelets was higher in SHR than WKY rats (63.4 +/- 3.9 versus 54.8 +/- 3.1 nM, p less than 0.003). Also the [Ca2+]i response to thrombin was greater in SHR than WKY rats in both the presence and absence of extracellular calcium. For lymphocytes, although no difference was detected in basal [Ca2+]i, the concanavalin A-induced peak [Ca2+]i was higher for SHR than WKY rats in both calcium-containing and calcium-free media. These results suggest that agonist-stimulated calcium influx and calcium discharge from intracellular stores are enhanced in both platelets and lymphocytes of 4-week-old SHR. We conclude that abnormalities in calcium metabolism in two different cell types precede the development of overt hypertension in the SHR.
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Affiliation(s)
- T Oshima
- Division of Nephrology and Hypertension, Oregon Health Sciences University, Portland 97201
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17
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Oshima T, Young EW, Bukoski RD, McCarron DA. Abnormal calcium handling by platelets of spontaneously hypertensive rats. Hypertension 1990; 15:606-11. [PMID: 2347623 DOI: 10.1161/01.hyp.15.6.606] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
There is controversy as to whether platelet intracellular free calcium ([Ca2+]i) is increased in spontaneously hypertensive rats (SHR) as compared with Wistar-Kyoto (WKY) rats. Discrepant results may be due to methodological problems including platelet activation during the collection process and leakage of intracellular dye used for [Ca2+]i measurement. To provide further insight into this problem, [Ca2+]i was estimated in fura-2-loaded platelets isolated from eight SHR and seven WKY rats at 12-14 weeks of age by using a two-syringe blood collection method and a correction method for fura-2 leakage. Basal [Ca2+]i was higher in SHR than in WKY rats (61.6 +/- 5.6 vs. 54.0 +/- 3.9 nM, p less than 0.02). However, the difference disappeared when a correction for fura-2 leakage was not used (109.7 +/- 18.4 vs. 94.9 +/- 9.2 nM, p less than 0.1). Thus, differences in [Ca2+]i between SHR and WKY rats may be obscured if dye leakage from platelets is not taken into account. Thrombin (0.1 units/ml) induced a rise in [Ca2+]i that was greater in SHR than WKY rats, both in the presence (491.4 +/- 31.6 vs. 377.5 +/- 21.7 nM, p less than 0.002) and absence (264.9 +/- 33.6 vs. 228.2 +/- 30.1 nM, p less than 0.05) of calcium in the media. These results indicate that thrombin-stimulated calcium influx as well as discharge of calcium from intracellular stores is increased in SHR platelets. Thus, under both basal and stimulated conditions, platelet calcium handling is abnormal in the SHR.
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Affiliation(s)
- T Oshima
- Division of Nephrology and Hypertension, Oregon Health Sciences University, Portland 97201
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18
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Herlitz H, Andersson OK, Jonsson O, Wysocki M, Persson B, Aurell M. Effect of acute vascular fluid volume expansion on erythrocyte sodium transport in essential hypertension. Scand J Clin Lab Invest 1990; 50:123-8. [PMID: 2187238 DOI: 10.3109/00365519009089143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Evidence exists that volume expansion is associated with the appearance of a circulating sodium transport inhibitor. We have evaluated intra-arterial blood pressure (BP), central venous pressure (CVP), plasma renin activity (PRA), intraerythrocyte sodium content, erythrocyte sodium influx and rate constant of sodium efflux in 10 untreated primary hypertensive men (WHO stages I and II). The investigations were done during baseline conditions and after rapid intravenous infusion of 1 litre of saline (0.9% NaCl solution) over 15-20 min. Volume expansion caused an increase in CVP by 6.0 +/- 0.5 cmH2O (p less than 0.01), while BP only exhibited a slight increase. No significant changes in intraerythrocyte sodium content, sodium influx, sodium efflux rate constant or PRA were found after volume expansion compared to baseline. All patients with low normal PRA experienced a decrease in sodium efflux rate constant after volume expansion. We found a positive correlation between baseline PRA and change in sodium efflux rate constant after volume expansion (r = 0.62, p less than 0.05). At baseline the relationship between PRA and intraerythrocyte sodium content nearly reached statistical significance (r = 0.63, p = 0.054). These results may indicate that acute volume expansion influences the release of a circulating factor, modulating sodium transport in low-renin hypertension.
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Affiliation(s)
- H Herlitz
- Department of Nephrology, University of Göteborg, Sahlgrenska Hospital, Sweden
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19
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Abstract
The possible contribution of dietary electrolyte intake as a cause of or contributor to the development of hypertension has been intensively investigated for over 50 years. Evidence from various sources suggests a role for sodium-salt, chloride, calcium, and magnesium. In this article, we will review the evidence supporting a role for each of these electrolytes in human hypertension.
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Affiliation(s)
- T J Moore
- Endocrine-Hypertension Division, Brigham and Women's Hospital, Boston, Massachusetts 02115
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